1.
Mars
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Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is referred to as the Red Planet because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet, Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan, there are ongoing investigations assessing the past habitability potential of Mars, as well as the possibility of extant life. Future astrobiology missions are planned, including the Mars 2020 and ExoMars rovers, liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is about 6⁄1000 that of the Earths, except at the lowest elevations for short periods. The two polar ice caps appear to be largely of water. The volume of ice in the south polar ice cap, if melted. On November 22,2016, NASA reported finding a large amount of ice in the Utopia Planitia region of Mars. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior, Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −2.91, which is surpassed only by Jupiter, Venus, the Moon, optical ground-based telescopes are typically limited to resolving features about 300 kilometers across when Earth and Mars are closest because of Earths atmosphere. Mars is approximately half the diameter of Earth with an area only slightly less than the total area of Earths dry land. Mars is less dense than Earth, having about 15% of Earths volume and 11% of Earths mass, the red-orange appearance of the Martian surface is caused by iron oxide, or rust. It can look like butterscotch, other common colors include golden, brown, tan. Like Earth, Mars has differentiated into a metallic core overlaid by less dense materials. Current models of its interior imply a core with a radius of about 1,794 ±65 kilometers, consisting primarily of iron and this iron sulfide core is thought to be twice as rich in lighter elements than Earths. The core is surrounded by a mantle that formed many of the tectonic and volcanic features on the planet
2.
Rosetta (spacecraft)
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Rosetta was a space probe built by the European Space Agency launched on 2 March 2004. Along with Philae, its lander module, Rosetta performed a study of comet 67P/Churyumov–Gerasimenko. During its journey to the comet, the spacecraft flew by Mars and it was launched as the third cornerstone mission of the ESAs Horizon 2000 programme, after SOHO / Cluster and XMM-Newton. On 6 August 2014, the reached the comet and performed a series of manoeuvres to eventually orbit the comet at distances of 30 to 10 kilometres. On 12 November, its lander module Philae performed the first successful landing on a comet, communications with Philae were briefly restored in June and July 2015, but due to diminishing solar power, Rosettas communications module with the lander was turned off on 27 July 2016. On 30 September 2016, the Rosetta spacecraft ended its mission by hard-landing on the comet in its Maat region, the probe is named after the Rosetta Stone, a stele of Egyptian origin featuring a decree in three scripts. The lander is named after the Philae obelisk, which bears a bilingual Greek and it was one of ESAs Horizon 2000 cornerstone missions. The spacecraft consisted of the Rosetta orbiter, which featured 12 instruments, the Rosetta mission orbited Comet Churyumov–Gerasimenko for 17 months and was designed to complete the most detailed study of a comet ever attempted. The spacecraft was controlled from the European Space Operations Centre, in Darmstadt and it has been estimated that in the decade preceding 2014, some 2,000 people assisted in the mission in some capacity. In 2007, Rosetta made a Mars gravity assist on its way to Comet Churyumov–Gerasimenko, the spacecraft also performed two asteroid flybys. The craft completed its flyby of asteroid 2867 Šteins in September 2008, later, on 20 January 2014, Rosetta was taken out of a 31-month hibernation mode as it approached Comet Churyumov–Gerasimenko. Rosettas Philae lander successfully made the first soft landing on a comet nucleus when it touched down on Comet Churyumov–Gerasimenko on 12 November 2014. On 5 September 2016, ESA announced that the lander was discovered by the narrow-angle camera aboard Rosetta as the made a low,2.7 km pass over the comet. The lander sits on its side wedged into a crevice of the comet. During the 1986 approach of Halleys Comet, international space probes were sent to explore the comet, after the probes returned valuable scientific information, it became obvious that follow-ons were needed that would shed more light on cometary composition and answer new questions. Both ESA and NASA started cooperatively developing new probes, the NASA project was the Comet Rendezvous Asteroid Flyby mission. The ESA project was the follow-on Comet Nucleus Sample Return mission, both missions were to share the Mariner Mark II spacecraft design, thus minimising costs. In 1992, after NASA cancelled CRAF due to budgetary limitations, after the spacecraft launch, Gerhard Schwehm was named mission manager, he retired in March 2014
3.
Climate
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Climate is the statistics of weather, usually over a 30-year interval. Climate differs from weather, in that weather only describes the conditions of these variables in a given region. A regions climate is generated by the system, which has five components, atmosphere, hydrosphere, cryosphere, lithosphere. The climate of a location is affected by its latitude, terrain, climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was the Köppen climate classification, the Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region. Paleoclimatology is the study of ancient climates, Climate models are mathematical models of past, present and future climates. Climate change may occur long and short timescales from a variety of factors. For example, a 3°C change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km in latitude or 500 m in elevation, therefore, species are expected to move upwards in elevation or towards the poles in latitude in response to shifting climate zones. Climate is commonly defined as the weather averaged over a long period, the standard averaging period is 30 years, but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations, the classical period is 30 years, as defined by the World Meteorological Organization. These quantities are most often surface variables such as temperature, precipitation, Climate in a wider sense is the state, including a statistical description, of the climate system. The World Meteorological Organization describes climate normals as reference points used by climatologists to compare current climatological trends to that of the past or what is considered normal, a Normal is defined as the arithmetic average of a climate element over a 30-year period. A30 year period is used, as it is enough to filter out any interannual variation or anomalies. The WMO originated from the International Meteorological Organization which set up a commission for climatology in 1929. At its 1934 Wiesbaden meeting the commission designated the thirty-year period from 1901 to 1930 as the reference time frame for climatological standard normals. In 1982 the WMO agreed to update climate normals, and in these were completed on the basis of climate data from 1 January 1961 to 31 December 1990. The difference between climate and weather is usefully summarized by the popular phrase Climate is what you expect, weather is what you get. Over historical time spans there are a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water and these change only over periods of millions of years due to processes such as plate tectonics
4.
Terrestrial planet
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A terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the planets are the inner planets closest to the Sun, i. e. Mercury, Venus, Earth. The terms terrestrial planet and telluric planet are derived from Latin words for Earth, as these planets are, in terms of composition, Earth-like. All terrestrial planets may have the basic type of structure, such as a central metallic core, mostly iron. The Moon is similar, but has a smaller iron core. Io and Europa are also satellites that have internal structures similar to that of terrestrial planets, terrestrial planets can have canyons, craters, mountains, volcanoes, and other surface structures, depending on the presence of water and tectonic activity. The Solar System has four planets, Mercury, Venus, Earth. Only one terrestrial planet, Earth, is known to have an active hydrosphere, during the formation of the Solar System, there were probably many more terrestrial planetesimals, but most merged with or were ejected by the four terrestrial planets. The Earths Moon has a density of 3.4 g·cm−3 and Jupiters satellites, Io,3.528 and Europa,3.013 g·cm−3, the uncompressed density of a terrestrial planet is the average density its materials would have at zero pressure. A greater uncompressed density indicates greater metal content, uncompressed density differs from the true average density because compression within planet cores increases their density, the average density depends on planet size as well as composition. The uncompressed density of terrestrial planets trends towards lower values as the distance from the Sun increases, the rocky minor planet Vesta orbiting outside of Mars is less dense than Mars still, at 3.4 g·cm−3. It is unknown whether extrasolar terrestrial planets in general will also follow this trend, most of the planets discovered outside the Solar System are giant planets, because they are more easily detectable. But since 2005, hundreds of terrestrial extrasolar planets have been found. Most of these are super-Earths, i. e. planets with masses between Earths and Neptunes, super-Earths may be gas planets or terrestrial, depending on their mass and other parameters. During the early 1990s, the first extrasolar planets were discovered orbiting the pulsar PSR B1257+12, with masses of 0.02,4.3 and it was later found to be a gas giant. In 2005, the first planets around stars that may be terrestrial were found, Gliese 876 d, has a mass 7 to 9 times that of Earth. It orbits the red dwarf Gliese 876,15 light years from Earth, oGLE-2005-BLG-390Lb, about 5.5 times the mass of Earth, orbits a star about 21,000 light years away in the constellation Scorpius. From 2007 to 2010, three potential terrestrial planets were orbiting the red dwarf Gliese 581
5.
Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
6.
Telescope
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A telescope is an optical instrument that aids in the observation of remote objects by collecting electromagnetic radiation. The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s and they found use in both terrestrial applications and astronomy. Within a few decades, the telescope was invented, which used mirrors to collect. In the 20th century many new types of telescopes were invented, including radio telescopes in the 1930s, the word telescope now refers to a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors. The word telescope was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galileis instruments presented at a banquet at the Accademia dei Lincei, in the Starry Messenger, Galileo had used the term perspicillum. The earliest recorded working telescopes were the telescopes that appeared in the Netherlands in 1608. Their development is credited to three individuals, Hans Lippershey and Zacharias Janssen, who were spectacle makers in Middelburg, Galileo heard about the Dutch telescope in June 1609, built his own within a month, and improved upon the design in the following year. Also in 1609, Thomas Harriot became the first person known to point a telescope skyward in order to make observations of a celestial object. The idea that the objective, or light-gathering element, could be a mirror instead of a lens was being investigated soon after the invention of the refracting telescope. The potential advantages of using parabolic mirrors—reduction of spherical aberration and no chromatic aberration—led to many proposed designs, in 1668, Isaac Newton built the first practical reflecting telescope, of a design which now bears his name, the Newtonian reflector. The invention of the lens in 1733 partially corrected color aberrations present in the simple lens and enabled the construction of shorter. The largest reflecting telescopes currently have objectives larger than 10 m, the 20th century also saw the development of telescopes that worked in a wide range of wavelengths from radio to gamma-rays. The first purpose built radio telescope went into operation in 1937, since then, a tremendous variety of complex astronomical instruments have been developed. The name telescope covers a range of instruments. Most detect electromagnetic radiation, but there are differences in how astronomers must go about collecting light in different frequency bands. The near-infrared can be collected much like light, however in the far-infrared and submillimetre range. For example, the James Clerk Maxwell Telescope observes from wavelengths from 3 μm to 2000 μm, on the other hand, the Spitzer Space Telescope, observing from about 3 μm to 180 μm uses a mirror. Also using reflecting optics, the Hubble Space Telescope with Wide Field Camera 3 can observe in the range from about 0.2 μm to 1.7 μm
7.
Mass
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In physics, mass is a property of a physical body. It is the measure of a resistance to acceleration when a net force is applied. It also determines the strength of its gravitational attraction to other bodies. The basic SI unit of mass is the kilogram, Mass is not the same as weight, even though mass is often determined by measuring the objects weight using a spring scale, rather than comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity and this is because weight is a force, while mass is the property that determines the strength of this force. In Newtonian physics, mass can be generalized as the amount of matter in an object, however, at very high speeds, special relativity postulates that energy is an additional source of mass. Thus, any body having mass has an equivalent amount of energy. In addition, matter is a defined term in science. There are several distinct phenomena which can be used to measure mass, active gravitational mass measures the gravitational force exerted by an object. Passive gravitational mass measures the force exerted on an object in a known gravitational field. The mass of an object determines its acceleration in the presence of an applied force, according to Newtons second law of motion, if a body of fixed mass m is subjected to a single force F, its acceleration a is given by F/m. A bodys mass also determines the degree to which it generates or is affected by a gravitational field and this is sometimes referred to as gravitational mass. The standard International System of Units unit of mass is the kilogram, the kilogram is 1000 grams, first defined in 1795 as one cubic decimeter of water at the melting point of ice. Then in 1889, the kilogram was redefined as the mass of the prototype kilogram. As of January 2013, there are proposals for redefining the kilogram yet again. In this context, the mass has units of eV/c2, the electronvolt and its multiples, such as the MeV, are commonly used in particle physics. The atomic mass unit is 1/12 of the mass of a carbon-12 atom, the atomic mass unit is convenient for expressing the masses of atoms and molecules. Outside the SI system, other units of mass include, the slug is an Imperial unit of mass, the pound is a unit of both mass and force, used mainly in the United States
8.
Sun
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The Sun is the star at the center of the Solar System. It is a perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99. 86% of the total mass of the Solar System. About three quarters of the Suns mass consists of hydrogen, the rest is mostly helium, with smaller quantities of heavier elements, including oxygen, carbon, neon. The Sun is a G-type main-sequence star based on its spectral class and it formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into a disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core and it is thought that almost all stars form by this process. The Sun is roughly middle-aged, it has not changed dramatically for more than four billion years and it is calculated that the Sun will become sufficiently large enough to engulf the current orbits of Mercury, Venus, and probably Earth. The enormous effect of the Sun on Earth has been recognized since prehistoric times, the synodic rotation of Earth and its orbit around the Sun are the basis of the solar calendar, which is the predominant calendar in use today. The English proper name Sun developed from Old English sunne and may be related to south, all Germanic terms for the Sun stem from Proto-Germanic *sunnōn. The English weekday name Sunday stems from Old English and is ultimately a result of a Germanic interpretation of Latin dies solis, the Latin name for the Sun, Sol, is not common in general English language use, the adjectival form is the related word solar. The term sol is used by planetary astronomers to refer to the duration of a solar day on another planet. A mean Earth solar day is approximately 24 hours, whereas a mean Martian sol is 24 hours,39 minutes, and 35.244 seconds. From at least the 4th Dynasty of Ancient Egypt, the Sun was worshipped as the god Ra, portrayed as a falcon-headed divinity surmounted by the solar disk, and surrounded by a serpent. In the New Empire period, the Sun became identified with the dung beetle, in the form of the Sun disc Aten, the Sun had a brief resurgence during the Amarna Period when it again became the preeminent, if not only, divinity for the Pharaoh Akhenaton. The Sun is viewed as a goddess in Germanic paganism, Sól/Sunna, in ancient Roman culture, Sunday was the day of the Sun god. It was adopted as the Sabbath day by Christians who did not have a Jewish background, the symbol of light was a pagan device adopted by Christians, and perhaps the most important one that did not come from Jewish traditions
9.
Polar ice cap
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A polar ice cap or polar cap is a high-latitude region of a planet, dwarf planet, or natural satellite that is covered in ice. The composition of the ice will vary, for example, Earths polar caps are mainly water ice, whereas Marss polar ice caps are a mixture of solid carbon dioxide and water ice. Polar ice caps form because high-latitude regions receive less energy in the form of radiation from the Sun than equatorial regions. Earths polar caps have changed dramatically over the last 12,000 years, seasonal variations of the ice caps takes place due to varied solar energy absorption as the planet or moon revolves around the Sun. Additionally, in time scales, the ice caps may grow or shrink due to climate variation. Earths North Pole is covered by floating pack ice over the Arctic Ocean, portions of the ice that do not melt seasonally can get very thick, up to 3–4 meters thick over large areas, with ridges up to 20 meters thick. One-year ice is usually about 1 meter thick, the area covered by sea ice ranges between 9 and 12 million km². In addition, the Greenland ice sheet covers about 1.71 million km², when the ice breaks off it forms icebergs scattered around the northern Atlantic. According to the National Snow and Ice Data Center, since 1979, both 2008 and 2009 had a minimum Arctic sea ice extent somewhat above that of 2007. At other times of the year the ice extent is still sometimes near the 1979–2000 average, as in April 2010, by the data from the National Snow and Ice Data Center. Still, between these years, the overall average ice coverage appears to have declined from 8 million km² to 5 million km². Earths south polar land mass, Antarctica, is covered by the Antarctic ice sheet and it covers an area of about 14.6 million km2 and contains between 25 and 30 million km3 of ice. Around 70% of the water on Earth is contained in this ice sheet. Data from the National Snow and Ice Data Center shows that the sea ice coverage of Antarctica has a positive trend over the last three decades. Over the past several decades, Earth’s polar ice caps have gained significant attention because of the decrease in land. The current rate of decline of the ice caps has caused many investigations and discoveries on glacier dynamics, in the early 1950s, scientists and engineers from the US Army began drilling into polar ice caps for geological insight. Polar ice caps have been used to track current climate patterns but also patterns over the past several years from the traces of CO2. In the past decade, polar ice caps have shown their most rapid decline in size with no sign of recovery
10.
Season
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A season is a division of the year marked by changes in weather, ecology and hours of daylight. Seasons result from the orbit of the Earth around the Sun. During May, June, and July, the northern hemisphere is exposed to direct sunlight because the hemisphere faces the sun. The same is true of the hemisphere in November, December. It is the tilt of the Earth that causes the Sun to be higher in the sky during the months which increases the solar flux. However, due to lag, June, July, and August are the hottest months in the northern hemisphere and December, January. In temperate and subpolar regions, four calendar-based seasons are recognized, spring, summer, autumn or fall. Ecologists often use a model for temperate climate regions, prevernal, vernal, estival, serotinal, autumnal. Many tropical regions have two seasons, the rainy, wet, or monsoon season and the dry season, some have a third cool, mild, or harmattan season. Seasons often held special significance for agrarian societies, whose lives revolved around planting and harvest times, in some parts of the world, some other seasons capture the timing of important ecological events such as hurricane season, tornado season, and wildfire season. The most historically important of these are the three seasons—flood, growth, and low water—which were previously defined by the annual flooding of the Nile in Egypt. The seasons result from the Earths axis of rotation being tilted with respect to its orbital plane by an angle of approximately 23.5 degrees, regardless of the time of year, the northern and southern hemispheres always experience opposite seasons. This is because during summer or winter, one part of the planet is directly exposed to the rays of the Sun than the other. For approximately half of the year, the northern hemisphere tips toward the Sun, for the other half of the year, the same happens, but in the southern hemisphere instead of the northern, with the maximum around December 21. The two instants when the Sun is directly overhead at the Equator are the equinoxes. Also at that moment, both the North Pole and the South Pole of the Earth are just on the terminator, and hence day and night are equally divided between the northern and southern hemispheres. Around the March equinox, the northern hemisphere will be experiencing spring as the hours of daylight increase, the effect of axial tilt is observable as the change in day length and altitude of the Sun at noon during a year. Between this effect and the daylight hours, the axial tilt of the Earth accounts for most of the seasonal variation in climate in both hemispheres
11.
Weather
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Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the lowest level of the atmosphere, Weather refers to day-to-day temperature and precipitation activity, whereas climate is the term for the averaging of atmospheric conditions over longer periods of time. When used without qualification, weather is understood to mean the weather of Earth. Weather is driven by air pressure, temperature and moisture differences between one place and another and these differences can occur due to the suns angle at any particular spot, which varies with latitude. The strong temperature contrast between polar and tropical air gives rise to the largest scale atmospheric circulations, the Hadley Cell, the Ferrel Cell, the Polar Cell, Weather systems in the mid-latitudes, such as extratropical cyclones, are caused by instabilities of the jet stream flow. Because the Earths axis is tilted relative to its orbital plane, on Earths surface, temperatures usually range ±40 °C annually. Over thousands of years, changes in Earths orbit can affect the amount and distribution of energy received by the Earth, thus influencing long-term climate. Surface temperature differences in turn cause pressure differences, higher altitudes are cooler than lower altitudes as most atmospheric heating is due to contact with the Earths surface while radiative losses to space are mostly constant. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. The Earths weather system is a system, as a result. Human attempts to control the weather have occurred throughout history, and there is evidence that human activities such as agriculture, studying how the weather works on other planets has been helpful in understanding how weather works on Earth. A famous landmark in the Solar System, Jupiters Great Red Spot, is a storm known to have existed for at least 300 years. However, weather is not limited to planetary bodies, a stars corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. The movement of mass ejected from the Sun is known as the solar wind, on Earth, the common weather phenomena include wind, cloud, rain, snow, fog and dust storms. Less common events include natural disasters such as tornadoes, hurricanes, typhoons, almost all familiar weather phenomena occur in the troposphere. Weather does occur in the stratosphere and can affect weather lower down in the troposphere, Weather occurs primarily due to air pressure, temperature and moisture differences between one place to another. These differences can occur due to the sun angle at any particular spot, in other words, the farther from the tropics one lies, the lower the sun angle is, which causes those locations to be cooler due the spread of the sunlight over a greater surface. The strong temperature contrast between polar and tropical air gives rise to the large scale atmospheric circulation cells and the jet stream, Weather systems in the mid-latitudes, such as extratropical cyclones, are caused by instabilities of the jet stream flow
12.
Planetary science
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Planetary science or, more rarely, planetology, is the scientific study of planets, moons, and planetary systems and the processes that form them. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation, interrelations, allied disciplines include space physics, when concerned with the effects of the Sun on the bodies of the Solar System, and astrobiology. There are interrelated observational and theoretical branches of planetary science, the theoretical component involves considerable computer simulation and mathematical modelling. There are several major conferences each year, and a range of peer-reviewed journals. But that they are destroyed by colliding with one another, and that some ordered worlds are bare of animals and plants and all water. In more modern times, planetary science began in astronomy, from studies of the unresolved planets, advances in telescope construction and instrumental resolution gradually allowed increased identification of the atmospheric and surface details of the planets. In this scientific process, the instruments were astronomical optical telescopes. The Solar System has now been relatively well-studied, and an overall understanding of the formation and evolution of this planetary system exists. However, there are numbers of unsolved questions, and the rate of new discoveries is very high. This is both an observational and a theoretical science, theoretical planetary astronomy is concerned with dynamics, the application of the principles of celestial mechanics to the Solar System and extrasolar planetary systems. The best known research topics of planetary geology deal with the bodies in the near vicinity of the Earth, the Moon. Of these, the Moon was studied first, using methods developed earlier on the Earth, geomorphology studies the features on planetary surfaces and reconstructs the history of their formation, inferring the physical processes that acted on the surface. For example, the thin dust cover on the surface of the regolith is a result of micrometeorite bombardment. Hydrological features, the involved can range from water to hydrocarbon and ammonia. The history of a surface can be deciphered by mapping features from top to bottom according to their deposition sequence. For example, stratigraphic mapping prepared the Apollo astronauts for the geology they would encounter on their lunar missions. Overlapping sequences were identified on images taken by the Lunar Orbiter program, fortunately, direct samples from the Moon, asteroids and Mars are present on Earth, removed from their parent bodies and delivered as meteorites. The different types of meteorite that originate from the asteroid belt cover almost all parts of the structure of differentiated bodies, meteorites even exist that come from the core-mantle boundary
13.
Climatology
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Climatology or climate science is the study of climate, scientifically defined as weather conditions averaged over a period of time. This modern field of study is regarded as a branch of the sciences and a subfield of physical geography. Climatology now includes aspects of oceanography and biogeochemistry, Climate models are used for a variety of purposes from study of the dynamics of the weather and climate system to projections of future climate. Weather is known as the condition of the atmosphere over a period of time, while Climate has to do with the atmospheric condition over an extended to indefinite period of time. Early climate researchers include Edmund Halley, who published a map of the winds in 1686 after a voyage to the southern hemisphere. Benjamin Franklin first mapped the course of the Gulf Stream for use in sending mail from the United States to Europe, francis Galton invented the term anticyclone. Helmut Landsberg fostered the use of analysis in climatology, which led to its evolution into a physical science. Climatology is approached in various such as Paleoclimatology, which seeks to reconstruct past climates by examining records such as ice cores. Paleotempestology uses these same records to help determine hurricane frequency over millennia, the study of contemporary climates incorporates meteorological data accumulated over many years, such as records of rainfall, temperature and atmospheric composition. Knowledge of the atmosphere and its dynamics is also embodied in models, either statistical or mathematical, modeling is used for understanding past, present and potential future climates. Historical climatology is the study of climate as related to human history, Climate research is made difficult by the large scale, long time periods, and complex processes which govern climate. Climate is governed by laws which can be expressed as differential equations. These equations are coupled and nonlinear, so that solutions are obtained by using numerical methods to create global climate models. Climate is sometimes modeled as a process but this is generally accepted as an approximation to processes that are otherwise too complicated to analyze. Scientists use climate indices based on several climate patterns in their attempt to characterize, Climate indices are generally devised with the twin objectives of simplicity and completeness, and each index typically represents the status and timing of the climate factor it represents. El Niño–Southern Oscillation is a global coupled ocean-atmosphere phenomenon, the Pacific Ocean signatures, El Niño and La Niña are important temperature fluctuations in surface waters of the tropical Eastern Pacific Ocean. La Niña means the little girl and their effect on climate in the subtropics and the tropics are profound. The atmospheric signature, the Southern Oscillation reflects the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin, the most recent occurrence of El Niño started in September 2006 and lasted until early 2007
14.
Ice age
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An ice age is a period of long-term reduction in the temperature of Earths surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Within a long-term ice age, individual pulses of cold climate are termed glacial periods, in the terminology of glaciology, ice age implies the presence of extensive ice sheets in both northern and southern hemispheres. In 1742 Pierre Martel, an engineer and geographer living in Geneva, two years later he published an account of his journey. He reported that the inhabitants of that valley attributed the dispersal of erratic boulders to the glaciers, later similar explanations were reported from other regions of the Alps. In 1815 the carpenter and chamois hunter Jean-Pierre Perraudin explained erratic boulders in the Val de Bagnes in the Swiss canton of Valais as being due to glaciers previously extending further. An unknown woodcutter from Meiringen in the Bernese Oberland advocated a similar idea in a discussion with the Swiss-German geologist Jean de Charpentier in 1834, comparable explanations are also known from the Val de Ferret in the Valais and the Seeland in western Switzerland and in Goethes scientific work. Such explanations could also be found in parts of the world. When the Bavarian naturalist Ernst von Bibra visited the Chilean Andes in 1849–1850, meanwhile, European scholars had begun to wonder what had caused the dispersal of erratic material. From the middle of the 18th century, some discussed ice as a means of transport, the Swedish mining expert Daniel Tilas was, in 1742, the first person to suggest drifting sea ice in order to explain the presence of erratic boulders in the Scandinavian and Baltic regions. In 1795, the Scottish philosopher and gentleman naturalist, James Hutton, two decades later, in 1818, the Swedish botanist Göran Wahlenberg published his theory of a glaciation of the Scandinavian peninsula. He regarded glaciation as a regional phenomenon, only a few years later, the Danish-Norwegian geologist Jens Esmark argued a sequence of worldwide ice ages. In a paper published in 1824, Esmark proposed changes in climate as the cause of those glaciations and he attempted to show that they originated from changes in Earths orbit. During the following years, Esmarks ideas were discussed and taken over in parts by Swedish, Scottish, at the University of Edinburgh Robert Jameson seemed to be relatively open to Esmarks ideas, as reviewed by Norwegian professor of glaciology Bjørn G. Andersen. Jamesons remarks about ancient glaciers in Scotland were most probably prompted by Esmark, in Germany, Albrecht Reinhard Bernhardi, a geologist and professor of forestry at an academy in Dreissigacker, since incorporated in the southern Thuringian city of Meiningen, adopted Esmarks theory. In a paper published in 1832, Bernhardi speculated about former polar ice caps reaching as far as the zones of the globe. When he read his paper before the Schweizerische Naturforschende Gesellschaft, most scientists remained sceptical, finally, Venetz convinced his friend Jean de Charpentier. De Charpentier transformed Venetzs idea into a theory with a limited to the Alps. In fact, both men shared the same volcanistic, or in de Charpentiers case rather plutonistic assumptions, about the Earths history, in 1834, de Charpentier presented his paper before the Schweizerische Naturforschende Gesellschaft
15.
Sublimation (phase transition)
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Sublimation is the phase transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase. Sublimation is a process that occurs at temperatures and pressures below a substances triple point in its phase diagram. The reverse process of sublimation is deposition or desublimation, in which a substance directly from a gas to a solid phase. Sublimation has also used as a generic term to describe a solid-to-gas transition followed by a gas-to-solid transition. At normal pressures, most chemical compounds and elements possess three different states at different temperatures, in these cases, the transition from the solid to the gaseous state requires an intermediate liquid state. The pressure referred to is the pressure of the substance. So, all solids that possess an appreciable vapor pressure at a temperature usually can sublimate in air. The term sublimation refers to a change of state and is not used to describe transformation of a solid to a gas in a chemical reaction. For example, the dissociation on heating of ammonium chloride into hydrogen chloride and ammonia is not sublimation. Similarly the combustion of candles, containing paraffin wax, to carbon dioxide and water vapor is not sublimation, sublimation requires additional energy and is an endothermic change. The enthalpy of sublimation can be calculated by adding the enthalpy of fusion, solid carbon dioxide sublimes everywhere along the line below the triple point, whereas its melting into liquid CO2 can occur only along the line at pressures and temperatures above the triple point. Snow and ice sublime, although more slowly, at temperatures below the freezing/melting point temperature line at 0 °C for most pressures, in freeze-drying, the material to be dehydrated is frozen and its water is allowed to sublime under reduced pressure or vacuum. The loss of snow from a snowfield during a spell is often caused by sunshine acting directly on the upper layers of the snow. Ablation is a process that includes sublimation and erosive wear of glacier ice, naphthalene, an organic compound commonly found in pesticide such as mothball also sublimes. It sublimes easily because it is made of molecules and has van der Waals intermolecular forces. Naphthalene is a solid that sublimes at atmospheric temperature with the sublimation point at around 80˚C or 176˚F. At low temperature, its pressure is high enough,1 mmHg at 53˚C. On the cool surface, the sublimated vapour will be solidified to form a needle-like crystal, iodine produces fumes on gentle heating
16.
Global warming
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Global warming and climate change are terms for the observed century-scale rise in the average temperature of the Earths climate system and its related effects. Multiple lines of evidence show that the climate system is warming. The largest human influence has been emission of gases such as carbon dioxide, methane. These findings have been recognized by the science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing. Future climate change and associated impacts will differ from region to region around the globe, anticipated effects include warming global temperature, rising sea levels, changing precipitation, and expansion of deserts in the subtropics. Warming is expected to be greater over land than over the oceans and greatest in the Arctic, with the retreat of glaciers, permafrost. Effects significant to humans include the threat to security from decreasing crop yields. Possible societal responses to global warming include mitigation by emissions reduction, adaptation to its effects, building systems resilient to its effects, most countries are parties to the United Nations Framework Convention on Climate Change, whose ultimate objective is to prevent dangerous anthropogenic climate change. Public reactions to global warming and concern about its effects are also increasing, a global 2015 Pew Research Center report showed a median of 54% consider it a very serious problem. There are significant regional differences, with Americans and Chinese among the least concerned, the global average surface temperature shows a warming of 0.85 °C in the period 1880 to 2012, based on multiple independently produced datasets. Earths average surface temperature rose by 0. 74±0.18 °C over the period 1906–2005, the rate of warming almost doubled for the last half of that period. The rest has melted ice and warmed the continents and atmosphere, the average temperature of the lower troposphere has increased between 0.12 and 0.135 °C per decade since 1979, according to satellite temperature measurements. The warming that is evident in the temperature record is consistent with a wide range of observations. The probability that these changes could have occurred by chance is virtually zero, temperature changes vary over the globe. Since 1979, land temperatures have increased about twice as fast as ocean temperatures, ocean temperatures increase more slowly than land temperatures because of the larger effective heat capacity of the oceans and because the ocean loses more heat by evaporation. Since the beginning of industrialisation the temperature difference between the hemispheres has increased due to melting of sea ice and snow in the North. Average arctic temperatures have been increasing at almost twice the rate of the rest of the world in the past 100 years, the thermal inertia of the oceans and slow responses of other indirect effects mean that climate can take centuries or longer to adjust to changes in forcing. Some of this warming will be driven by past natural forcings which are still seeking equilibrium in the climate system
17.
Climate of Mars
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It has attracted sustained study from planetologists and climatologists. While Marss climate has similarities to Earths, including seasons and periodic ice ages, there are important differences. Mars atmosphere has a height of approximately 11 km, 60% greater than that on Earth. The climate is of relevance to the question of whether life is or was present on the planet. Mars has been studied by Earth-based instruments since as early as the 17th century, flyby and orbital spacecraft have provided data from above, while direct measurements of atmospheric conditions have been provided by a number of landers and rovers. Advanced Earth orbital instruments today continue to some useful big picture observations of relatively large weather phenomena. The first Martian flyby mission was Mariner 4 which arrived in 1965 and that quick two-day pass was limited and crude in terms of its contribution to the state of knowledge of Martian climate. Later Mariner missions filled in some of the gaps in basic climate information, data-based climate studies started in earnest with the Viking program in 1975 and continues with such probes as the Mars Reconnaissance Orbiter. This observational work has been complemented by a type of computer simulation called the Mars general circulation model. Several different iterations of MGCM have led to an understanding of Mars as well as the limits of such models. Giacomo Maraldi determined in 1704 that the cap is not centered on the rotational pole of Mars. During the opposition of 1719, Maraldi observed both polar caps and temporal variability in their extent, honore Flaugergues 1809 discovery of yellow clouds on the surface of Mars is the first known observation of Martian dust storms. Flaugergues also observed in 1813 significant polar ice waning during Martian springtime and his speculation that this meant that Mars was warmer than earth proved inaccurate. There are two dating systems now in use for Martian geological time, one is based on crater density and has three ages, Noachian, Hesperian, and Amazonian. The other is a timeline, also having three ages, Phyllocian, Theikian, and Siderikian. Recent observations and modeling are producing not only about the present climate and atmospheric conditions on Mars. The Noachian-era Martian atmosphere had long been theorized to be carbon dioxide-rich, Recent spectral observations of deposits of clay minerals on Mars and modeling of clay mineral formation conditions have found that there is little to no carbonate present in clay of that era. Clay formation in a carbon dioxide-rich environment is always accompanied by carbonate formation, the morphology of some crater impacts on Mars indicate that the ground was wet at the time of impact
18.
Exploration of Mars
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The exploration of Mars is the study of Mars by spacecraft. Engineering interplanetary journeys is complicated and the exploration of Mars has experienced a failure rate. Roughly two-thirds of all spacecraft destined for Mars failed before completing their missions, some missions have met with unexpected success, such as the twin Mars Exploration Rovers, which operated for years beyond their specification. No sample return missions have attempted for Mars and an attempted return mission for Mars moon Phobos failed. The search for evidence of habitability, taphonomy, and organic carbon on the planet Mars is now a primary NASA objective, Mars has long been the subject of human interest. Early telescopic observations revealed color changes on the surface that were attributed to seasonal vegetation, further telescopic observations found two moons, Phobos and Deimos, polar ice caps and the feature now known as Olympus Mons, the solar systems tallest mountain. The discoveries piqued further interest in the study and exploration of the red planet. Mars is a planet, like Earth, that formed around the same time, yet with only half the diameter of Earth. The minimum-energy launch windows for a Martian expedition occur at intervals of two years and two months. In addition, the lowest available transfer energy varies on a roughly 16-year cycle, for example, a minimum occurred in the 1969 and 1971 launch windows, rising to a peak in the late 1970s, and hitting another low in 1986 and 1988. Starting in 1960, the Soviets launched a series of probes to Mars including the first intended flybys, the first successful fly-by of Mars was on 14–15 July 1965, by NASAs Mariner 4. On November 14,1971 Mariner 9 became the first space probe to orbit another planet when it entered orbit around Mars. The amount of data returned by probes increased dramatically as technology improved, Mars 6 failed during descent but did return some corrupted atmospheric data in 1974. The 1975 NASA launches of the Viking program consisted of two orbiters, each with a lander that successfully landed in 1976. Viking 1 remained operational for six years, Viking 2 for three, the Viking landers relayed the first color panoramas of Mars. The Soviet probes Phobos 1 and 2 were sent to Mars in 1988 to study Mars, Phobos 1 lost contact on the way to Mars. Phobos 2, while successfully photographing Mars and Phobos, failed before it was set to release two landers to the surface of Phobos, roughly two-thirds of all spacecraft destined for Mars have failed without completing their missions, and it has a reputation as a difficult space exploration target. This mission was a success, having finished its primary mapping mission in early 2001
19.
Mariner 4
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Mariner 4 was the fourth in a series of spacecraft intended for planetary exploration in a flyby mode. It was designed to conduct closeup scientific observations of Mars and to transmit these observations to Earth, launched on November 28,1964, Mariner 4 performed the first successful flyby of the planet Mars, returning the first pictures of the Martian surface. It captured the first images of another planet ever returned from space, their depiction of a cratered. On December 21,1967 communications with Mariner 4 were terminated, the Mariner 4 spacecraft consisted of an octagonal magnesium frame,127 cm across a diagonal and 45.7 cm high. Four solar panels were attached to the top of the frame with a span of 6.88 meters. A116.8 cm diameter parabolic antenna was mounted at the top of the frame as well. An omnidirectional low-gain antenna was mounted on a seven foot, four inch tall mast next to the high-gain antenna, the overall height of the spacecraft was 2.89 meters. The octagonal frame housed the equipment, cabling, midcourse propulsion system. A trapped radiation detector, mounted on the body with counter-axes pointing 70° and 135° from the direction, to measure the intensity. A cosmic ray telescope, mounted inside the body pointing in direction, to measure the direction and energy spectrum of protons. A solar plasma probe, mounted on the body pointing 10° from the solar direction, a cosmic dust detector, mounted on the body with microphone plate approximately perpendicular to the plane of orbit, to measure the momentum, distribution, density, and direction of cosmic dust. A television camera, mounted on a platform at the bottom center of the spacecraft. This subsystem consisted of 4 parts, a Cassegrain telescope with a 1. 05° by 1. 05° field of view, a rechargeable 1200 W·h silver-zinc battery was also used for maneuvers and backup. Monopropellant hydrazine was used for propulsion, via a four-jet vane vector control motor, with 222-newton thrust, the space probes attitude control was provided by 12 cold nitrogen gas jets mounted on the ends of the solar panels and three gyros. Solar pressure vanes, each with an area of 0.65 square meter, were attached to the tips of the solar panels. Positional information was provided by four Sun sensors, and a sensor for either the Earth, Mars, or the star Canopus, during this flight, both the Earth and Mars would be too dim to lock onto. Another bright source at an angle away from the Sun was needed. Subsequently, Canopus was used as a point in many following missions
20.
Mariner 6 and 7
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As part of NASAs wider Mariner program, Mariner 6 and Mariner 7 completed the first dual mission to Mars in 1969. Mariner 6 was launched from Launch Complex 36B at Cape Canaveral Air Force Station, the craft flew over the equator and south polar regions, analyzing the atmosphere and the surface with remote sensors, and recording and relaying hundreds of pictures. Mariner 6 also had the objective of providing experience and data which would be useful in programming the Mariner 7 encounter five days later, three Mariner probes were constructed for the mission, with two intended to fly and one as a spare in the event of a mission failure. The spacecraft were shipped to Cape Canaveral with their Atlas-Centaur boosters in December 1968 – January 1969 to begin pre-launch checkouts, on February 14, Mariner 6 was undergoing a simulated countdown on LC-36A, electrical power running, but no propellant loaded in the booster. During the test run, a relay in the Atlas malfunctioned and opened two valves in the pneumatic system which allowed helium pressure gas to escape from the boosters balloon skin. The Atlas began to crumple over, however two pad technicians quickly activated a manual switch to close the valves and pump helium back in. NASA awarded the quick-thinking technicians, Bill McClure and Jack Beverlin, in 2014, a recently discovered escarpment on Mars was named the McClure-Beverlin Ridge in honor of the pair, who had since passed on. Mariner 6 lifted from LC-36B at Cape Canaveral on February 25,1969, using Atlas-Centaur AC-20 and Mariner 7, from LC-36A on March 27, the boost phase for both spacecraft went according to plan and no serious anomalies occurred with either launch vehicle. A minor LOX leak froze some telemetry probes in AC-20 which registered as a drop in engine fuel pressure, however. AC-20 was launched at a 108-degree azimuth, the Centaur stage on both flights was set up to perform a retrorocket maneuver after capsule separation. On July 29,1969, less than a week before closest approach, the center regained the signal via the backup low-gain antenna and regained use of the high gain antenna again shortly after Mariner 6s close encounter. Leaking gases from a battery were thought to have caused the anomaly, closest approach for Mariner 6 occurred July 31,1969, at 05,19,07 UT at a distance of 3,431 kilometres above the martian surface. Closest approach for Mariner 7 occurred August 5,1969 at 05,00,49 UT at a distance of 3,430 kilometres above the martian surface and this was less than half of the distance used by Mariner 4 on the previous US Mars flyby mission. Both spacecraft are now defunct in heliocentric orbits, by chance, both spacecraft flew over cratered regions and missed both the giant northern volcanoes and the equatorial grand canyon discovered later. In total 201 photos were taken and transmitted back to Earth, adding more detail than the earlier mission, both craft also studied the atmosphere of Mars. Coming a week after Apollo 11, Mariner 6 and 7s flyby of Mars received less than the amount of media coverage for a mission of this significance. The ultraviolet spectrometer onboard Mariners 6 and 7 was constructed by University of Colorados Laboratory for Atmospheric, the engineering model of Mariners 6 and 7 still exists, and is owned by the Jet Propulsion Laboratory. It is on loan to LASP, and is on display in the labs lobby, the Mariner 6 and 7 spacecraft were identical, consisting of an octagonal magnesium frame base,138.4 cm diagonally and 45.7 cm deep
21.
Viking program
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The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two parts, an orbiter designed to photograph the surface of Mars from orbit. The orbiters also served as communication relays for the landers once they touched down, the Viking program grew from NASAs earlier, even more ambitious, Voyager Mars program, which was not related to the successful Voyager deep space probes of the late 1970s. Viking 1 was launched on August 20,1975, and the craft, Viking 2, was launched on September 9,1975. Viking 1 entered Mars orbit on June 19,1976, with Viking 2 following suit on August 7, the Viking 1 lander touched down on the surface of Mars on July 20,1976, and was joined by the Viking 2 lander on September 3. The orbiters continued imaging and performing other operations from orbit while the landers deployed instruments on the surface. The project cost roughly 1 billion USD in 1970s dollars, equivalent to about 11 billion USD in 2016 dollars and it was highly successful and formed most of the body of knowledge about Mars through the late 1990s and early 2000s. Each orbiter, based on the earlier Mariner 9 spacecraft, was an octagon approximately 2.5 m across, the fully fueled orbiter-lander pair had a mass of 3527 kg. After separation and landing, the lander had a mass of about 600 kg, the total launch mass was 2328 kg, of which 1445 kg were propellant and attitude control gas. The eight faces of the structure were 0.4572 m high and were alternately 1.397 and 0.508 m wide. The overall height was 3.29 m from the attachment points on the bottom to the launch vehicle attachment points on top. There were 16 modular compartments,3 on each of the 4 long faces, four solar panel wings extended from the axis of the orbiter, the distance from tip to tip of two oppositely extended solar panels was 9.75 m. The main propulsion unit was mounted above the orbiter bus, propulsion was furnished by a bipropellant liquid-fueled rocket engine which could be gimballed up to 9 degrees. The engine was capable of 1,323 N thrust, translating to a change in velocity of 1480 m/s, attitude control was achieved by 12 small compressed-nitrogen jets. An acquisition Sun sensor, a cruise Sun sensor, a Canopus star tracker, two accelerometers were also on board. Communications were accomplished through a 20 W S-band transmitter and two 20 W TWTAs, an X band downlink was also added specifically for radio science and to conduct communications experiments. A two-axis steerable parabolic dish antenna with a diameter of approximately 1.5 m was attached at one edge of the base. Two tape recorders were each capable of storing 1280 megabits, a 381-MHz relay radio was also available
22.
Mars Reconnaissance Orbiter
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Mars Reconnaissance Orbiter is a multipurpose spacecraft designed to conduct reconnaissance and exploration of Mars from orbit. The US$720 million spacecraft was built by Lockheed Martin under the supervision of the Jet Propulsion Laboratory. The mission is managed by the California Institute of Technology, at the JPL, in La Cañada Flintridge, California, for the NASA Science Mission Directorate, Washington and it was launched August 12,2005, and attained Martian orbit on March 10,2006. In November 2006, after five months of aerobraking, it entered its science orbit. It paves the way for future spacecraft by monitoring Mars daily weather and surface conditions, studying potential landing sites, MROs telecommunications system will transfer more data back to Earth than all previous interplanetary missions combined, and MRO will serve as a highly capable relay satellite for future missions. One of two missions considered for the 2003 Mars launch window, the MRO proposal lost against what became known as the Mars Exploration Rovers. The orbiter mission was rescheduled for launch in 2005, and NASA announced its name, Mars Reconnaissance Orbiter. MRO is modeled after NASAs highly successful Mars Global Surveyor to conduct surveillance of Mars from orbit, early specifications of the satellite included a large camera to take high resolution pictures of Mars. Garvin, the Mars exploration program scientist for NASA, proclaimed that MRO would be a microscope in orbit, the satellite was also to include a visible-near-infrared spectrograph. On October 3,2001, NASA chose Lockheed Martin as the contractor for the spacecrafts fabrication. By the end of 2001 all of the instruments were selected. There were no major setbacks during MROs construction, and the spacecraft was moved to John F. Kennedy Space Center on May 1,2005 to prepare it for launch, MRO science operations were initially scheduled to last two Earth years, from November 2006 to November 2008. One of the main goals is to map the Martian landscape with its high-resolution cameras in order to choose landing sites for future surface missions. The MRO played an important role in choosing the site of the Phoenix Lander. The initial site chosen by scientists was imaged with the HiRISE camera, after analysis with HiRISE and the Mars Odysseys THEMIS instrument a new site was chosen. Mars Science Laboratory, a highly maneuverable rover, also had its landing site inspected, the MRO provided critical navigation data during their landings and acts as a telecommunications relay. MRO is using its onboard scientific equipment to study the Martian climate, weather, atmosphere, and geology, in addition, MRO was tasked with looking for the remains of the previously lost Mars Polar Lander and Beagle 2 spacecraft. Beagle 2 was found by the orbiter at the beginning of 2015, after its main science operations are completed, the probes extended mission is to be the communication and navigation system for landers and rover probes
23.
Mars general circulation model
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Mars climate simulation models date as far back as the Viking missions to Mars. Most Mars climate simulation models were written by researchers that were never reused or open-sourced. By the 1990s the need for a unified model codebase came into being, due to the impact of the internet on climate modelling. This current Mars climate simulation model has its origins with the internet era and this Mars climate model is a complex 3-dimensional model, which represents the processes of atmospheric heating by gases and ground-air heat transfer, as well as large-scale atmospheric motions. The current model has not been modified for use with distributed computing systems like BOINC, the Martian atmosphere contains 10 nmol/mol methane. The first measurements with the Tunable Laser Spectrometer indicated that there is less than 5 ppb of methane at the site at the point of the measurement. The Mars Trace Gas Mission orbiter planned to launch in 2016 would further study the methane, as well as its products such as formaldehyde. On 16 December 2014, NASA reported the Curiosity rover detected a spike, likely localized. Sample measurements taken a dozen times over 20 months showed increases in late 2013 and early 2014, before and after that, readings averaged around one-tenth that level. There are global climate models that have been written for Jupiter, Saturn, Neptune. Atmosphere of Mars Climate of Mars Global climate model Methane
24.
William Herschel
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Frederick William Herschel, KH, FRS was a British astronomer and composer of German origin, and brother of fellow astronomer Caroline Herschel, with whom he worked. Born in the Electorate of Hanover, Herschel followed his father into the Military Band of Hanover, Herschel constructed his first large telescope in 1774, after which he spent nine years carrying out sky surveys to investigate double stars. The resolving power of the Herschel telescopes revealed that the nebulae in the Messier catalogue were clusters of stars, Herschel published catalogues of nebulae in 1802 and in 1820. In the course of an observation on 13 March 1781, he realized that one celestial body he had observed was not a star and this was the first planet to be discovered since antiquity and Herschel became famous overnight. As a result of this discovery, George III appointed him Court Astronomer and he was elected as a Fellow of the Royal Society and grants were provided for the construction of new telescopes. Herschel pioneered the use of astronomical spectrophotometry as a tool, using prisms. Other work included a determination of the rotation period of Mars, the discovery that the Martian polar caps vary seasonally. In addition, Herschel discovered infrared radiation, Herschel was made a Knight of the Royal Guelphic Order in 1816. He was the first President of the Royal Astronomical Society when it was founded in 1820 and he died in August 1822, and his work was continued by his only son, John Herschel. Herschel was born in the Electorate of Hanover in Germany, then part of the Holy Roman Empire and his father was an oboist in the Hanover Military Band. In 1755 the Hanoverian Guards regiment, in whose band Wilhelm, at the time the crowns of Great Britain and Hanover were united under King George II. As the threat of war with France loomed, the Hanoverian Guards were recalled from England to defend Hanover, after they were defeated at the Battle of Hastenbeck, Herschels father Isaak sent his two sons to seek refuge in England in late 1757. Although his older brother Jakob had received his dismissal from the Hanoverian Guards, Wilhelm, nineteen years old at this time, was a quick student of the English language. In England he went by the English rendition of his name, in addition to the oboe, he played the violin and harpsichord and later the organ. He composed numerous works, including 24 symphonies and many concertos. Six of his symphonies were recorded in April 2002 by the London Mozart Players, Herschel moved to Sunderland in 1761 when Charles Avison immediately engaged him as first violin and soloist for his Newcastle orchestra, where he played for one season. In ‘Sunderland in the County of Durh, apprill 20th 1761’ he wrote his Symphony No.8 in C Minor. He was head of the Durham Militia band 1760–61 and visited the home of Sir Ralph Milbanke at Halnaby Hall in 1760, after Newcastle he moved to Leeds and Halifax where he was the first organist at St John the Baptist church
25.
Geological history of Mars
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The geological history of Mars employs observations, indirect and direct measurements, and various inference techniques to estimate the physical evolution of Mars. These include the landers, orbiting platforms, Earth-based observations, observations of the surfaces of many Solar System bodies reveals important clues about their evolution. For example, a flow that spreads out and fills a large impact crater is likely to be younger than the crater. The same methodology was applied to the Moon and then to Mars. Another stratigraphic principle used on planets where impact craters are well preserved is that of number density. The number of greater than a given size per unit surface area provides a relative age for that surface. Heavily cratered surfaces are old, and sparsely cratered surfaces are young, old surfaces have a lot of big craters, and young surfaces have mostly small craters or none at all. These stratigraphic concepts form the basis for the Martian geologic timescale, stratigraphy establishes the relative ages of layers of rock and sediment by denoting differences in composition. Assumptions are often incorporated about the rate of deposition, which generates a range of age estimates across any set of observed sediment layers. The primary technique for calibrating the ages to the Common Era calendar is radiometric dating, combinations of different radioactive materials can improve the uncertainty in an age estimate based on any one isotope. By using stratigraphic principles, rock units ages can usually only be determined relative to each other. For example, knowing that Mesozoic rock strata making up the Cretaceous System lie on top of rocks of the Jurassic System reveals nothing about how long ago the Cretaceous or Jurassic Periods were. Other methods, such as dating, are needed to determine absolute ages in geologic time. Generally, this is known for rocks on the Earth. Absolute ages are known for selected rock units of the Moon based on samples returned to Earth. Assigning absolute ages to rock units on Mars is much more problematic, numerous attempts have been made over the years to determine an absolute Martian chronology by comparing estimated impact cratering rates for Mars to those on the Moon. If the rate of crater formation on Mars by crater size per unit area over geologic time is known with precision. Unfortunately, practical difficulties in crater counting and uncertainties in estimating the flux still create huge uncertainties in the derived from these methods
26.
Noachian
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The Noachian is a geologic system and early time period on the planet Mars characterized by high rates of meteorite and asteroid impacts and the possible presence of abundant surface water. Many of the impact basins on the Moon and Mars formed at this time. The Noachian Period is roughly equivalent to the Earth’s Hadean and early Archean eons when the first life forms likely arose, Noachian-aged terrains on Mars are prime spacecraft landing sites to search for fossil evidence of life. During the Noachian, the atmosphere of Mars was denser than it is today, large lakes and rivers were present in the southern hemisphere, and an ocean may have covered the low-lying northern plains. Extensive volcanism occurred in the Tharsis region, building up enormous masses of volcanic material, weathering of surface rocks produced a diversity of clay minerals that formed under chemical conditions conducive to microbial life. The Noachian System and Period is named after Noachis Terra, a heavily cratered highland region west of the Hellas basin, the type area of the Noachian System is in the Noachis quadrangle around 45°S 340°W. At a large scale, Noachian surfaces are very hilly and rugged, Noachian terrains consist of overlapping and interbedded ejecta blankets of many old craters. Mountainous rim materials and uplifted basement rock from large impact basins are also common, the number-density of large impact craters is very high, with about 400 craters greater than 8 km in diameter per million km2. Martian Time Periods Martian time periods are based on mapping of surface units from spacecraft images. A surface unit is a terrain with a texture, color, albedo, spectral property. Mappers use an approach pioneered in the early 1960s for photogeologic studies of the Moon. Although based on surface characteristics, a unit is not the surface itself or group of landforms. It is a geologic unit representing a sheetlike, wedgelike. A surface unit may be a crater ejecta deposit, lava flow, units of similar age are grouped globally into larger, time-stratigraphic units, called systems. For Mars, three systems are defined, the Noachian, Hesperian, and Amazonian, geologic units lying below the Noachian are informally designated Pre-Noachian. The geologic time equivalent of the Noachian System is the Noachian Period, rock or surface units of the Noachian System were formed or deposited during the Noachian Period. System and Period are not interchangeable terms in formal stratigraphic nomenclature, a system is an idealized stratigraphic column based on the physical rock record of a type area correlated with rocks sections from many different locations planetwide. A system is bound above and below by strata with distinctly different characteristics that indicate dramatic changes in the dominant fauna or environmental conditions, at any location, rock sections in a given system are apt to contain gaps analogous to missing pages from a book
27.
Hesperian
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The Hesperian is a geologic system and time period on the planet Mars characterized by widespread volcanic activity and catastrophic flooding that carved immense outflow channels across the surface. The Hesperian is an intermediate and transitional period of Martian history, during the Hesperian, Mars changed from the wetter and perhaps warmer world of the Noachian to the dry, cold, and dusty planet seen today. The absolute age of the Hesperian Period is uncertain, the beginning of the period followed the end of the late heavy bombardment and probably corresponds to the start of the lunar Late Imbrian period, around 3700 million years ago. The end of the Hesperian Period is much more uncertain and could range anywhere from 3200 to 2000 Mya, the Hesperian Period is roughly coincident with the Earth’s early Archean Eon. With the decline of heavy impacts at the end of the Noachian, volcanism became the primary geologic process on Mars, producing vast plains of flood basalts, by Hesperian times, all of the large shield volcanoes on Mars, including Olympus Mons, had begun to form. Liquid water became more localized in extent and turned more acidic as it interacted with SO2, by the beginning of the Late Hesperian the atmosphere had probably thinned to its present density. As the planet cooled, groundwater stored in the upper crust began to freeze, subsequent volcanic or tectonic activity occasionally fractured the cryosphere, releasing enormous quantities of deep groundwater to the surface and carving huge outflow channels. Much of this flowed into the northern hemisphere where it probably pooled to form large transient lakes or an ice covered ocean. The Hesperian System and Period is named after Hesperia Planum, a moderately cratered highland region northeast of the Hellas basin, the type area of the Hesperian System is in the Mare Tyrrhenum quadrangle around 20°S 245°W. The region consists of rolling, wind-streaked plains with abundant wrinkle ridges resembling those on the lunar maria and these ridged plains are interpreted to be basaltic lava flows that erupted from fissures. The number-density of large craters is moderate, with about 125-200 craters greater than 5 km in diameter per million km2. Martian Time Periods Martian time periods are based on mapping of surface units from spacecraft images. A surface unit is a terrain with a texture, color, albedo, spectral property. Mappers use an approach pioneered in the early 1960s for photogeologic studies of the Moon. Although based on surface characteristics, a unit is not the surface itself or group of landforms. It is a geologic unit representing a sheetlike, wedgelike. A surface unit may be a crater ejecta deposit, lava flow, units of similar age are grouped globally into larger, time-stratigraphic units, called systems. For Mars, three systems are defined, the Noachian, Hesperian, and Amazonian, geologic units lying below the Noachian are informally designated Pre-Noachian
28.
Amazonian (Mars)
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The transition from the preceding Hesperian period is somewhat poorly defined. The Amazonian is thought to have begun around 3 billion years ago, the period is sometimes subdivided into the Early, Middle, and Late Amazonian. The Amazonian continues to the present day, the Amazonian System and Period is named after Amazonis Planitia, which has a sparse crater density over a wide area. Such densities are representative of many Amazonian-aged surfaces, the type area of the Amazonian System is in the Amazonis quadrangle around 15°N 158°W. The scarcity of craters characteristic of the Amazonian also means that unlike the older periods and this enables detailed, process-orientated study of many Amazonian-age surface features of Mars as the necessary details of form of the surface are still visible. Climatic variations have shown to occur in cycles not dissimilar in magnitude. Good preservation has also enabled detailed studies of geological processes on Amazonian Mars, notably volcanic processes, brittle tectonics. System and Period are not interchangeable terms in formal stratigraphic nomenclature, a system is an idealized stratigraphic column based on the physical rock record of a type area correlated with rocks sections from many different locations planetwide. A system is bound above and below by strata with distinctly different characteristics that indicate dramatic changes in the dominant fauna or environmental conditions, at any location, rock sections in a given system are apt to contain gaps analogous to missing pages from a book. In some places, rocks from the system are absent entirely due to nondeposition or later erosion, for example, rocks of the Cretaceous System are absent throughout much of the eastern central interior of the United States. However, the interval of the Cretaceous still occurred there. Thus, a geologic period represents the time interval over which the strata of a system were deposited, periods are measured in years, determined by radioactive dating. On Mars, radiometric ages are not available except from Martian meteorites whose provenance, instead, absolute ages on Mars are determined by impact crater density, which is heavily dependent upon models of crater formation over time. Accordingly, the beginning and end dates for Martian periods are uncertain, especially for the Hesperian/Amazonian boundary, geological history of Mars Geology of Mars Boyce, Joseph, M. The Smithsonian Book of Mars, Konecky & Konecky, Old Saybrook, CT, ISBN 978-1-58834-074-0 Carr, Michael, the Surface of Mars, Cambridge University Press, Cambridge, UK, ISBN 978-0-521-87201-0. A Traveler’s Guide to Mars, The Mysterious Landscapes of the Red Planet, Workman, New York, mapping Mars, Science, Imagination, and the Birth of a World, Picador, New York, ISBN 0-312-42261-X
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Clay minerals
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Clay minerals are hydrous aluminium phyllosilicates, sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay minerals form in the presence of water and have been important to life and they are important constituents of soils, and have been useful to humans since ancient times in agriculture and manufacturing. Clays form flat hexagonal sheets similar to the micas, Clay minerals are common weathering products and low-temperature hydrothermal alteration products. Clay minerals are common in soils, in fine-grained sedimentary rocks such as shale, mudstone. Clay minerals are usually ultrafine-grained and so may require special techniques for their identification. These methods can be augmented by polarized light microscopy, a traditional technique establishing fundamental occurrences or petrologic relationships. Given the requirement of water, clay minerals are rare in the Solar System, though they occur extensively on Earth where water has interacted with other minerals. Clay minerals have been detected at several locations on Mars including Echus Chasma and Mawrth Vallis and the Memnonia quadrangle, spectrography has confirmed their presence on asteroids including the dwarf planet Ceres and Tempel 1 as well as Jupiters moon Europa. A1,1 clay would consist of one sheet and one octahedral sheet. A2,1 clay consists of an octahedral sheet sandwiched between two sheets, and examples are talc, vermiculite and montmorillonite. Smectite group which includes dioctahedral smectites such as montmorillonite, nontronite and beidellite, in 2013, analytical tests by the Curiosity rover found results consistent with the presence of smectite clay minerals on the planet Mars. Illite group which includes the clay-micas, illite is the only common mineral. Chlorite group includes a variety of similar minerals with considerable chemical variation. Other 2,1 clay types exist such as sepiolite or attapulgite, mixed layer clay variations exist for most of the above groups. Ordering is described as random or regular ordering, and is described by the term reichweite. Literature articles will refer to a R1 ordered illite-smectite, for example and this type would be ordered in an ISISIS fashion. R0 on the other hand describes random ordering, and other advanced ordering types are also found, mixed layer clay minerals which are perfect R1 types often get their own names. R1 ordered chlorite-smectite is known as corrensite, R1 illite-smectite is rectorite, knowledge of the nature of clay became better understood in the 1930s with advancements in x-ray diffraction technology necessary to analyze the molecular nature of clay particles
30.
Carbonate
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In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, a polyatomic ion with the formula of CO2−3. The name may mean an ester of carbonic acid, an organic compound containing the carbonate group C2. In geology and mineralogy, the term carbonate can refer both to carbonate minerals and carbonate rock, and both are dominated by the ion, CO2−3. Carbonate minerals are extremely varied and ubiquitous in chemically precipitated sedimentary rock, sodium carbonate and potassium carbonate have been used since antiquity for cleaning and preservation, as well as for the manufacture of glass. Carbonates are widely used in industry, e. g. in iron smelting, as a raw material for Portland cement and lime manufacture, in the composition of ceramic glazes, the carbonate ion is the simplest oxocarbon anion. It consists of one carbon atom surrounded by three oxygen atoms, in a planar arrangement, with D3h molecular symmetry. It has a mass of 60.01 g/mol and carries a total formal charge of −2. It is the base of the hydrogen carbonate ion, HCO−3. The Lewis structure of the ion has two single bonds to negative oxygen atoms, and one short double bond to a neutral oxygen. This structure is incompatible with the symmetry of the ion. This process is called calcination, after calx, the Latin name of quicklime or calcium oxide, CaO, exceptions include lithium, sodium, potassium and ammonium carbonates, as well as many uranium carbonates. In aqueous solution, carbonate, bicarbonate, carbon dioxide, in strongly basic conditions, the carbonate ion predominates, while in weakly basic conditions, the bicarbonate ion is prevalent. In more acid conditions, aqueous carbon dioxide, CO2, is the main form, thus sodium carbonate is basic, sodium bicarbonate is weakly basic, while carbon dioxide itself is a weak acid. Carbonated water is formed by dissolving CO2 in water under pressure, in living systems an enzyme, carbonic anhydrase, speeds the interconversion of CO2 and carbonic acid. Although the carbonate salts of most metals are insoluble in water, in solution this equilibrium between carbonate, bicarbonate, carbon dioxide and carbonic acid changes consonant to changing temperature and pressure conditions. In the case of ions with insoluble carbonates, e. g. CaCO3. This is an explanation for the buildup of scale inside pipes caused by hard water, in organic chemistry a carbonate can also refer to a functional group within a larger molecule that contains a carbon atom bound to three oxygen atoms, one of which is double bonded. These compounds are known as organocarbonates or carbonate esters, and have the general formula ROCOOR′
31.
Clay
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Clay is a fine-grained natural rock or soil material that combines one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to water content and become hard, brittle. Depending on the content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red. Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size, silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in size and other physical properties. The distinction between silt and clay varies by discipline, geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm, sedimentologists often use 4–5 μm, and colloid chemists use 1 μm. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils Atterberg limits, ISO14688 grades clay particles as being smaller than 2 μm and silt particles as being larger. These solvents, usually acidic, migrate through the rock after leaching through upper weathered layers. In addition to the process, some clay minerals are formed through hydrothermal activity. There are two types of deposits, primary and secondary. Primary clays form as residual deposits in soil and remain at the site of formation, secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Clay deposits are associated with very low energy depositional environments such as large lakes. Depending on the source, there are three or four main groups of clays, kaolinite, montmorillonite-smectite, illite, and chlorite. Chlorites are not always considered to be a clay, sometimes being classified as a group within the phyllosilicates. There are approximately 30 different types of clays in these categories. Varve is clay with visible annual layers, which are formed by deposition of those layers and are marked by differences in erosion. This type of deposit is common in glacial lakes
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Hematite
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Hematite, also spelled as haematite, is the mineral form of iron oxide, one of several iron oxides. Hematite crystallizes in the lattice system, and it has the same crystal structure as ilmenite. Hematite and ilmenite form a solid solution at temperatures above 950 °C. Hematite is colored black to steel or silver-gray, brown to reddish brown and it is mined as the main ore of iron. Varieties include kidney ore, martite, iron rose and specularite, while the forms of hematite vary, they all have a rust-red streak. Hematite is harder than iron, but much more brittle. Maghemite is a hematite- and magnetite-related oxide mineral, huge deposits of hematite are found in banded iron formations. Gray hematite is typically found in places that can have still standing water or mineral hot springs, the mineral can precipitate out of water and collect in layers at the bottom of a lake, spring, or other standing water. Hematite can also occur without water, however, usually as the result of volcanic activity, the name hematite is derived from the Greek word for blood αἷμα haima, due to the red coloration found in some varities of hematite. The color of hematite lends itself to use as a pigment, ochre is a clay that is colored by varying amounts of hematite, varying between 20% and 70%. Red ochre contains unhydrated hematite, whereas yellow ochre contains hydrated hematite, the principal use of ochre is for tinting with a permanent color. The red chalk writing of this mineral was one of the earliest in the history of humans, the powdery mineral was first used 164,000 years ago by the Pinnacle-Point man possibly for social purposes. Hematite residues are found in graves from 80,000 years ago. Near Rydno in Poland and Lovas in Hungary red chalk mines have been found that are from 5000 BC, rich deposits of hematite have been found on the island of Elba that have been mined since the time of the Etruscans. Adding to the surprise was a transition with a decrease in temperature at around 260 K to a phase with no net magnetic moment. The disappearance of the moment with a decrease in temperature at 260 K is caused by a change in the anisotropy which causes the moments to align along the c axis, in this configuration, spin canting does not reduce the energy. The magnetic properties of bulk hematite differ from their nanoscale counterparts, for example, the Morin transition temperature of hematite decreases with a decrease in the particle size. Two other end-members are referred to as protohematite and hydrohematite, enhanced magnetic coercivities for hematite have been achieved by dry-heating a 2-line ferrihydrite precursor prepared from solution
33.
Jarosite
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Jarosite is a basic hydrous sulfate of potassium and iron with a chemical formula of KFe3+362. This sulfate mineral is formed in ore deposits by the oxidation of iron sulfides, jarosite is often produced as a byproduct during the purification and refining of zinc and is also commonly associated with acid mine drainage and acid sulfate soil environments. Jarosite has a crystal structure and is brittle, with basal cleavage, a hardness of 2. 5-3.5. It is translucent to opaque with a vitreous to dull luster and it can sometimes be confused with limonite or goethite with which it commonly occurs in the gossan. Jarosite is an analogue of the potassium aluminium sulfate, alunite. The alunite supergroup includes the alunite, jarosite, beudantite, crandallite and florencite subgroups, the alunite supergroup minerals are isostructural with each other and substitution between them occurs, resulting in several solid solution series. The alunite supergroup has the general formula AB326, in the alunite subgroup B is Al, and in the jarosite subgroup B is Fe3+. The beudantite subgroup has the general formula AB36, the crandallite subgroup AB325. H2O, in the jarosite-alunite series Al may substitute for Fe and a complete solid solution series between jarosite and alunite, KAl326, probably exists, but intermediate members are rare. The material from Kopec, Czech Republic, has about equal Fe and Al, in the jarosite-natrojarosite series Na substitutes for K to at least Na/K =1,2.4 but the pure sodium end member NaFe3+326 is not known in nature. Minerals with Na > K are known as natrojarosite and this indicates that there is a wide miscibility gap between the two end members, and it is doubtful whether a complete series exists between jarosite and natrojarosite. Hydroniumjarosite will only form from alkali-deficient solutions, as alkali-rich jarosite forms preferentially, divalent cations may also substitute for the monovalent cation K+ in the A site. Charge balance may be achieved in three ways, firstly by replacing two monovalent cations by one divalent cation, and leaving an A site vacancy, as in plumbogummite, Pb2+Al325. H2O, which is a member of the crandallite subgroup. Secondly by incorporating divalent ions in the B sites, as in osarizawaite, Pb2+Cu2+Al226, alunite subgroup, thirdly by replacing divalent anions with trivalent anions, as in beudantite, PbFe3+33−6, beudantite subgroup. Jarosite was first described in 1852 by August Breithaupt in the Barranco del Jaroso in the Sierra Almagrera, the name jarosite is also directly derived from Jara, the Spanish name of a yellow flower that belongs to the genus Cistus and grows in this sierra. The mineral and the flower have the same color, in 2004 jarosite was detected on Mars by a Mössbauer spectrometer on the MER-B rover, which has been interpreted as strong evidence that Mars once possessed large amounts of liquid water. Jarosite is also a generic term denoting an extensive family of compounds of the form AM362. In condensed matter physics and materials science they are renowned for containing layers with kagome lattice structure, alunite Iron sulfate Spirit Mars rover final embedding event Palache C. Dana’s system of mineralogy, v. II, 560–562, webmineral data Cornell University How an obscure mineral provided a vital clue to Martian water
34.
Opportunity (rover)
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Opportunity, also known as MER-B or MER-1, is a robotic rover active on Mars since 2004. Opportunity has continued to move, gather scientific observations, and report back to Earth for over 50 times its designed lifespan, as of January 17,2017, the rover had traveled 43.79 kilometres. This date was mission time of Sol 4615, mission highlights include the initial 90 sol mission, finding extramartian meteorites such as Heat Shield Rock, and over two years studying Victoria crater. It survived dust-storms and reached Endeavour crater in 2011, which has described as a second landing site. C. The scientific objectives of the Mars Exploration Rover mission are to, Search for and characterize a variety of rocks, in particular, samples sought will include those that have minerals deposited by water-related processes such as precipitation, evaporation, sedimentary cementation or hydrothermal activity. Determine the distribution and composition of minerals, rocks, and soils surrounding the landing sites, determine what geologic processes have shaped the local terrain and influenced the chemistry. Such processes could include water or wind erosion, sedimentation, hydrothermal mechanisms, volcanism, perform calibration and validation of surface observations made by Mars Reconnaissance Orbiter instruments. This will help determine the accuracy and effectiveness of various instruments that survey Martian geology from orbit, Search for iron-containing minerals, identify and quantify relative amounts of specific mineral types that contain water or were formed in water, such as iron-bearing carbonates. Characterize the mineralogy and textures of rocks and soils and determine the processes that created them, Search for geological clues to the environmental conditions that existed when liquid water was present. Assess whether those environments were conducive to life, during the next two decades, NASA will continue to conduct missions to address whether life ever arose on Mars. The search begins with determining whether the Martian environment was ever suitable for life, life, as we understand it, requires water, so the history of water on Mars is critical to finding out if the Martian environment was ever conducive to life. Although the Mars Exploration Rovers do not have the ability to detect life directly, the primary surface mission for Opportunity was planned to last 90 sols. The mission has received several extensions and has been operating for 4821 days since landing, an archive of weekly updates on the rovers status can be found at the Opportunity Update Archive. Its sampling allowed NASA scientists to make hypotheses concerning the presence of hematite, following this, it was directed to travel across the surface of Mars to investigate another crater site, Endurance crater, which it investigated from June – December 2004. Subsequently, Opportunity examined the site of its own heat shield and discovered an intact meteorite, now known as Heat Shield Rock. From late April 2005 to early June of that year, Opportunity was perilously lodged in a sand dune, over a six-week period Earth-based physical simulations were performed to decide how best to extract the rover from its position without risking a permanent immobilization of the valuable vehicle. Successful maneuvering a few centimeters at a time eventually freed the rover and it experienced some mechanical problems with its robotic arm. In late September 2006, Opportunity reached Victoria crater and explored along the rim in a clockwise direction, in June 2007 it returned to Duck Bay, its original arrival point, in September 2007 it entered the crater to begin a detailed study
35.
Goethite
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Goethite, is an iron bearing hydroxide mineral of the diaspore group, is found in soil and other low-temperature environments. Goethite has been known since ancient times for its use as a pigment. Evidence has been found of its use in paint pigment samples taken from the caves of Lascaux in France and it was first described in 1806 based on samples found in the Hollertszug Mine in Herdorf, Germany. The mineral was named after the German polymath and poet Johann Wolfgang von Goethe, in 2003, nanoparticulate authigenic goethite was shown to be the most common diagenetic iron oxyhydroxide in both marine and lake sediments. Goethite is an iron oxyhydroxide containing ferric iron and it is the main component of rust and bog iron ore. Goethites hardness ranges from 5.0 to 5.5 on the Mohs Scale, the mineral forms prismatic needle-like crystals, but is more typically massive. Feroxyhyte and lepidocrocite are both polymorphs of the iron oxyhydroxide FeO, although they have the same chemical formula as goethite, their different crystalline structures make them distinct minerals. Goethite often forms through the weathering of other minerals, and thus is a common component of soils. The formation of goethite is marked by the state change of Fe2+ to Fe3+. Because of this state change, goethite is commonly seen as a pseudomorph. As iron-bearing minerals are brought to the zone of oxidation within the soil and it may also be precipitated by groundwater or in other sedimentary conditions, or form as a primary mineral in hydrothermal deposits. Goethite has also found to be produced by the excretion processes of certain bacteria types. Goethite is found all over the planet, usually in the form of concretions, stalactitic formations, oolites and it is also a very common pseudomorph. It is frequently encountered in the areas at the head of spring waters, on cave floors. The boxworks or gossan resulting from the oxidation of ore deposits is formed of goethite along with other iron oxides. Significant deposits of goethite are found in England, Australia, Cuba, and Michigan, Minnesota, Missouri, Colorado, Alabama, Georgia, Virginia, and Tennessee, and Florida caves in the United States. In 2015 it was reported that limpets teeth have goethite fibres in them and its main modern use is as an iron ore, being referred to as brown iron ore. It does have some use as an earth pigment
36.
Spirit (rover)
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Spirit, also known as MER-A or MER-2, is a robotic rover on Mars, active from 2004 to 2010. It was one of two rovers of NASAs ongoing Mars Exploration Rover Mission and it landed successfully on Mars at 04,35 Ground UTC on January 4,2004, three weeks before its twin, Opportunity, landed on the other side of the planet. Its name was chosen through a NASA-sponsored student essay competition, the rover became stuck in late 2009, and its last communication with Earth was sent on March 22,2010. The rover completed its planned 90-sol mission, aided by cleaning events that resulted in more energy from its solar panels, Spirit went on to function effectively over twenty times longer than NASA planners expected. Spirit also logged 7.73 km of driving instead of the planned 600 m, allowing more extensive analysis of Martian rocks. Initial scientific results from the first phase of the mission were published in an issue of the journal Science. On May 1,2009, Spirit became stuck in soft soil, the rover continued in a stationary science platform role until communication with Spirit stopped on sol 2210. JPL continued to attempt to regain contact until May 24,2011, a formal farewell took place at NASA headquarters after the 2011 Memorial Day holiday and was televised on NASA TV. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASAs Office of Space Science, Washington. The scientific objectives of the Mars Exploration Rover mission were to, Search for and characterize a variety of rocks, in particular, samples sought will include those that have minerals deposited by water-related processes such as precipitation, evaporation, sedimentary cementation or hydrothermal activity. Determine the distribution and composition of minerals, rocks, and soils surrounding the landing sites, determine what geologic processes have shaped the local terrain and influenced the chemistry. Such processes could include water or wind erosion, sedimentation, hydrothermal mechanisms, volcanism, perform calibration and validation of surface observations made by Mars Reconnaissance Orbiter instruments. This will help determine the accuracy and effectiveness of various instruments that survey Martian geology from orbit, Search for iron-containing minerals, identify and quantify relative amounts of specific mineral types that contain water or were formed in water, such as iron-bearing carbonates. Characterize the mineralogy and textures of rocks and soils and determine the processes that created them, Search for geological clues to the environmental conditions that existed when liquid water was present. Assess whether those environments were conducive to life, NASA sought evidence of life on Mars, beginning with the question of whether the Martian environment was ever suitable for life. Life forms known to require water, so the history of water on Mars is a critical piece of knowledge. Although the Mars Exploration Rovers did not have the ability to detect life directly, Spirit are six-wheeled, solar-powered robots standing 1.5 meters high,2.3 meters wide and 1.6 meters long and weighing 180 kilograms. Six wheels on a rocker-bogie system enable mobility over rough terrain, each wheel has its own motor
37.
Valley network
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Valley networks are branching networks of valleys on Mars that superficially resemble terrestrial river drainage basins. They are found mainly incised into the terrain of the southern highlands. The individual valleys are less than 5 kilometers wide, though they may extend for up to hundreds or even thousands of kilometers across the martian surface. Some authors have argued that the properties of the demand that a hydrological cycle must have been active on ancient Mars. The valleys of the networks are typically narrow and 50–200 m deep and their cross-sectional form tends to evolve from V-shaped in the headwaters to U-shaped in the lower reaches. The individual valleys form interconnected branching networks, typically less than 200 km long and draining into local topographic lows, the form of the tributary valleys is commonly described as stubby or a similar term, implying short lengths away from the trunk streams and amphitheater-like terminations at their heads. Any branched valley system on a smaller than an outflow channel can be termed a valley network. Some valley networks run for over 2000 km across the martian landscape, some have drainage densities which do match some terrestrial values. Narrower, less deep valley networks are present, but probably are more rare than their larger equivalents, in most valley networks, later aeolian processes have deposited wind-blown sediments in the bottoms of the valleys, obscuring the nature of the channel which must have cut them. On Earth, a valley is a depression with a floor, across which migrates a channel. Due to the deposits on Mars, however, in almost all cases it is unclear whether the valley floors contain individual channel structures or whether they are fully inundated in flow events. Nanedi Valles is an example where a channel has been identified. This accounts for the preference in the literature for the term valley network rather than channel network, valley networks are very strongly concentrated in the cratered southern uplands of Mars. The Hesperian-age lava plains of the northern hemisphere are in general almost entirely undissected, however, there are significant numbers of exceptions to this generalization - in particular, many of the Hesperian and younger volcanoes carry networks, as well as several other areas. These valleys also appear qualitatively fresher and less degraded than those in the highlands, however, at finer scales than this the distribution of the valleys where present is highly patchy and discontinuous. Within the highlands, it is not unusual to find heavily dissected slopes immediately adjacent to almost entirely unmodified surfaces and they are also much more prominent on steeper slopes, for example on crater rims, but again may only be present on one side of such a rim. However, the channels on Hesperian surfaces unambiguously demonstrate that valley-forming processes did continue at least in some locations at least some of the time after the Noachian, some crater counting evidence even suggests some highland networks may have formed in the Amazonian. Mechanisms and implied environments for the formation of the valleys remain contentious, beyond this, there are several different scenarios that have been advanced to account for the form and distribution in both space and time of the valleys
38.
Martian meteorite
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A Martian meteorite is a rock that formed on the planet Mars and was then ejected from Mars by the impact of an asteroid or comet, and finally landed on the Earth. Of over 61,000 meteorites that have found on Earth,132 were identified as Martian as of 3 March 2014. These meteorites are thought to be from Mars because they have elemental and isotopic compositions that are similar to rocks, the term does not refer to meteorites found on Mars, such as Heat Shield Rock. The meteorite was determined to have formed 2.1 billion years ago during the Amazonian geologic period on Mars, by the early 1980s, it was obvious that the SNC group of meteorites were significantly different from most other meteorite types. Several scientists suggested these characteristics implied the origin of SNC meteorites from a large parent body. Then in 1983, various trapped gases were reported in impact-formed glass of the EET79001 shergottite and these trapped gases provided direct evidence for a Martian origin. In 2000, an article by Treiman, Gleason and Bogard gave a survey of all the used to conclude the SNC meteorites were from Mars. They wrote, There seems little likelihood that the SNCs are not from Mars, if they were from another planetary body, it would have to be substantially identical to Mars as it now is understood. As of January 9,2013,111 of the 114 Martian meteorites are divided into three groups of achondritic meteorites, shergottites, nakhlites, chassignites, and ones otherwise. Consequently, Martian meteorites as a whole are referred to as the SNC group. They have isotope ratios that are said to be consistent with each other, the names derive from the location of where the first meteorite of their type was discovered. Roughly three-quarters of all Martian meteorites can be classified as shergottites and they are named after the Shergotty meteorite, which fell at Sherghati, India in 1865. Shergottites are igneous rocks of mafic to ultramafic lithology and they fall into three main groups, the basaltic, olivine-phyric and lherzolitic shergottites, based on their crystal size and mineral content. They can be categorised alternatively into three or four groups based on their rare-earth element content and these two classification systems do not line up with each other, hinting at complex relationships between the various source rocks and magmas that the shergottites formed from. Because of this, some have advocated the idea that the shergottites are much older than this and this Shergottite Age Paradox remains unsolved and is still an area of active research and debate. The 3-million-year-old crater Mojave,58.5 km in diameter, nakhlites are named after the first of them, the Nakhla meteorite, which fell in El-Nakhla, Alexandria, Egypt in 1911 and had an estimated weight of 10 kg. Nakhlites are igneous rocks that are rich in augite and were formed from basaltic magma about 1.3 billion years ago and they contain augite and olivine crystals. It has been shown that the nakhlites were suffused with liquid water around 620 million years ago and they fell to Earth within the last 10,000 years
39.
Tharsis
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Tharsis is a vast volcanic plateau centered near the equator in the western hemisphere of Mars. The tallest volcano on the planet, Olympus Mons, is associated with the Tharsis region but is actually located off the western edge of the plateau. The name Tharsis is the Greco-Latin transliteration of the biblical Tarshish, Tharsis can have many meanings depending on historical and scientific context. The name is used in a broad sense to represent a continent-sized region of anomalously elevated terrain centered just south of the equator around longitude 265°E. Called the Tharsis bulge or Tharsis rise, this broad, elevated region dominates the western hemisphere of Mars and is the largest topographic feature on the planet, Tharsis has no formally defined boundaries, so precise dimensions for the region are difficult to give. In general, the bulge is about 5,000 km across and it roughly extends from Amazonis Planitia in the west to Chryse Planitia in the east. The bulge is slightly elongated in the direction, running from the northern flanks of Alba Mons to the southern base of the Thaumasia highlands. Depending on how the region is defined, Tharsis covers 10–30 million km2, the greater Tharsis region consists of several geologically distinct subprovinces with different ages and volcano-tectonic histories. The subdivisions given here are informal and may comprise all or parts of other formally named physiographic features, Tharsis is divided into two broad rises, a northern and a larger southern rise. The northern rise partially overlies sparsely cratered, lowland plains north of the dichotomy boundary and this region is dominated by Alba Mons and its extensive volcanic flows. Alba Mons is a vast, low-lying volcanic construct that is unique to Mars, Alba Mons is so large and topographically distinct that it can almost be treated as an entire volcanic province unto itself. The oldest part of the northern rise consists of a broad ridge that corresponds to the highly fractured terrain of Ceraunius Fossae. The ridge is oriented north-south and forms part of the Noachian-aged basement on which Alba Mons sits, the larger southern portion of Tharsis lies on old cratered highland terrain. Its western boundary is defined by the high lava plains of Daedalia Planum. To the east, the southern Tharsis bulge consists of the vast Syria-Thaumasia block, Syria-Thaumasia is bounded to the north by Noctis Labyrinthus and the western three-quarters of Valles Marineris. It is bounded to the east by a north-south oriented ridge called the Coprates rise and these boundaries enclose a broad high plateau and shallow interior basin that include Syria, Sinai, and Solis Plana. The highest plateau elevations on the Tharsis bulge occur in northern Syria Planum, western Noctis Labyrinthus, between the northern and southern portions of the Tharsis bulge lies a relatively narrow, northeast-trending region that may be considered Tharsis proper or central Tharsis. It is defined by the three massive Tharsis Montes volcanoes, a number of volcanic edifices, and adjacent plains consisting of young lava flows
40.
Greenhouse gas
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A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the cause of the greenhouse effect. The primary greenhouse gases in Earths atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, without greenhouse gases, the average temperature of Earths surface would be about −18 °C, rather than the present average of 15 °C. In the Solar System, the atmospheres of Venus, Mars, human activities since the beginning of the Industrial Revolution have produced a 40% increase in the atmospheric concentration of carbon dioxide, from 280 ppm in 1750 to 400 ppm in 2015. This increase has occurred despite the uptake of a portion of the emissions by various natural sinks involved in the carbon cycle. Anthropogenic carbon dioxide emissions come from combustion of fuels, principally coal, oil. Greenhouse gases are those that absorb and emit infrared radiation in the range emitted by Earth. The proportion of an emission remaining in the atmosphere after a time is the airborne fraction. The annual airborne fraction is the ratio of the increase in a given year to that years total emissions. Over the last 50 years the annual airborne fraction for CO2 has been increasing at 0.25 ±0. 21%/year, therefore, they do not contribute significantly to the greenhouse effect and usually are omitted when discussing greenhouse gases. Some gases have indirect radiative effects and this happens in two main ways. One way is that when they break down in the atmosphere they produce another greenhouse gas, for example, methane and carbon monoxide are oxidized to give carbon dioxide. Oxidation of CO to CO2 directly produces an increase in radiative forcing although the reason is subtle. The peak of the thermal IR emission from Earths surface is close to a strong vibrational absorption band of CO2. On the other hand, the single CO vibrational band only absorbs IR at much higher frequencies, where the ~300 K thermal emission of the surface is at least a factor of ten lower. Oxidation of methane to CO2, which requires reactions with the OH radical, produces a reduction, since CO2 is a weaker greenhouse gas than methane. As described below this is not the story, since the oxidations of CO. In any case, the calculation of the radiative effect needs to include both the direct and indirect forcing
41.
Infrared
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It extends from the nominal red edge of the visible spectrum at 700 nanometers, to 1000000 nm. Most of the radiation emitted by objects near room temperature is infrared. Like all EMR, IR carries radiant energy, and behaves both like a wave and like its quantum particle, the photon, slightly more than half of the total energy from the Sun was eventually found to arrive on Earth in the form of infrared. The balance between absorbed and emitted infrared radiation has an effect on Earths climate. Infrared radiation is emitted or absorbed by molecules when they change their rotational-vibrational movements and it excites vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. Infrared spectroscopy examines absorption and transmission of photons in the infrared range, Infrared radiation is used in industrial, scientific, and medical applications. Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected, Infrared thermal-imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect overheating of electrical apparatuses. Thermal-infrared imaging is used extensively for military and civilian purposes, military applications include target acquisition, surveillance, night vision, homing, and tracking. Humans at normal body temperature radiate chiefly at wavelengths around 10 μm, Infrared radiation extends from the nominal red edge of the visible spectrum at 700 nanometers to 1 mm. This range of wavelengths corresponds to a range of approximately 430 THz down to 300 GHz. Below infrared is the portion of the electromagnetic spectrum. Sunlight, at a temperature of 5,780 kelvins, is composed of near thermal-spectrum radiation that is slightly more than half infrared. At zenith, sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level, of this energy,527 watts is infrared radiation,445 watts is visible light, and 32 watts is ultraviolet radiation. Nearly all the radiation in sunlight is near infrared, shorter than 4 micrometers. On the surface of Earth, at far lower temperatures than the surface of the Sun, almost all thermal radiation consists of infrared in mid-infrared region, much longer than in sunlight. Of these natural thermal radiation processes only lightning and natural fires are hot enough to produce much visible energy, thermal infrared radiation also has a maximum emission wavelength, which is inversely proportional to the absolute temperature of object, in accordance with Wiens displacement law. Therefore, the band is often subdivided into smaller sections. Due to the nature of the blackbody radiation curves, typical hot objects, such as exhaust pipes, the three regions are used for observation of different temperature ranges, and hence different environments in space
42.
General circulation model
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A general circulation model is a type of climate model. It employs a model of the general circulation of a planetary atmosphere or ocean. It uses the Navier–Stokes equations on a sphere with thermodynamic terms for various energy sources. These equations are the basis for computer programs used to simulate the Earths atmosphere or oceans, Atmospheric and oceanic GCMs are key components along with sea ice and land-surface components. GCMs and global models are used for weather forecasting, understanding the climate. Versions designed for decade to century time scale climate applications were created by Syukuro Manabe and Kirk Bryan at the Geophysical Fluid Dynamics Laboratory in Princeton. These models are based on the integration of a variety of fluid dynamical, chemical, the acronym GCM originally stood for General Circulation Model. Recently, a second meaning came into use, namely Global Climate Model, while these do not refer to the same thing, General Circulation Models are typically the tools used for modelling climate, and hence the two terms are sometimes used interchangeably. In 1956, Norman Phillips developed a model that could realistically depict monthly. It became the first successful climate model, following Phillipss work, several groups began working to create GCMs. The first to combine both oceanic and atmospheric processes was developed in the late 1960s at the NOAA Geophysical Fluid Dynamics Laboratory, by the early 1980s, the United States National Center for Atmospheric Research had developed the Community Atmosphere Model, this model has been continuously refined. In 1996, efforts began to model soil and vegetation types, later the Hadley Centre for Climate Prediction and Researchs HadCM3 model coupled ocean-atmosphere elements. The role of gravity waves was added in the mid-1980s, gravity waves are required to simulate regional and global scale circulations accurately. Atmospheric and oceanic GCMs can be coupled to form a coupled general circulation model. With the addition of such as a sea ice model or a model for evapotranspiration over land. Thus a carbon CTM may allow a GCM to better predict anthropogenic changes in carbon dioxide concentrations, in addition, this approach allows accounting for inter-system feedback, e. g. chemistry-climate models allow the possible effects of climate change on ozone hole to be studied. Climate prediction uncertainties depend on uncertainties in chemical, physical and social models, significant uncertainties and unknowns remain, especially regarding the future course of human population, industry and technology. Three-dimensional GCMs apply discrete equations for fluid motion and integrate these forward in time and they contain parameterisations for processes such as convection that occur on scales too small to be resolved directly
43.
Viking 1
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Viking 1 was the first of two spacecraft sent to Mars as part of NASAs Viking program. On July 20,1976, it became the first spacecraft to land successfully on Mars, Viking 1 held the record for the longest Mars surface mission of 2307 days or 2245 sols until that record was broken by Opportunity on May 19,2010. Following launch using a Titan/Centaur launch vehicle on August 20,1975, and a 10-month cruise to Mars, the orbiter began returning global images of Mars about 5 days before orbit insertion. The Viking 1 Orbiter was inserted into Mars orbit on June 19,1976, landing on Mars was planned for July 4,1976, the United States Bicentennial, but imaging of the primary landing site showed it was too rough for a safe landing. The landing was delayed until a site was found, and took place instead on July 20. The lander separated from the orbiter at 08,51 UTC and it was the first attempt by the United States at landing on Mars. The instruments of the orbiter consisted of two cameras for imaging, an infrared spectrometer for water vapor mapping and infrared radiometers for thermal mapping. The orbiter primary mission ended at the beginning of solar conjunction on November 5,1976, the extended mission commenced on December 14,1976, after solar conjunction. Operations included close approaches to Phobos in February 1977, the periapsis was reduced to 300 km on March 11,1977. Operations were terminated on August 17,1980, after 1485 orbits, a 2009 analysis concluded that, while the possibility that Viking 1 had impacted mars could not be ruled out, it was most likely still in orbit. The lander and its aeroshell separated from the orbiter on July 20 at 08,51 UTC, at the time of separation, the lander was orbiting at about 5 kilometres per second. The aeroshells retrorockets fired to begin the lander de-orbit maneuver, after a few hours at about 300 kilometres altitude, the lander was reoriented for atmospheric entry. The aeroshell with its heat shield slowed the craft as it plunged through the atmosphere. During this time, entry science experiments were performed by using a retarding potential analyzer, a spectrometer, as well as pressure, temperature. At 6 km altitude, traveling at about 250 metres per second, seven seconds later the aeroshell was jettisoned, and 8 seconds after that the three lander legs were extended. In 45 seconds the parachute had slowed the lander to 60 metres per second, at 1.5 km altitude, retrorockets on the lander itself were ignited and,40 seconds later at about 2.4 m/s, the lander arrived on Mars with a relatively light jolt. The legs had honeycomb aluminum shock absorbers to soften the landing, the landing rockets used an 18-nozzle design to spread the hydrogen and nitrogen exhaust over a large area. NASA calculated that this approach would mean that the surface would not be heated by more than one 1°C, since most of Vikings experiments focused on the surface material a more straightforward design would not have served
44.
Martian year
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Various schemes have been used or proposed for timekeeping on the planet Mars independently of Earth time and calendars. Mars has a tilt and a rotation period similar to those of Earth. Thus it experiences seasons of spring, summer, autumn and winter much like Earth, the average length of a Martian sidereal day is 24h 37m 22. 663s, and the length of its solar day is 24h 39m 35. 244147s. The corresponding values for Earth are 23h 56m 4. 0916s and 24h 00m 00. 002s and this yields a conversion factor of 1.02749125170 days/sol. Thus Mars solar day is only about 2. 7% longer than Earths and this results in the crews schedule sliding approximately 40 minutes later in Earth time each day. Wristwatches calibrated in Martian time, rather than Earth time, were used by many of the MER team members, Local solar time has a significant impact on planning the daily activities of Mars landers. Daylight is needed for the panels of landed spacecraft. Its temperature rises and falls rapidly at sunrise and sunset because Mars does not have the Earths thick atmosphere, alternative clocks for Mars have been proposed, but no mission has chosen to use such. These include a metric time schema, with millidays and centidays, as on Earth, on Mars there is also an equation of time that represents the difference between sundial time and uniform time. The equation of time is illustrated by an analemma, because of orbital eccentricity, the length of the solar day is not quite constant. Mars has a meridian, defined as passing through the small crater Airy-0. However, Mars does not have time zones defined at regular intervals from the prime meridian, each lander so far has used an approximation of local solar time as its frame of reference, as cities did on Earth before the introduction of standard time in the 19th century. Note that the standard for measuring longitude on Mars is planetocentric longitude. The older planetographic longitude was measured from 0°–360° West and used coordinates mapped onto the surface, MTC is a proposed Mars analog to Universal Time on Earth. It is defined as the solar time at Marss prime meridian. The definition of the Martian prime meridian has since been refined on the basis of spacecraft imagery as the center of the crater Airy-0 in Terra Meridiani, MTC is more closely analogous to UT1. Use of the term MTC as the name of a standard time for Mars first appeared in the Mars24 sunclock coded by the NASA Goddard Institute for Space Studies. It replaced Mars24s previous use of the term Airy Mean Time, in an astronomical context, GMT is a deprecated name for Universal Time, or sometimes more specifically for UT1
45.
Mars Orbiter Camera
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The Mars Orbiter Camera and Mars Observer Camera were scientific instruments on board the Mars Observer and Mars Global Surveyor spacecraft. The camera was built by Malin Space Science Systems for NASA, originally named Mars Observer Camera, it was selected by NASA in 1986 for the Mars Observer mission, but it returned only three images of planet Mars before the loss of the spacecraft in 1993. A second camera of the specifications, renamed to Mars Orbiter Camera, was built. The camera returned 243,668 images while in orbit around Mars, Mars Orbiter Camera was operated by its manufacturer, Malin Space Science Systems, from its facilities in San Diego, California. The narrow-angle camera provided 97,097 of the 243,668 images returned by Mars Orbiter Camera, the narrow-angle camera was placed inside an 80 cm-long cylinder with a diameter of 40 cm, and the two wide-angle cameras were attached above the cylinders front area. All cameras were based on CCD technology and were supported by state-of-the-art 1980s electronics, for example, more than 7.6 terabits of data were transferred to and from the Mars Exploration Rovers. The camera also enabled NASA scientists to choose landing sites for other exploration missions
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. Bibcode:2013Icar..222...81F. doi:10.1016/j.icarus.2012.10.019.
