Far side of the Moon
The far side of the Moon is the hemisphere of the Moon that always faces away from Earth. The far side's terrain is rugged with a multitude of impact craters and few flat lunar maria, it has one of the largest craters in the South Pole -- Aitken basin. Both sides of the Moon experience two weeks of sunlight followed by two weeks of night. About 18 percent of the far side is visible from Earth due to libration; the remaining 82 percent remained unobserved until 1959, when it was photographed by the Soviet Luna 3 space probe. The Soviet Academy of Sciences published the first atlas of the far side in 1960; the Apollo 8 astronauts were the first humans to see the far side with the naked eye when they orbited the Moon in 1968. All manned and unmanned soft landings had taken place on the near side of the Moon, until 3 January 2019 when the Chang'e 4 spacecraft made the first landing on the far side. Astronomers have suggested installing a large radio telescope on the far side, where the Moon would shield it from possible radio interference from Earth.
Tidal forces from Earth have slowed down the Moon's rotation to the point where the same side is always facing the Earth—a phenomenon called tidal locking. The other face, most of, never visible from the Earth, is therefore called the "far side of the Moon". Over time, some parts of the far side can be seen due to libration. In total, 59 percent of the Moon's surface is visible from Earth at another. Useful observation of the parts of the far side of the Moon visible from Earth is difficult because of the low viewing angle from Earth; the phrase "dark side of the Moon" does not refer to "dark" as in the absence of light, but rather "dark" as in unknown: until humans were able to send spacecraft around the Moon, this area had never been seen. While many misconstrue this to think that the "dark side" receives little to no sunlight, in reality, both the near and far sides receive equal amounts of light directly from the Sun. However, the near side receives sunlight reflected from the Earth, known as earthshine.
Earthshine does not reach the area of the far side. Only during a full Moon is the whole far side of the Moon dark; the word "dark" has expanded to refer to the fact that communication with spacecraft can be blocked while the spacecraft is on the far side of the Moon, during Apollo space missions for example. The two hemispheres of the Moon have distinctly different appearances, with the near side covered in multiple, large maria; the far side has a battered, densely cratered appearance with few maria. Only 1 % of the surface of the far side is covered compared to 31.2 % on the near side. One accepted explanation for this difference is related to a higher concentration of heat-producing elements on the near-side hemisphere, as has been demonstrated by geochemical maps obtained from the Lunar Prospector gamma-ray spectrometer. While other factors, such as surface elevation and crustal thickness, could affect where basalts erupt, these do not explain why the far side South Pole–Aitken basin was not as volcanically active as Oceanus Procellarum on the near side.
It has been proposed that the differences between the two hemispheres may have been caused by a collision with a smaller companion moon that originated from the Theia collision. In this model, the impact led to an accretionary pile rather than a crater, contributing a hemispheric layer of extent and thickness that may be consistent with the dimensions of the far side highlands; the far side has more visible craters. This was thought to be a result of the effects of lunar lava flows, which cover and obscure craters, rather than a shielding effect from the Earth. NASA calculates that the Earth obscures only about 4 square degrees out of 41,000 square degrees of the sky as seen from the Moon. "This makes the Earth negligible as a shield for the Moon it is that each side of the Moon has received equal numbers of impacts, but the resurfacing by lava results in fewer craters visible on the near side than the far side though both sides have received the same number of impacts."Newer research suggests that heat from Earth at the time when the Moon was formed is the reason the near side has fewer impact craters.
The lunar crust consists of plagioclases formed when aluminium and calcium condensed and combined with silicates in the mantle. The cooler, far side experienced condensation of these elements sooner and so formed a thicker crust; until the late 1950s, little was known about the far side of the Moon. Librations of the Moon periodically allowed limited glimpses of features near the lunar limb on the far side, but only up to 59% of the total surface of the moon; these features, were seen from a low angle, hindering useful observation. The remaining 82% of the surface on the far side remained unknown, its properties were subject to much speculation. An example of a far side feature that can be seen through libration is the Mare Orientale, a prominent impact basin spanning 1,000 km, yet this was not named as a feature until 1906, by Julius Franz in Der Mond; the true natur
An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, related to the term bathymetry, the measurement of depth under water. Altitude can be determined based on the measurement of atmospheric pressure; the greater the altitude, the lower the pressure. When a barometer is supplied with a nonlinear calibration so as to indicate altitude, the instrument is called a pressure altimeter or barometric altimeter. A pressure altimeter is the altimeter found in most aircraft, skydivers use wrist-mounted versions for similar purposes. Hikers and mountain climbers use wrist-mounted or hand-held altimeters, in addition to other navigational tools such as a map, magnetic compass, or GPS receiver; the calibration of an altimeter follows the equation z = c T log , where c is a constant, T is the absolute temperature, P is the pressure at altitude z, Po is the pressure at sea level. The constant c depends on the molar mass of the air.
However, one must be aware that this type of altimeter relies on "density altitude" and its readings can vary by hundreds of feet owing to a sudden change in air pressure, such as from a cold front, without any actual change in altitude. A barometric altimeter, used along with a topographic map, can help to verify one's location, it is more reliable, more accurate, than a GPS receiver for measuring altitude. Because barometric pressure changes with the weather, hikers must periodically re-calibrate their altimeters when they reach a known altitude, such as a trail junction or peak marked on a topographical map. An altimeter is the most important piece of skydiving equipment, after the parachute itself. Altitude awareness is crucial at all times during the jump, determines the appropriate response to maintain safety. Since altitude awareness is so important in skydiving, there is a wide variety of altimeter designs made for use in the sport, a non-student skydiver will use two or more altimeters in a single jump: Hand, wrist or chest-mounted mechanical analogue visual altimeters.
This is the most basic and common type, is used by all student skydivers. The common design has a face marked from 0 to 4000 m, on which an arrow points to the current altitude; the face plate sports sections prominently marked with yellow and red signifying the recommended deployment altitude, as well as emergency procedure decision altitude. A mechanical altimeter has a knob that needs to be manually adjusted to make it point to 0 on the ground before jump, if the landing spot is not at the same altitude as the takeoff spot, the user needs to adjust it appropriately; some advanced electronic altimeters are available which make use of the familiar analogue display, despite internally operating digitally. Digital visual altimeters, mounted on the wrist or hand; this type always operates electronically, conveys the altitude as a number, rather than a pointer on a dial. Since these altimeters contain all the electronic circuitry necessary for altitude calculation, they are equipped with auxiliary functions such as electronic logbook, real-time jump profile replay, speed indication, simulator mode for use in ground training, etc.
An electronic altimeter is activated on the ground before the jump, calibrates automatically to point to 0. It is thus essential that the user not turn it on earlier than necessary to avoid, for example, the drive to a dropzone located at a different altitude than one's home which could cause a fatal false reading. If the intended landing zone is at a different elevation than the takeoff point, the user needs to input the appropriate offset by using a designated function. Audible altimeters; these are inserted into one's helmet, emit a warning tone at a predefined altitude. Contemporary audibles have evolved from their crude beginnings, sport a vast array of functions, such as multiple tones at different altitudes, multiple saved profiles that can be switched electronic logbook with data transfer to a PC for analysis, distinct free fall and canopy modes with different warning altitudes, swoop approach guiding tones, etc. Audibles are auxiliary devices, do not replace, but complement a visual altimeter which remains the primary tool for maintaining altitude awareness.
The advent of modern skydiving disciplines such as freeflying, in which the ground might not be in one's field of view for long periods of time, has made the use of audibles nearly universal, all skydiving helmets come with one or more built-in ports in which an audible might be placed. Audibles are not recommended and banned from use by student skydivers, who need to build up a proper altitude awareness regime for themselves. Auxiliary visual altimeters; these do not show the precise altitude, but rather help maintain a general indicator in one's peripheral vision. They might either operate in tandem with an audible equipped with an appropriate port, in which case they emit warning flashes complementing the audible tones, or be standalone and use another display mode, such as showing either green or red light depending on the altitude. Speaking al
Ranger 5 was a spacecraft of the Ranger program designed to transmit pictures of the lunar surface to Earth stations during a period of 10 minutes of flight prior to impacting on the Moon, to rough-land a seismometer capsule on the Moon, to collect gamma-ray data in flight, to study radar reflectivity of the lunar surface, to continue testing of the Ranger program for development of lunar and interplanetary spacecraft. Due to an unknown malfunction, the spacecraft ceased operation, it passed within 725 km of the Moon. Ranger 5 was a Block II Ranger spacecraft similar to Ranger 3 and Ranger 4; the basic vehicle was 3.1 m high and consisted of a lunar capsule covered with a balsawood impact-limiter, 65 cm in diameter, a mono-propellant mid-course motor, a retrorocket with a thrust of 5080 lbf, a gold and chrome plated hexagonal base 1.5 m in diameter. A large high-gain dish antenna was attached to the base. Two wing-like solar panels were deployed early in the flight. Power was generated by 8680 solar cells contained in the solar panels which charged an 11.5 kg 1 kWh capacity AgZn launching and backup battery.
Spacecraft control was provided by a solid-state digital computer and sequencer and an Earth-controlled command system. Attitude control was provided by six Sun and one Earth sensor and pitch and roll cold nitrogen gas jets; the telemetry system aboard the spacecraft consisted of two 960 MHz transmitters, one at 3 W power output and the other at 50 mW power output, the high-gain antenna, an omnidirectional antenna. White paint and chrome plating, a silvered plastic sheet encasing the retrorocket furnished thermal control; the experimental apparatus included: a vidicon television camera, which employed a scan mechanism that yielded one complete frame in 10 s. The seismometer was encased in the lunar capsule along with an amplifier, a 50 mW transmitter, voltage control, a turnstile antenna, six silver-cadmium batteries capable of operating the lunar capsule transmitter for 30 days, all designed to land on the Moon at 130 to 160 km/h; the instrument package floated in a layer of freon within the balsawood sphere.
The radar altimeter would be used for reflectivity studies, but was designed to initiate capsule separation and ignite the retro-rocket. Ranger 5 was scheduled for launch in June 1962, but NASA instead decided to fly the Mariner Venus probes first which gave more time to work out problems with the spacecraft. After Mariner 1 ended its mission in the Atlantic Ocean instead of interplanetary space, the agency started coming under increased scrutiny from U. S. Congress due to its apparent inability to have any kind of success with planetary probes. Republican Congressman James Fulton confronted NASA Director of the Office of Programs J. J. Wyatt, noting that Mariner 1 had cost U. S. taxpayers $14 million and that there was no excuse at this point to still have failures every launch. As July 1962 ended, there had been 12 planetary probe attempts going back to 1958 and only two accomplished all of their mission goals, it might have been small consolation that Soviet planetary probe efforts during this time were little more successful, however all of their failures were kept secret, in addition the totalitarian Soviet state did not have to answer to the public about the waste of their tax money on failed space missions.
The successful launch of Mariner 2 on August 22 momentarily blunted criticism of NASA and Jet Propulsion Laboratory and seemed to verify the soundness of the Ranger design. Meanwhile, JPL engineers were still trying to figure out what had caused the computer failure on Ranger 4, which had occurred during a period when the probe was out of range of ground tracking; the malfunction was puzzling because the probe had been given thorough ground testing without any anomalies occurring. Examination of telemetry records seemed to suggest that the failure had occurred during separation of Ranger 4 from the Agena, at the point where the electrical interface between the two was disconnected and Ranger 4 would have switched to internal power; the behavior of the probe indicated a transformer or inverter malfunction a short circuit caused by loose metal coatings contacting the pins on the power umbilical attaching the probe to the Agena. Modifications to Ranger 5 included a backup timer to ensure continued operation of the telemetry system if the main computer failed, an additional nitrogen bottle to the attitude control system to reduce gas pressure, an additional pyrotechnic igniter for the midcourse correction engine.
Most extra diodes and fuses were added to the electrical lines to prevent another short from occurring. Ranger 5 was heat-sterilized like Rangers 3-4 had been, so as to prevent unintended contamination of the Moon with Earth microbes. Rolf Halstrup, in charge of the sterilization program, had vocally objected to this procedure as he was convinced that subjecting the probes to a heat dosage was damaging the sensitive electronics in them, he convinced JPL in Pasadena management that sterilization of Ranger 4 had "very likely" damaged the main computer sequencer and timer and that the procedure needed to be stopped to ensure reliability of the spacecraft. Management agreed to stop sterilizing Ranger probes, but only on Ranger 8 and up, as Rangers 6-7 had been sterilized. On August 20, Ranger 5 began the long cross-country trip from state of California to Florida and arrived there the day of Mariner 2's launch. Atlas 215D and Agena 6005 arrived that week
The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite. It is the fifth-largest natural satellite in the Solar System, the largest among planetary satellites relative to the size of the planet that it orbits; the Moon is after Jupiter's satellite Io the second-densest satellite in the Solar System among those whose densities are known. The Moon is thought to have formed not long after Earth; the most accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars-sized body called Theia. The Moon is in synchronous rotation with Earth, thus always shows the same side to Earth, the near side; the near side is marked by dark volcanic maria that fill the spaces between the bright ancient crustal highlands and the prominent impact craters. After the Sun, the Moon is the second-brightest visible celestial object in Earth's sky, its surface is dark, although compared to the night sky it appears bright, with a reflectance just higher than that of worn asphalt.
Its gravitational influence produces the ocean tides, body tides, the slight lengthening of the day. The Moon's average orbital distance is 1.28 light-seconds. This is about thirty times the diameter of Earth; the Moon's apparent size in the sky is the same as that of the Sun, since the star is about 400 times the lunar distance and diameter. Therefore, the Moon covers the Sun nearly during a total solar eclipse; this matching of apparent visual size will not continue in the far future because the Moon's distance from Earth is increasing. The Moon was first reached in September 1959 by an unmanned spacecraft; the United States' NASA Apollo program achieved the only manned lunar missions to date, beginning with the first manned orbital mission by Apollo 8 in 1968, six manned landings between 1969 and 1972, with the first being Apollo 11. These missions returned lunar rocks which have been used to develop a geological understanding of the Moon's origin, internal structure, the Moon's history. Since the Apollo 17 mission in 1972, the Moon has been visited only by unmanned spacecraft.
Both the Moon's natural prominence in the earthly sky and its regular cycle of phases as seen from Earth have provided cultural references and influences for human societies and cultures since time immemorial. Such cultural influences can be found in language, lunar calendar systems and mythology; the usual English proper name for Earth's natural satellite is "the Moon", which in nonscientific texts is not capitalized. The noun moon is derived from Old English mōna, which stems from Proto-Germanic *mēnô, which comes from Proto-Indo-European *mḗh₁n̥s "moon", "month", which comes from the Proto-Indo-European root *meh₁- "to measure", the month being the ancient unit of time measured by the Moon; the name "Luna" is used. In literature science fiction, "Luna" is used to distinguish it from other moons, while in poetry, the name has been used to denote personification of Earth's moon; the modern English adjective pertaining to the Moon is lunar, derived from the Latin word for the Moon, luna. The adjective selenic is so used to refer to the Moon that this meaning is not recorded in most major dictionaries.
It is derived from the Ancient Greek word for the Moon, σελήνη, from, however derived the prefix "seleno-", as in selenography, the study of the physical features of the Moon, as well as the element name selenium. Both the Greek goddess Selene and the Roman goddess Diana were alternatively called Cynthia; the names Luna and Selene are reflected in terminology for lunar orbits in words such as apolune and selenocentric. The name Diana comes from the Proto-Indo-European *diw-yo, "heavenly", which comes from the PIE root *dyeu- "to shine," which in many derivatives means "sky and god" and is the origin of Latin dies, "day"; the Moon formed 4.51 billion years ago, some 60 million years after the origin of the Solar System. Several forming mechanisms have been proposed, including the fission of the Moon from Earth's crust through centrifugal force, the gravitational capture of a pre-formed Moon, the co-formation of Earth and the Moon together in the primordial accretion disk; these hypotheses cannot account for the high angular momentum of the Earth–Moon system.
The prevailing hypothesis is that the Earth–Moon system formed after an impact of a Mars-sized body with the proto-Earth. The impact blasted material into Earth's orbit and the material accreted and formed the Moon; the Moon's far side has a crust, 30 mi thicker than that of the near side. This is thought to be; this hypothesis, although not perfect best explains the evidence. Eighteen months prior to an October 1984 conference on lunar origins, Bill Hartmann, Roger Phillips, Jeff Taylor challenged fellow lunar scientists: "You have eighteen months. Go back to your Apollo data, go back to your computer, do whatever you have to, but make up your mind. Don't come to our conference unless you have something to say about the Moon's birth." At the 1984 conference at Kona, the giant impact hypothesis emerged as the most consensual theory. Before the conference, there were parti
Ranger 1 was a prototype spacecraft launched as part of the Ranger program of unmanned space missions. Its primary mission was to test the performance of those functions and parts necessary for carrying out subsequent lunar and planetary missions. Due to a launch vehicle malfunction, the spacecraft could only reach Low Earth orbit, rather than the high Earth orbit, planned, was only able to complete part of its mission; the spacecraft was of the Ranger Block I design and consisted of a hexagonal base 1.5-meter across upon, mounted a cone-shaped 4-meter-high tower of aluminum struts and braces. Two solar panel wings measuring 5.2 metres from tip to tip extended from the base. A high-gain directional dish antenna was attached to the bottom of the base. Spacecraft experiments and other equipment were mounted on the tower. Instruments aboard the spacecraft included a Lyman-alpha telescope, a rubidium-vapor magnetometer, electrostatic analyzers, medium-energy range particle detectors, two triple coincidence telescopes, a cosmic-ray integrating ionization chamber, cosmic dust detectors, solar X-ray scintillation counters.
There was no camera or midcourse correction engine on the Block I spacecraft. The communications system included the high-gain antenna and an omnidirectional medium-gain antenna and two transmitters, one at 960.1 MHz with 0.25 watts power output and the other at 960.05 MHz with 3 watts power output. Power was to be furnished by 8680 solar cells on the two panels, a 57-kilogram silver-zinc battery, smaller batteries on some of the experiments. Attitude control was provided by a solid-state timing controller and Earth sensors, pitch and roll jets; the temperature was controlled passively by gold plating, white paint, polished aluminum surfaces. The Ranger 1 spacecraft was designed to go into an Earth parking orbit and move into a 60,000-by-1,100,000-kilometre Earth orbit; the purpose of the mission was as an engineering test to verify the functionality of the Ranger hardware. Delay of the 1st countdown July 26: Trajectory information required by the Range Safety Officer was delayed. July 27: A guidance system malfunction in the Atlas booster.
July 28: Engineers found that the guidance program to be fed into the Cape computer contained an error. 1st countdown. July 29. 83 minutes before launch: Power interruptions occurred, requiring momentary holds to permit all stations to check and recover. 28 minutes before launch: Commercial electrical power failed. Inadequate allowance had been made for changes in cable sag caused by variations in temperature on the new power poles installed at Cape Canaveral Air Force Station. 2nd countdown. July 30. Engineers discovered a leak in Ranger's attitude control gas system. 3rd countdown. July 31. A valve malfunctioned in the liquid-oxygen tank on the Atlas booster. 4th countdown. August 1. Ground controllers turned on a spacecraft command applying high voltage to the scientific experiments for calibration purposes. All stations reported a major spacecraft failure. An electrical malfunction had triggered multiple commands from the central clock timer, Ranger 1 "turned on" as it had been programmed to do in orbit.
The explosive squibs fired, solar panels extended inside the shroud, all the experiments commenced to operate. Project engineers disengaged Ranger 1 from the Agena and hastily returned it to Hangar AE. Meantime, the launch was rescheduled for the next available opportunity. Subsequent tests and investigations determined the activating mechanism to have been a voltage discharge to the spacecraft frame. In the days that followed, they replaced and requalified the damaged parts and modified the circuitry to prevent a recurrence of this kind of failure. During the first half of 1961, Lockheed introduced the new Agena B stage which replaced the early test-model Agena A of 1959-60. Agena B had in-orbit restart capability, its first flight with the launch of Midas 3 on July 24 was successful. Several frustrating delays in Ranger 1's launch occurred, including one episode where the spacecraft's timer inadvertently activated on the pad, causing the solar panels to be deployed inside the payload shroud.
After removing Ranger 1 and repairing it, the launch was carried out at 6:04 AM EST on August 23. All went well up to orbital injection, but the planned Agena restart went awry when the engine shut down after only a few seconds, putting the probe in a 312x105 mile track. Subsequent investigation concluded that an electrical circuit in the Agena had overheated from exposure to the Sun; the unintended orbit made it difficult to operate Ranger 1's systems although ground controllers tried to work around it. The main problem they faced was with the solar panels. In addition, the antennas at NASA's various tracking stations had difficulty locking onto the probe due to its orbital plane. During this time, the computer system fired the attitude control jets in a vain attempt to lock onto the Sun with the effect that only one day after launch, the probe ran out of attitude control gas. At this point, it could not be stabilized and the solar panels lost their lock on the Sun. Ranger 1 thus reverted to battery power and continued transmitting until the batteries ran down on August 27 and all signals from the probe ceased.
It was not a total loss.
A gamma ray or gamma radiation, is a penetrating electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves and so imparts the highest photon energy. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays based on their strong penetration of matter. Gamma rays from radioactive decay are in the energy range from a few keV to ~8 MeV, corresponding to the typical energy levels in nuclei with reasonably long lifetimes; the energy spectrum of gamma rays can be used to identify the decaying radionuclides using gamma spectroscopy. Very-high-energy gamma rays in the 100–1000 TeV range have been observed from sources such as the Cygnus X-3 microquasar. Natural sources of gamma rays originating on Earth are as a result of radioactive decay and secondary radiation from atmospheric interactions with cosmic ray particles.
However there are other rare natural sources, such as terrestrial gamma-ray flashes, that produce gamma rays from electron action upon the nucleus. Notable artificial sources of gamma rays include fission, such as occurs in nuclear reactors, as well as high energy physics experiments, such as neutral pion decay and nuclear fusion. Gamma rays and X-rays are both electromagnetic radiation and they overlap in the electromagnetic spectrum, the terminology varies between scientific disciplines. In some fields of physics, they are distinguished by their origin: Gamma rays are created by nuclear decay, while in the case of X-rays, the origin is outside the nucleus. In astrophysics, gamma rays are conventionally defined as having photon energies above 100 keV and are the subject of gamma ray astronomy, while radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy; this convention stems from the early man-made X-rays, which had energies only up to 100 keV, whereas many gamma rays could go to higher energies.
A large fraction of astronomical gamma rays are screened by Earth's atmosphere. Gamma rays are thus biologically hazardous. Due to their high penetration power, they can damage internal organs. Unlike alpha and beta rays, they pass through the body and thus pose a formidable radiation protection challenge, requiring shielding made from dense materials such as lead or concrete; the first gamma ray source to be discovered was the radioactive decay process called gamma decay. In this type of decay, an excited nucleus emits a gamma ray immediately upon formation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, while studying radiation emitted from radium. Villard knew that his described radiation was more powerful than described types of rays from radium, which included beta rays, first noted as "radioactivity" by Henri Becquerel in 1896, alpha rays, discovered as a less penetrating form of radiation by Rutherford, in 1899. However, Villard did not consider naming them as a different fundamental type.
In 1903, Villard's radiation was recognized as being of a type fundamentally different from named rays by Ernest Rutherford, who named Villard's rays "gamma rays" by analogy with the beta and alpha rays that Rutherford had differentiated in 1899. The "rays" emitted by radioactive elements were named in order of their power to penetrate various materials, using the first three letters of the Greek alphabet: alpha rays as the least penetrating, followed by beta rays, followed by gamma rays as the most penetrating. Rutherford noted that gamma rays were not deflected by a magnetic field, another property making them unlike alpha and beta rays. Gamma rays were first thought to be particles like alpha and beta rays. Rutherford believed that they might be fast beta particles, but their failure to be deflected by a magnetic field indicated that they had no charge. In 1914, gamma rays were observed to be reflected from crystal surfaces, proving that they were electromagnetic radiation. Rutherford and his co-worker Edward Andrade measured the wavelengths of gamma rays from radium, found that they were similar to X-rays, but with shorter wavelengths and higher frequency.
This was recognized as giving them more energy per photon, as soon as the latter term became accepted. A gamma decay was understood to emit a gamma photon. Natural sources of gamma rays on Earth include gamma decay from occurring radioisotopes such as potassium-40, as a secondary radiation from various atmospheric interactions with cosmic ray particles; some rare terrestrial natural sources that produce gamma rays that are not of a nuclear origin, are lightning strikes and terrestrial gamma-ray flashes, which produce high energy emissions from natural high-energy voltages. Gamma rays are produced by a number of astronomical processes in which high-energy electrons are produced; such electrons produce secondary gamma rays by the mechanisms of bremsstrahlung, inverse Compton scattering and synchrotron radiation. A large fraction of such astronomical gamma rays are screened by Earth's atmosphere. Notable artificial sources of gamma rays include fission, such as occurs in nuclear reactors, as well as high energy physics experiments, such as neutral pion decay and nuclear fusion.
A sample of gamma ray-emitting material, used for irradiating or imaging is known as a gamma source. It is called a radioactive sou
Cape Canaveral Air Force Station
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing. CCAFS is headquartered at the nearby Patrick Air Force Base, located on Cape Canaveral in Brevard County, Florida, CCAFS; the station is the primary launch head of America's Eastern Range with three launch pads active. Popularly known as "Cape Kennedy" from 1963 to 1973, as "Cape Canaveral" from 1949 to 1963 and from 1973 to the present, the facility is south-southeast of NASA's Kennedy Space Center on adjacent Merritt Island, with the two linked by bridges and causeways; the Cape Canaveral Air Force Station Skid Strip provides a 10,000-foot runway close to the launch complexes for military airlift aircraft delivering heavy and outsized payloads to the Cape. A number of American space exploration pioneers were launched from CCAFS, including the first U. S. Earth satellite in 1958, first U. S. astronaut, first U. S. astronaut in orbit, first two-man U. S. spacecraft, first U. S. unmanned lunar landing, first three-man U.
S. spacecraft. It was the launch site for all of the first spacecraft to fly past each of the planets in the Solar System, the first spacecraft to orbit Mars and roam its surface, the first American spacecraft to orbit and land on Venus, the first spacecraft to orbit Saturn, to orbit Mercury, the first spacecraft to leave the Solar System. Portions of the base have been designated a National Historic Landmark for their association with the early years of the American space program; the CCAFS area had been used by the United States government to test missiles since 1949, when President Harry S. Truman established the Joint Long Range Proving Ground at Cape Canaveral; the location was among the best in the continental United States for this purpose, as it allowed for launches out over the Atlantic Ocean, is closer to the equator than most other parts of the United States, allowing rockets to get a boost from the Earth's rotation. On June 1, 1948, the United States Navy transferred the former Banana River Naval Air Station to the United States Air Force, with the Air Force renaming the facility the Joint Long Range Proving Ground Base on June 10, 1949.
On October 1, 1949, the Joint Long Range Proving Ground Base was transferred from the Air Materiel Command to the Air Force Division of the Joint Long Range Proving Ground. On May 17, 1950, the base was renamed the Long Range Proving Ground Base, but three months was renamed Patrick Air Force Base, in honor of Army Maj. Gen. Mason Patrick. In 1951, the Air Force established the Air Force Missile Test Center. Early American sub-orbital rocket flights were achieved at Cape Canaveral in 1956; these flights occurred shortly after sub-orbital flights launched from White Sands Missile Range, such as the Viking 12 sounding rocket on February 4, 1955. Following the Soviet Union's successful Sputnik 1, the United States attempted its first launch of an artificial satellite from Cape Canaveral on December 6, 1957. However, the rocket carrying Vanguard TV3 exploded on the launch pad. NASA was founded in 1958, Air Force crews launched missiles for NASA from the Cape, known as Cape Canaveral Missile Annex.
Redstone, Pershing 1, Pershing 1a, Pershing II, Thor, Atlas and Minuteman missiles were all tested from the site, the Thor becoming the basis for the expendable launch vehicle Delta rocket, which launched Telstar 1 in July 1962. The row of Titan and Atlas launch pads along the coast came to be known as Missile Row in the 1960s. NASA's first manned spaceflight program was prepared for launch from Canaveral by U. S. Air Force crews. Mercury's objectives were to place a manned spacecraft in Earth orbit, investigate human performance and ability to function in space, safely recover the astronaut and spacecraft. Suborbital flights were launched by derivatives of the Army's Redstone missile from LC-5. Orbital flights were launched by derivatives of the Air Force's larger Atlas D missile from LC-14; the first American in orbit was John Glenn on February 20, 1962. Three more orbital flights followed through May 1963. Flight control for all Mercury missions was provided at the Mercury Control Center located at Canaveral near LC-14.
On November 29, 1963, following the death of President John F. Kennedy, his successor Lyndon B. Johnson issued Executive Order 11129 renaming both NASA's Merrit Island Launch Operations Center and "the facilities of Station No. 1 of the Atlantic Missile Range" as the "John F. Kennedy Space Center", he had convinced Gov. C. Farris Bryant to change the name of Cape Canaveral to Cape Kennedy; this resulted in some confusion in public perception. NASA Administrator James E. Webb clarified this by issuing a directive stating the Kennedy Space Center name applied only to Merrit Island, while the Air Force issued a general order renaming the Air Force Station launch site Cape Kennedy Air Force Station; this name was used through the Gemini and early Apollo programs. However, the geographical name change proved to be unpopular, owing to the historical longevity of Cape Canaveral. In 1973, both the Air Force Base and the geographical Cape names were reverted to Canaveral after the Florida legislature passed a bill changing the name back, signed into law by Florida governor Reubin Askew.