Luna 3
Luna 3, or E-2A No.1 was a Soviet spacecraft launched in 1959 as part of the Luna programme. It was the first-ever mission to photograph the far side of the Moon and the third Soviet space probe to be sent to the neighborhood of the Moon. Though it returned rather poor pictures by standards, the historic, never-before-seen views of the far side of the Moon caused excitement and interest when they were published around the world, a tentative Atlas of the Far Side of the Moon was created after image processing improved the pictures; these views showed mountainous terrain different from the near side, only two dark, low-lying regions which were named Mare Moscoviense and Mare Desiderii. Mare Desiderii was found to be composed of a smaller mare, Mare Ingenii, several other dark craters; the reason for this difference between the two sides of the Moon is still not understood, but it seems that most of the dark lavas that flowed out to produce the maria formed under the Earth-facing half. Luna 3 was followed by the United States with Ranger 7, Ranger 8, Ranger 9.
The space probe was a wide flange near the top. The probe 120 cm at its maximum diameter at the flange. Most of the cylindric section was 95 cm in diameter; the canister was hermetically pressurized to about 0.22 atmosphere. Several solar cells were mounted on the outside of the cylinder, these provided electric power to the storage batteries inside the space probe. Shutters for thermal control were positioned along the cylinder and opened to expose a radiating surface when the internal temperature exceeded 25 °C; the upper hemisphere of the probe held the covered opening for the cameras. Four antennas protruded from the top of two from its bottom. Other scientific equipment was mounted on the outside, including micrometeoroid and cosmic ray detectors, the Yenisey-2 imaging system; the gas jets for its attitude control system were mounted on the lower end of the spacecraft. Several photoelectric cells helped maintain orientation with respect to the Moon. There were no rocket motors for course corrections.
Its interior held the cameras and the photographic film processing system, radio transmitter, storage batteries, gyroscopic units, circulating fans for temperature control. It was spin-stabilized for most of its flight, but its three-axis attitude control system was activated while taking photos. Luna 3 was radio-controlled from ground stations in the Soviet Union. After launching on a Luna 8K72 rocket over the North Pole, the Blok-E escape stage was shut down by radio control to put Luna 3 on its course to the Moon. Initial radio contact showed that the signal from the space probe was only about one-half as strong as expected, the internal temperature was rising; the spacecraft spin axis was reoriented and some equipment was shut down, resulting in a temperature drop from 40 °C to about 30 °C. At a distance of 60,000 to 70,000 km from the Moon, the orientation system was turned on and the spacecraft rotation was stopped; the lower end of the craft was pointed at the Sun, shining on the far side of the Moon.
The space probe passed within 6,200 km of the Moon near its south pole at the closest lunar approach at 14:16 UT on 6 October 1959, continued on over the far side. On 7 October, the photocell on the upper end of the space probe detected the sunlit far side of the Moon, the photography sequence was started; the first picture was taken at 03:30 UT at a distance of 63,500 km from the Moon, the last picture was taken 40 minutes from a distance of 66,700 km. A total of 29 pictures were taken. After the photography was complete the spacecraft resumed spinning, passed over the north pole of the Moon and returned towards the Earth. Attempts to transmit the pictures to the Soviet Union began on October 8 but the early attempts were unsuccessful due to the low signal strength; as Luna 3 drew closer to the Earth, a total of about 17 viewable but poor quality photographs were transmitted by 18 October. All contact with the probe was lost on 22 October 1959; the space probe was believed to have burned up in the Earth's atmosphere in March or April 1960.
Another possibility was. The gravity assist maneuver was first used in 1959 when Luna 3 photographed the far side of Earth's Moon. After launch from the Baikonur Cosmodrome, Luna 3 passed behind the Moon from south to north and headed back to Earth; the gravity of the Moon changed the spacecraft's orbit. The return orbit was calculated so that the spacecraft passed again over the Northern hemisphere where the Soviet ground stations were located; the maneuver relied on research performed under the direction of Mstislav Keldysh at the Steklov Institute of Mathematics. The purpose of this experiment was to obtain photographs of the lunar surface as the spacecraft flew by the Moon; the imaging system was designated Yenisey-2 and consisted of a dual-lens camera AFA-E1, an automatic film processing unit, a scanner. The lenses on the camera were a 200 mm focal length, f/5.6 aperture objective and a 500 mm, f/9.5 objective. The camera carried 40 frames of temperature- and radiation-resistant 35 mm isochrome film.
The 200 mm objective could image the full disk of the Moon and the 500 mm could take an image of a region on the surface. The camera was fixed in the spacecraft and pointing was achieved by rotating the craft itself. Luna 3 was the first successful three-axis stabilized spacecraft. During most of the mission, the s
Mass concentration (astronomy)
In astronomy and astrophysics, a mass concentration is a region of a planet or moon's crust that contains a large positive gravitational anomaly. In general, the word "mascon" can be used as a noun to refer to an excess distribution of mass on or beneath the surface of an astronomical body, such as is found around Hawaii on Earth. However, this term is most used to describe a geologic structure that has a positive gravitational anomaly associated with a feature that might otherwise have been expected to have a negative anomaly, such as the "mascon basins" on the Moon. Typical examples of mascon basins on the Moon are the Imbrium, Serenitatis and Orientale impact basins, all of which exhibit significant topographic depressions and positive gravitational anomalies. Examples of mascon basins on Mars include the Argyre and Utopia basins. Theoretical considerations imply that a topographic low in isostatic equilibrium would exhibit a slight negative gravitational anomaly. Thus, the positive gravitational anomalies associated with these impact basins indicate that some form of positive density anomaly must exist within the crust or upper mantle, supported by the lithosphere.
One possibility is that these anomalies are due to dense mare basaltic lavas, which might reach up to 6 kilometers in thickness for the Moon. While these lavas contribute to the observed gravitational anomalies, uplift of the crust-mantle interface is required to account for their magnitude. Indeed, some mascon basins on the Moon do not appear to be associated with any signs of volcanic activity. Theoretical considerations in either case indicate; the huge expanse of mare basaltic volcanism associated with Oceanus Procellarum does not possess a positive gravitational anomaly. Because of its mascons, the Moon has only four "frozen orbit" inclination zones where a lunar satellite can stay in a low orbit indefinitely. Lunar subsatellites were released on two of the last three Apollo manned lunar landing missions in 1971 and 1972, it was only in 2001 that the mascons were mapped and the frozen orbits were discovered. Since their identification in 1968, the origin of the mascons beneath the surface of the Moon has been subject to much debate, but is now regarded as being the result of the impact of asteroids during the Late Heavy Bombardment.
Lunar mascons alter the local gravity above and around them sufficiently that low and uncorrected satellite orbits around the Moon are unstable on a timescale of months or years. The small perturbations in the orbits accumulate and distort the orbit enough that the satellite impacts the surface; the Luna-10 orbiter was the first artificial object to orbit the Moon and it returned tracking data indicating that the lunar gravitational field caused larger than expected perturbations due to'roughness' of the lunar gravitational field. The Lunar mascons were discovered by Paul M. Muller and William L. Sjogren of the NASA Jet Propulsion Laboratory in 1968 from a new analytic method applied to the precise navigation data from the unmanned pre-Apollo Lunar Orbiter spacecraft; this discovery observed the consistent 1:1 correlation between large positive gravity anomalies and depressed circular basins on the Moon. This fact places key limits on models attempting to follow the history of the Moon's geological development and explain the current lunar internal structures.
At that time, one of NASA's highest priority "tiger team" projects was to explain why the Lunar Orbiter spacecraft being used to test the accuracy of Project Apollo navigation were experiencing errors in predicted position of ten times the mission specification. This meant that the predicted landing areas were 100 times as large as those being defined for reasons of safety. Lunar orbital effects principally resulting from the strong gravitational perturbations of the mascons were revealed as the cause. William Wollenhaupt and Emil Schiesser of the NASA Manned Spacecraft Center in Houston worked out the "fix", first applied to Apollo 12 and permitted its landing within 163 m of the target, the previously-landed Surveyor 3 spacecraft. In May 2013 a NASA study was published with results from the twin GRAIL probes, that mapped mass concentrations on Earth's Moon. Lunar orbit § Perturbation effects
Magnetometer
A magnetometer or magnetic sensor is an instrument that measures magnetism—either the magnetization of a magnetic material like a ferromagnet, or the direction, strength, or relative change of a magnetic field at a particular location. A compass is a simple type of magnetometer, one that measures the direction of an ambient magnetic field; the first magnetometer capable of measuring the absolute magnetic intensity was invented by Carl Friedrich Gauss in 1833 and notable developments in the 19th century included the Hall effect, still used. Magnetometers are used for measuring the Earth's magnetic field and in geophysical surveys to detect magnetic anomalies of various types, they are used in the military to detect submarines. Some countries, such as the United States and Australia, classify the more sensitive magnetometers as military technology, control their distribution. Magnetometers can be used as metal detectors: they can detect only magnetic metals, but can detect such metals at a much larger depth than conventional metal detectors.
In recent years, magnetometers have been miniaturized to the extent that they can be incorporated in integrated circuits at low cost and are finding increasing use as miniaturized compasses. Magnetic fields are vector quantities characterized by both direction; the strength of a magnetic field is measured in units of tesla in the SI units, in gauss in the cgs system of units. 10,000 gauss are equal to one tesla. Measurements of the Earth's magnetic field are quoted in units of nanotesla called a gamma; the Earth's magnetic field can vary from 20,000 to 80,000 nT depending on location, fluctuations in the Earth's magnetic field are on the order of 100 nT, magnetic field variations due to magnetic anomalies can be in the picotesla range. Gaussmeters and teslameters are magnetometers that measure in units of gauss or tesla, respectively. In some contexts, magnetometer is the term used for an instrument that measures fields of less than 1 millitesla and gaussmeter is used for those measuring greater than 1 mT.
There are two basic types of magnetometer measurement. Vector magnetometers measure the vector components of a magnetic field. Total field magnetometers or scalar magnetometers measure the magnitude of the vector magnetic field. Magnetometers used to study the Earth's magnetic field may express the vector components of the field in terms of declination and the inclination. Absolute magnetometers measure the absolute magnitude or vector magnetic field, using an internal calibration or known physical constants of the magnetic sensor. Relative magnetometers measure magnitude or vector magnetic field relative to a fixed but uncalibrated baseline. Called variometers, relative magnetometers are used to measure variations in magnetic field. Magnetometers may be classified by their situation or intended use. Stationary magnetometers are installed to a fixed position and measurements are taken while the magnetometer is stationary. Portable or mobile magnetometers are meant to be used while in motion and may be manually carried or transported in a moving vehicle.
Laboratory magnetometers are used to measure the magnetic field of materials placed within them and are stationary. Survey magnetometers are used to measure magnetic fields in geomagnetic surveys; the performance and capabilities of magnetometers are described through their technical specifications. Major specifications include; the inverse is the cycle time in seconds per reading. Sample rate is important in mobile magnetometers. Bandwidth or bandpass characterizes. For magnetometers with no onboard signal processing, bandwidth is determined by the Nyquist limit set by sample rate. Modern magnetometers may perform averaging over sequential samples. Achieving a lower noise in exchange for lower bandwidth. Resolution is the smallest change in a magnetic field. A magnetometer should have a resolution a good deal smaller than the smallest change one wishes to observe. Quantization error is caused by recording roundoff and truncation of digital expressions of the data. Absolute error is the difference between the readings of a magnetometer true magnetic field.
Drift is the change in absolute error over time. Thermal stability is the dependence of the measurement on temperature, it is given as a temperature coefficient in units of nT per degree Celsius. Noise is the random fluctuations generated by electronics. Noise is given in units of n T / H z. Sensitivity is the larger of the resolution. Heading error is the change in the measurement due to a change in orientation of the instrument in a constant magnetic field; the dead zone is the angular region of magnetometer orientation in which the instrument produces poor or no measurements. All optically pumped, proton-free precession, Overhauser magnetometers experience some dead zone effects. Gradient tolerance is the ability of a ma
Orbital eccentricity
The orbital eccentricity of an astronomical object is a parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit, greater than 1 is a hyperbola; the term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is used for the isolated two-body problem, but extensions exist for objects following a Klemperer rosette orbit through the galaxy. In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit; the eccentricity of this Kepler orbit is a non-negative number. The eccentricity may take the following values: circular orbit: e = 0 elliptic orbit: 0 < e < 1 parabolic trajectory: e = 1 hyperbolic trajectory: e > 1 The eccentricity e is given by e = 1 + 2 E L 2 m red α 2 where E is the total orbital energy, L is the angular momentum, mred is the reduced mass, α the coefficient of the inverse-square law central force such as gravity or electrostatics in classical physics: F = α r 2 or in the case of a gravitational force: e = 1 + 2 ε h 2 μ 2 where ε is the specific orbital energy, μ the standard gravitational parameter based on the total mass, h the specific relative angular momentum.
For values of e from 0 to 1 the orbit's shape is an elongated ellipse. The limit case between an ellipse and a hyperbola, when e equals 1, is parabola. Radial trajectories are classified as elliptic, parabolic, or hyperbolic based on the energy of the orbit, not the eccentricity. Radial orbits hence eccentricity equal to one. Keeping the energy constant and reducing the angular momentum, elliptic and hyperbolic orbits each tend to the corresponding type of radial trajectory while e tends to 1. For a repulsive force only the hyperbolic trajectory, including the radial version, is applicable. For elliptical orbits, a simple proof shows that arcsin yields the projection angle of a perfect circle to an ellipse of eccentricity e. For example, to view the eccentricity of the planet Mercury, one must calculate the inverse sine to find the projection angle of 11.86 degrees. Next, tilt any circular object by that angle and the apparent ellipse projected to your eye will be of that same eccentricity; the word "eccentricity" comes from Medieval Latin eccentricus, derived from Greek ἔκκεντρος ekkentros "out of the center", from ἐκ- ek-, "out of" + κέντρον kentron "center".
"Eccentric" first appeared in English in 1551, with the definition "a circle in which the earth, sun. Etc. deviates from its center". By five years in 1556, an adjectival form of the word had developed; the eccentricity of an orbit can be calculated from the orbital state vectors as the magnitude of the eccentricity vector: e = | e | where: e is the eccentricity vector. For elliptical orbits it can be calculated from the periapsis and apoapsis since rp = a and ra = a, where a is the semimajor axis. E = r a − r p r a + r p = 1 − 2 r a r p + 1 where: ra is the radius at apoapsis. Rp is the radius at periapsis; the eccentricity of an elliptical orbit can be used to obtain the ratio of the periapsis to the apoapsis: r p r a = 1 − e 1 + e For Earth, orbital eccentricity ≈ 0.0167, apoapsis= aphelion and periapsis= perihelion relative to sun. For Earth's annual orbit path, ra/rp ratio = longest_radius / shortest_radius ≈ 1.034 relative to center point of path. The eccentricity of the Earth's orbit is about 0.0167.
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Baikonur Cosmodrome Site 31
Site 31/6 at the Baikonur Cosmodrome, in Kazakhstan, is a launch site used by derivatives of the R-7 Semyorka missile. From 2011 onwards, it was supposed to be the launch site for manned Soyuz missions to the International Space Station, when launches switched from the Soyuz-FG carrier rocket to the Soyuz-2, unable to use the launch pad at Site 1/5. However, Site 1/5 has undergone modifications that allow the manned ISS missions to be launched from it. Only few manned missions to the International Space Station are launched from Site 31/6, when Site 1/5 is unavailable, it was first used on 14 January 1961, for an R-7A ICBM test mission. It is used for commercial Soyuz-FG/Fregat missions, Soyuz-2 launches. In the 1970s and early 1980s, several manned missions were launched from the site. Gagarin's Start "Baikonur LC31". Encyclopedia Astronautica. J. K. Golovanov, "Korolev: Facts and myths", Nauka, 1994, ISBN 5-02-000822-2. ISBN 5-217-02942-0. I. Ostashev, Korolyov, 2001.. Korolev. Yangel." - M. I. Kuznetsk, Voronezh: IPF "Voronezh", 1997, ISBN 5-89981-117-X.
Notes of a military engineer" - Rjazhsky A. A. 2004, SC. first, the publishing house of the "Heroes of the Fatherland" ISBN 5-91017-018-X. "Rocket and space feat Baikonur" - Vladimir Порошков, the "Patriot" publishers 2007. ISBN 5-7030-0969-3 "Unknown Baikonur" - edited by B. I. Posysaeva, M.: "globe", 2001. ISBN 5-8155-0051-8
Gamma-ray spectrometer
A gamma-ray spectrometer is an instrument for measuring the distribution of the intensity of gamma radiation versus the energy of each photon. The study and analysis of gamma-ray spectra for scientific and technical use is called gamma spectroscopy, gamma-ray spectrometers are the instruments which observe and collect such data; because the energy of each photon of EM radiation is proportional to its frequency, gamma rays have sufficient energy that they are observed by counting individual photons. Atomic nuclei have an energy-level structure somewhat analogous to the energy levels of atoms, so that they may emit photons of particular energies, much as atoms do, but at energies that are thousands to millions of times higher than those studied in optical spectroscopy; as with atoms, the particular energy levels of nuclei are characteristic of each species, so that the photon energies of the gamma rays emitted, which correspond to the energy differences of the nuclei, can be used to identify particular elements and isotopes.
Distinguishing between gamma-rays of different energy is an important consideration in the analysis of complex spectra, the ability of a GRS to do so is characterized by the instrument's spectral resolution, or the accuracy with which the energy of each photon is measured. Semi-conductor detectors, based on cooled germanium or silicon detecting elements, have been invaluable for such applications; because the energy level spectrum of nuclei dies out above about 10 MeV, gamma-ray instruments looking to still higher energies observe only continuum spectra, so that the moderate spectral resolution of scintillation suffices for such applications. A number of investigations have been performed to observe the gamma-ray spectra of the Sun and other astronomical sources, both galactic and extra-galactic; the Gamma-Ray Imaging Spectrometer, the Hard X-ray/Low-Energy Gamma-ray experiment on HEAO 1, the Burst and Transient Spectrometry Experiment and the OSSI on CGRO, the C1 germanium gamma-ray instrument on HEAO 3, the Ge gamma-ray spectrometer on the ESA INTEGRAL mission are examples of cosmic spectrometers, while the GRS on the SMM and the imaging Ge spectrometer on the RHESSI satellite have been devoted to solar observations.
Gamma-ray spectrometers have been used for the elemental and isotopic analysis of bodies in the Solar System the Moon and Mars. These surfaces are subjected to a continual bombardment of high-energy cosmic rays, which excite nuclei in them to emit characteristic gamma-rays which can be detected from orbit, thus an orbiting instrument can in principle map the surface distribution of the elements for an entire planet. Examples include the mapping of 20 elements observed in the exploration of Mars and the Moon, they are associated with neutron detectors that can look for water and ice in the soil by measuring neutrons. They are able to measure the abundance and distribution of about 20 primary elements of the periodic table, including silicon, iron, potassium, calcium and carbon. Knowing what elements are at or near the surface will give detailed information about how planetary bodies have changed over time. To determine the elemental makeup of the Martian surface, the Mars Odyssey used a gamma-ray spectrometer and two neutron detectors.
GRS instruments supply data on the distribution and abundance of chemical elements, much as the Lunar Prospector mission did on the moon. In this case, the chemical element thorium was mapped, with higher concentrations shown in yellow/orange/red in the left-hand side image shown on the right; some constructions of scintillation counters can be used as gamma-ray spectrometers. The gamma photon energy is discerned from the intensity of the flash of the scintillator, a number of low-energy photons produced by the single high-energy one. Another approach relies on using Germanium detectors - a crystal of hyperpure germanium that produces pulses proportional to the captured photon energy. Handheld and many laboratory gamma spectrometers are therefore the scintillator kind with thallium-doped sodium iodide, thallium-doped caesium iodide, or, more cerium doped lanthanum bromide. Spectrometers for space missions conversely tend to be of the germanium kind; when exposed to cosmic rays, chemical elements in soils and rocks emit uniquely identifiable signatures of energy in the form of gamma rays.
The gamma-ray spectrometer looks at these signatures, or energies, coming from the elements present in the target soil. By measuring gamma rays coming from the target body, it is possible to calculate the abundance of various elements and how they are distributed around the planet's surface. Gamma rays, emitted from the nuclei of atoms, show up as sharp emission lines on the instrument's spectrum output. While the energy represented in these emissions determines which elements are present, the intensity of the spectrum reveals the elements concentrations. Spectrometers are expected to add to the growing understanding of the origin and evolution
