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Encyclopedia > Phobos (moon)
Phobos

Phobos as imaged by Mars Global Surveyor on June 1, 2003.
Discovery
Discovered by: Asaph Hall
Discovery date: August 18, 1877
Orbital characteristics
Epoch J2000
Periapsis: 9235.6 km
Apoapsis: 9518.8 km
Semi-major axis: 9377.2 km [1]
Orbital circumference: 58,915 km
Eccentricity: 0.0151
Orbital period: 0.318 910 23 d
(7 h 39.2 min)
Avg. orbital speed: 2.138 km/s
Inclination: 1.093° (to Mars' equator)
0.046° (to local Laplace plane)
26.04° (to the ecliptic)
Satellite of: Mars
Physical characteristics
Dimensions: 26.8 × 21 × 18.4 km
Mean radius: 11.1 km
(0.0021 Earths)
Oblateness: 0.31-0.12
Surface area: ~6,100 km²
(11.9 µEarths)
Volume: ~5,500 km³
(5.0 nEarths)
Mass: 1.07×1016 kg
(1.8 nEarths)
Mean density: 1.9 g/cm³
Equatorial surface gravity: 0.0084-0.0019 m/s²
(8.4-1.9 mm/s²)
(860-190 µg)
Escape velocity: 0.011 km/s (11 m/s)
Rotation period: synchronous
Rotation velocity at equator: 11.0 km/h (at longest axis' tips)
Axial tilt:
Albedo: 0.07
Temperature: ~233 K

Phobos (IPA: [ˈfoʊ.bɑs] or [ˈfoʊ.bəs]) (systematic designation: Mars I) is the larger and closer of Mars' two moons (the other being Deimos). Its name, which means "fear" in Greek, refers to Phobos, a son of Ares (Mars) in Greek mythology. Phobos is one of the smallest moons in the solar system, and orbits about 6000 km (3728 mi) above the surface of Mars, closer to a major planet than any other moon. Download high resolution version (665x650, 57 KB)A detailed image of Phobos, taken by Mars Global Surveyor on June 1, 2003. ... The Mars Global Surveyor (MGS) was a US spacecraft developed by NASA and the Jet Propulsion Laboratory and launched November 1996. ... June 1 is the 152nd day of the year (153rd in leap years) in the Gregorian calendar. ... 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... Asaph Hall (October 15, 1829 – November 22, 1907) was an American astronomer who is most famous for having discovered the moons of Mars (namely Deimos and Phobos) in 1877. ... August 18 is the 230th day of the year (231st in leap years) in the Gregorian calendar. ... 1877 (MDCCCLXXVII) was a common year starting on Monday (see link for calendar). ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... The J2000. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... km redirects here. ... The circumference is the distance around a closed curve. ... (This page refers to eccitricity in astrodynamics. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... Look up day in Wiktionary, the free dictionary. ... The hour (symbol: h) is a unit of time. ... A minute is a unit of time equal to 1/60th of an hour and to 60 seconds. ... The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body. ... Look up second in Wiktionary, the free dictionary. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... A degree (in full, a degree of arc, arc degree, or arcdegree), usually symbolized °, is a measurement of plane angle, representing 1/360 of a full rotation. ... The Laplace plane is defined as the mean plane occupied by the orbit of a satellite during a precession cycle. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Adjectives: Martian Atmosphere Surface pressure: 0. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... An oblate spheroid is ellipsoid having a shorter axis and two equal longer axes. ... In mathematics, a spheroid is a quadric surface in three dimensions obtained by rotating an ellipse about one of its principal axes. ... Square kilometre (US spelling: Square kilometer), symbol km², is an SI unit of surface area. ... Look up micro- in Wiktionary, the free dictionary. ... The volume of a solid object is the three-dimensional concept of how much space it occupies, often quantified numerically. ... A cubic kilometre (symbol km³) is an SI derived unit of volume. ... For other uses, see Nano (disambiguation). ... Unsolved problems in physics: What causes anything to have mass? The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Mass is the property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. It was assigned to the United States in 1889 and is periodically recertified and traceable to the primary international standard, The Kilogram, held at the Bureau International des Poids et... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... BIC pen cap, about 1 gram. ... A cubic centimetre (cm3) is an SI derived unit of volume, equal to the volume of a cube with side length of 1 centi metre. ... The surface gravity of a Killing horizon is the acceleration, as exerted at infinity, needed to keep an object at the horizon. ... Acceleration is the time rate of change of velocity, and at any point on a velocity-time graph, it is given by the slope of the tangent to that point basicly. ... A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre. ... The term g force or gee force refers to the symbol g, the force of acceleration due to gravity at the earths surface. ... Space Shuttle Atlantis launches on mission STS-71. ... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis. ... In astronomy, synchronous rotation is a planetological term describing a body orbiting another, where the orbiting body takes as long to rotate on its axis as it does to make one orbit; and therefore always keeps the same hemisphere pointed at the body it is orbiting. ... In astronomy, Axial tilt is the inclination angle of a planets rotational axis in relation to a perpendicular to its orbital plane. ... Albedo is the ratio of reflected to incident electromagnetic radiation. ... Fig. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... In ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. ... Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Deimos (IPA or ; Greek Δείμος: Dread), is the smaller and outermost of Mars’ two moons, named after Deimos from Greek Mythology. ... In Greek mythology, Phobos (fright) was the personification of fear and horror. ... In Greek mythology, Ares (Greek: ) is the son of Zeus (ruler of the gods) and Hera. ... The bust of Zeus found at Otricoli (Sala Rotonda, Museo Pio-Clementino, Vatican) Greek mythology is the body of stories belonging to the Ancient Greeks concerning their gods and heroes, the nature of the world and the origins and significance of their own cult and ritual practices. ... A kilometer (Commonwealth spelling: kilometre), symbol: km is a unit of length in the metric system equal to 1,000 metres (from the Greek words χίλια (khilia) = thousand and μέτρο (metro) = count/measure). ... A mile is a unit of length, usually used to measure distance, in a number of different systems, including Imperial units, United States customary units and Norwegian/Swedish mil. ...

Contents

Discovery

Phobos was discovered by American astronomer Asaph Hall, Sr., on August 18, 1877, at the US Naval Observatory in Washington, D.C., at about 09:14 GMT (contemporary sources, using the pre-1925 astronomical convention that began the day at noon, give the time of discovery as August 17 16:06 Washington mean time).[2][3][4] Hall also discovered Deimos, Mars' other moon. The discovery of the two moons of Mars, Phobos and Deimos, occurred in 1877 when American astronomer Asaph Hall, Sr. ... Asaph Hall (October 15, 1829 – November 22, 1907) was an American astronomer who is most famous for having discovered the moons of Mars (namely Deimos and Phobos) in 1877. ... August 18 is the 230th day of the year (231st in leap years) in the Gregorian calendar. ... 1877 (MDCCCLXXVII) was a common year starting on Monday (see link for calendar). ... Aerial view of USNO. The United States Naval Observatory (USNO) is one of the oldest scientific agencies in the United States. ... Nickname: Motto: Justitia Omnibus (Justice for All) Location of Washington, D.C., in relation to the states Maryland and Virginia Coordinates: Country United States Federal District District of Columbia Government  - Mayor Adrian M. Fenty (D)  - City Council Chairperson: Vincent C. Gray (D) Ward 1: Jim Graham (D) Ward 2: Jack... For alternate meanings of GMT, see GMT (disambiguation). ... August 17 is the 229th day of the year (230th in leap years) in the Gregorian calendar. ... Washington mean time was the time observed at the US Naval Observatory at Washington, D.C. It was sometimes called Washington meridian time. The modern-day observatory code for the US Naval Observatory (before 1893) is 787, and the longitude was 77. ... Deimos (IPA or ; Greek Δείμος: Dread), is the smaller and outermost of Mars’ two moons, named after Deimos from Greek Mythology. ...


The names, originally spelled Phobus and Deimus respectively, were suggested by Henry Madan (1838–1901), Science Master of Eton, from Book XV of the Iliad, where Ares summons Fear and Fright.[5] The Kings College of Our Lady of Eton beside Windsor, commonly known as Eton College or just Eton, is a public school (privately funded and independent) for boys, founded in 1440 by King Henry VI. It is located in Eton, Berkshire, near Windsor in England, situated north of Windsor... It has been suggested that Deception of Zeus be merged into this article or section. ... In Greek mythology, Ares (Greek: ) is the son of Zeus (ruler of the gods) and Hera. ...


Physical characteristics

A montage of three separate images taken by Viking 1 on October 19, 1978. The large crater (mostly in darkness) on the upper left of the image is the Stickney.
A montage of three separate images taken by Viking 1 on October 19, 1978. The large crater (mostly in darkness) on the upper left of the image is the Stickney.

Phobos is a dark body that appears to be composed of carbonaceous surface materials.[6] It is similar to the C-type asteroids.[7] Phobos' density is too low to be pure rock, however, and it is known to have significant porosity.[8][9][10] These results led to the suggestion that Phobos might contain a substantial reservoir of ice, but spectral observations have ruled out this hypothesis.[11] Download high resolution version (716x800, 49 KB)This image is a montage of three separate images taken by Viking 1 during one of its flybys of Phobos. ... Download high resolution version (716x800, 49 KB)This image is a montage of three separate images taken by Viking 1 during one of its flybys of Phobos. ... The Viking 1 was the first of two spacecraft sent to Mars as part of NASAs Viking program. ... October 19 is the 292nd day of the year (293rd in leap years) in the Gregorian calendar. ... Year 1978 (MCMLXXVIII) was a common year starting on Sunday (link displays the 1978 Gregorian calendar). ... Stickney crater (at left), with radiating grooves Stickney at top in sunlight, imaged by Mars Global Surveyor Stickney crater is the largest crater on Phobos, which is a satellite of Mars. ... Some carbonaceous chondrites. ... 253 Mathilde, a C-type asteroid. ... Porosity is a measure of the void spaces in a material, and is measured as a fraction, between 0–1, or as a percent between 0–100%. The term porosity is used in multiple fields including manufacturing, earth sciences and construction. ...


The Soviet spacecraft Phobos 2 reported a faint but steady release of dust particles from Phobos,[12] but the spacecraft failed before it could determine the nature of the material.[13] Recent images from Mars Global Surveyor indicate that Phobos is covered with a layer of fine-grained regolith at least 100 metres thick; it is believed to have been created by impacts from other bodies, but it is not known how the material stuck to an object with almost no gravity.[14] Soviet redirects here. ... The Phobos program was an unmanned space mission consisting of two probes launched by the Soviet Union to study Mars and its moons Phobos and Deimos. ... The Mars Global Surveyor (MGS) was a US spacecraft developed by NASA and the Jet Propulsion Laboratory and launched November 1996. ... Regolith (Greek: blanket rock) is a layer of loose, heterogeneous material covering solid rock. ...


Phobos is highly nonspherical, with dimensions of 27 × 21.6 × 18.8 km. Because of its shape alone, the gravity on its surface varies by about 210%; the tidal forces raised by Mars more than double this variation (to about 450%) because they compensate for a little more than half of Phobos' gravity at its sub- and anti-Mars poles.[citation needed]


Phobos is heavily cratered.[15] The most prominent surface feature is Stickney crater, named after Asaph Hall's wife, Angeline Stickney Hall, Stickney being her maiden name. Like Mimas's crater Herschel on a smaller scale, the impact that created Stickney must have almost shattered Phobos.[16] Many grooves and streaks also cover the oddly shaped surface. The grooves are typically less than 30 m deep, 100 to 200 m wide, and up to 20 km in length, and were originally assumed to have been the result of the same impact that created Stickney. Analysis of results from the Mars Express spacecraft, however, revealed that the grooves are in fact independent of Stickney, and are deposits of material thrown into space by impacts on the Martian surface.[17] Tycho crater on Earths moon. ... Stickney crater (at left), with radiating grooves Stickney at top in sunlight, imaged by Mars Global Surveyor Stickney crater is the largest crater on Phobos, which is a satellite of Mars. ... Chloe Angeline Stickney Hall Chloe Angeline Stickney Hall (November 1, 1830 – July 3, 1892) was the wife of astronomer Asaph Hall. ... Mimas (mee-məs or mye-məs, IPA: , Greek Μίμᾱς, rarely Μίμανς) is a moon of Saturn that was discovered in 1789 by William Herschel. ... Herschel is a huge crater on the Saturnian moon Mimas. ... Concept model of the Mars Express spacecraft Main Engine Thrust for braking manouevre Mars Express is a Mars exploration mission of the European Space Agency and the first planetary mission attempted by the agency. ...


The unique Kaidun meteorite is claimed to be a piece of Phobos, but this has been difficult to verify since little is known about the detailed composition of the moon.[18] The Kaidun meteorite is a meteorite that fell on March 12, 1980 on a Soviet military base in Yemen. ...


Orbital characteristics

Orbits of Phobos and Deimos (to scale), seen from above Mars' north pole
Orbits of Phobos and Deimos (to scale), seen from above Mars' north pole

Phobos's unusually close orbit around its parent planet produces some unusual effects. Image File history File links A simulated view of Naiad of the Orbits of Phobos and Deimos. ...


As seen from Phobos, Mars would appear 6400 times larger and 2500 times brighter than the full Moon appears from Earth, taking up a ¼ of the width of a celestial hemisphere. Apparent magnitude: up to -12. ...


Phobos orbits Mars below the synchronous orbit radius, meaning that it moves around Mars faster than Mars itself rotates. Therefore it rises in the west, moves comparatively rapidly across the sky (in 4 h 15 min or less) and sets in the east, approximately twice a day (every 11 h 6 min). Since it is close to the surface and in an equatorial orbit, it cannot be seen above the horizon from latitudes greater than 70.4°. A synchronous orbit is an orbit in which an orbiting body (usually a satellite) has a period equal to the average rotational period of the body being orbited (usually a planet), and in the same direction of rotation as that body. ... World map showing the equator in red In tourist areas, the equator is often marked on the sides of roads The equator marked as it crosses Ilhéu das Rolas, in São Tomé and Príncipe. ... Latitude, usually denoted symbolically by the Greek letter phi, , gives the location of a place on Earth north or south of the equator. ...


As seen from Mars' equator, Phobos would be one-third the angular diameter of the full Moon as seen from Earth. Observers at higher Martian latitudes would see a smaller angular diameter because they would be significantly farther away from Phobos. Phobos' apparent size would actually vary by up to 45% as it passed overhead, due to its proximity to Mars' surface: for an equatorial observer, for example, Phobos would be about 0.14° upon rising and swell to 0.20° by the time it reaches the zenith. By comparison, the Sun would have an apparent size of about 0.35° in the Martian sky. Apparent magnitude: up to -12. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... The Sun (Latin: Sol) is the star at the center of the Solar System. ...


Phobos' phases, inasmuch as they could be observed from Mars, take 0.3191 days to run their course (Phobos' synodic period), a mere 13 seconds longer than Phobos' sidereal period. The orbital period is the time it takes a planet (or another object) to make one full orbit. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ...


Solar transits

Phobos transits Sun, as seen by Mars Rover Opportunity
Phobos transits Sun, as seen by Mars Rover Opportunity

To an observer on the Martian surface, Phobos would regularly transit across the Sun. It is not large enough to cover the Sun's disk, and so cannot cause a total eclipse. Several of these transits have been photographed by the Mars Rover Opportunity. During the transits, Phobos's shadow is cast on the surface of Mars, and has been photographed by several spacecraft. Phobos transits the Sun, as seen by Mars Rover Opportunity on March 10, 2004 A transit of Phobos across the Sun as seen from Mars takes place when Phobos passes directly between the Sun and a point on the surface of Mars, obscuring a large part of the Suns... Image File history File links PIA05553. ... Image File history File links PIA05553. ... Phobos transits the Sun, as seen by Mars Rover Opportunity on March 10, 2004 A transit of Phobos across the Sun as seen from Mars takes place when Phobos passes directly between the Sun and a point on the surface of Mars, obscuring a large part of the Suns... MER-B (Opportunity) is the second of the two rovers of NASAs Mars Exploration Rover Mission. ... 2003 Transit of Mercury The term transit or astronomical transit has two meanings in astronomy: A transit is the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, as seen by an observer at some particular vantage point. ... For the 1995 film, see Total Eclipse (film). ... MER-B (Opportunity) is the second of the two rovers of NASAs Mars Exploration Rover Mission. ...


Death

Phobos' low orbit means that it will eventually be destroyed: tidal forces are lowering its orbit, currently at the rate of about 1.8 metres per century, and in 30-80 million years it will either impact the surface of Mars or (more likely) break up into a planetary ring. Given Phobos' irregular shape and assuming that it is a pile of rubble (specifically a Mohr-Coulomb body), it has been calculated that Phobos is stable with respect to tidal forces, but it is estimated that Phobos will pass the Roche Limit for a rubble pile when its orbital radius drops to about 7100 km, and will probably break up soon afterwards.[19] Comet Shoemaker-Levy 9 after breaking up under the influence of Jupiters tidal forces. ... A planetary ring is a ring of dust and other small particles orbiting around a planet in a flat disc-shaped region. ... In astronomy, rubble pile is the informal name for an asteroid that is not a monolith, consisting instead of numerous pieces of rock that have coalesced under the influence of gravity. ... Mohr-Coulomb Theory is a mathematical model describing the response of rubble piles to the shear forces produced by gravity. ... The Roche limit, sometimes referred to as the Roche radius, is the distance within which a celestial body held together only by its own gravity will disintegrate due to a second celestial bodys tidal forces exceeding the first bodys gravitational self-attraction. ... In astronomy, rubble pile is the informal name for an asteroid that is not a monolith, consisting instead of numerous pieces of rock that have coalesced under the influence of gravity. ...


Origin

Phobos and Deimos both have much in common with carbonaceous (C-type) asteroids, with very similar spectra, albedo and density to those seen in C-type asteroids.[7] This has led to speculation that both moons could have been captured into Martian orbit from the main asteroid belt.[20] However, both moons have very circular orbits which lie almost exactly in Mars' equatorial plane. Captured moons would be expected to have eccentric orbits in random inclinations. Some evidence suggests that Mars was once surrounded by many Phobos- and Deimos-sized bodies, perhaps ejected into orbit around it by a collision with a large planetesimal [21]. 253 Mathilde, a C-type asteroid. ... Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... Albedo is the ratio of reflected to incident electromagnetic radiation. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... For details on the physical properties of bodies in the asteroid belt see Asteroid and Main-belt comet. ... In astronomy and navigation, the celestial sphere is an imaginary rotating sphere of gigantic radius, concentric with the Earth. ... Planetesimals are solid objects thought to exist in protoplanetary disks and in debris disks. ...


"Hollow Phobos" claims

In the 1950 and 1960s, Phobos's unusual orbit and low density led to speculations that it might be a hollow artificial object.


Around 1958, Russian astrophysicist Iosif Samuilovich Shklovsky, studying the secular acceleration of Phobos' orbital motion, suggested a "thin sheet metal" structure for Phobos, a suggestion which led to speculations that Phobos was of artificial origin.[22] Shklovsky based his analysis on estimates of the upper Martian atmosphere's density, and deduced that for the weak braking effect to be able to account for the secular acceleration, Phobos had to be very light —one calculation yielded a hollow iron sphere 16 km across but less than 6 cm thick.[23] Year 1958 (MCMLVIII) was a common year starting on Wednesday (link will display full calendar) of the Gregorian calendar. ... Iosif Samuilovich Shklovsky (Ио́сиф Самуи́лович Шкло́вский) (July 1, 1916 – March 3, 1985) was a Soviet/Russian astronomer and astrophysicist. ... In astronomy, secular phenomena (which repeat too slowly to be observed, if at all) are contrasted with phenomena observed to repeat periodically. ...


In a February 1960 letter to the journal Astronautics,[24] Siegfried Frederick Singer, then science advisor to President Eisenhower, came out in support of Shklovsky's theory, going as far as to state that "[Phobos'] purpose would probably be to sweep up radiation in Mars' atmosphere, so that Martians could safely operate around their planet". A few years later, in 1963, Raymond H. Wilson Jr., Chief of Applied Mathematics at NASA, allegedly announced to the Institute of Aerospace Sciences that "Phobos might be a colossal base orbiting Mars", and that NASA itself was considering the possibility.[citation needed] Siegfried Frederick Singer (born September 27, 1924 in Vienna) is an atmospheric physicist. ... Dwight David Ike Eisenhower (October 14, 1890–March 28, 1969), American soldier and politician, was the 34th President of the United States (1953–1961) and supreme commander of the Allied forces in Europe during World War II, with the rank of General of the Army. ... Year 1963 (MCMLXIII) was a common year starting on Tuesday (link will display full calendar) of the Gregorian calendar. ... The National Aeronautics and Space Administration (NASA) is an agency of the United States federal government, responsible for the nations public space program. ...


Subsequently, however, the existence of the acceleration that had caused the claims was subjected to doubt,[25] and the problem vanished by 1969.[26] The earlier studies had used an overestimated value of 5 cm/yr for the rate of altitude loss, which was later revised to 1.8 cm/yr. The secular acceleration is now attributed to tidal effects, which had not been considered in the earlier studies. The density of Phobos is now measured to be 1.9 g/cm³, which is inconsistent with a hollow shell. In addition, images obtained by the Viking probes in the 1970s clearly showed a natural object, not an artificial one. For the Stargate SG-1 episode, see 1969 (Stargate SG-1). ... Viking mission profile. ... The 1970s decade refers to the years from 1970 to 1979. ...


Similar "hollow Moon" and "hollow Earth" claims have been made. A Hollow Earth theory posits that the planet Earth has a hollow interior and, possibly, a habitable inner surface. ...


Exploration

Past missions

Phobos has been photographed in close-up by several spacecraft whose primary mission has been to photograph Mars. The first was Mariner 9 in 1971, followed by Viking 1 in 1977, Mars Global Surveyor in 1998 and 2003, and Mars Express in 2004 . The only dedicated Phobos probes have been the Soviet Phobos 1 and Phobos 2; the first was lost en route to Mars, and the second returned some data and images before failing prior to its detailed examination of the moon. Adjectives: Martian Atmosphere Surface pressure: 0. ... Mariner 9 launch Mariner 9 was a NASA space probe orbiter that helped in the exploration of Mars and was part of the Mariner program. ... 1971 (MCMLXXI) was a common year starting on Friday. ... The Viking 1 was the first of two spacecraft sent to Mars as part of NASAs Viking program. ... Also: 1977 (album) by Ash. ... The Mars Global Surveyor (MGS) was a US spacecraft developed by NASA and the Jet Propulsion Laboratory and launched November 1996. ... 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... Concept model of the Mars Express spacecraft Main Engine Thrust for braking manouevre Mars Express is a Mars exploration mission of the European Space Agency and the first planetary mission attempted by the agency. ... The Phobos program was an unmanned space mission consisting of two probes launched by the Soviet Union to study Mars and its moons Phobos and Deimos. ... The Phobos program was an unmanned space mission consisting of two probes launched by the Soviet Union to study Mars and its moons Phobos and Deimos. ... Adjectives: Martian Atmosphere Surface pressure: 0. ...


Future missions

The Russian Space Agency is planning to launch a sample return mission to Phobos in 2009, called Phobos-Grunt. Chinese surveying equipement will be included.[27] The Russian Federal Space Agency, formerly the Russian Aviation and Space Agency (RKA) (in Russian: Российское авиационно-космическое аге&#1085... 2009 (MMIX) will be a common year starting on Thursday of the Gregorian calendar. ... Phobos-Grunt (rus. ...


Astrium in the UK is also planning a sample return mission.[28] ...


Named geological features

Geological features on Phobos are named after astronomers who studied Phobos and people and places from Jonathan Swift's Gulliver's Travels.[1] The only named ridge on Phobos is Kepler Dorsum, named after the astronomer Johannes Kepler. Several craters have been named.[2] An astronomer or astrophysicist is a person whose area of interest is astronomy or astrophysics. ... Jonathan Swift Jonathan Swift (November 30, 1667 – October 19, 1745) was an Irish cleric, satirist, essayist, political pamphleteer (first for Whigs then for Tories), and poet, famous for works like Gullivers Travels, A Modest Proposal, A Journal to Stella, The Drapiers Letters, The Battle of the Books, and... First Edition of Gullivers Travels Gullivers Travels (1726, amended 1735), officially Vol. ... Johannes Kepler (December 27, 1571 – November 15, 1630) was a German Lutheran mathematician, astronomer and astrologer, and a key figure in the 17th century astronomical revolution. ...

Crater Named after
Clustril Character in Gulliver's Travels
D'Arrest Heinrich Louis d'Arrest, astronomer
Drunlo Character in Gulliver's Travels
Flimnap Character in Gulliver's Travels
Gulliver Main character of Gulliver's Travels
Hall Asaph Hall, discoverer of Phobos
Limtoc Character in Gulliver's Travels
Reldresal Character in Gulliver's Travels
Roche Édouard Roche, astronomer
Sharpless Bevan Sharpless, astronomer
Skyresh Character in Gulliver's Travels
Stickney Angeline Stickney, wife of Asaph Hall
Todd David Peck Todd, astronomer
Wendell Oliver Wendell, astronomer

Heinrich Louis dArrest (July 13, 1822 – June 14, 1875) was a Prussian astronomer, born in Berlin. ... Asaph Hall (October 15, 1829 – November 22, 1907) was an American astronomer who is most famous for having discovered the moons of Mars (namely Deimos and Phobos) in 1877. ... Édouard Albert Roche (1820-1883) was a French scientist. ... Stickney crater (at left), with radiating grooves Stickney at top in sunlight, imaged by Mars Global Surveyor Stickney crater is the largest crater on Phobos, which is a satellite of Mars. ... Chloe Angeline Stickney Hall Chloe Angeline Stickney Hall (November 1, 1830 – July 3, 1892) was the wife of astronomer Asaph Hall. ... David Peck Todd (March 19, 1855 – June 1, 1939) was an American astronomer. ...

References

  1. ^ NASA Celestia
  2. ^ Notes: The Satellites of Mars 181–185. The Observatory, Vol. 1, No. 6 (September 20, 1877). Retrieved on September 12, 2006.
  3. ^ Hall, A. (October 17, 1877, signed September 21, 1877). Observations of the Satellites of Mars pp. 11/12–13/14. Astronomische Nachrichten, Vol. 91, No. 2161. Retrieved on September 12, 2006.
  4. ^ Morley, T. A.; A Catalogue of Ground-Based Astrometric Observations of the Martian Satellites, 1877-1982, Astronomy and Astrophysics Supplement Series (ISSN 0365-0138), Vol. 77, No. 2 (February 1989), pp. 209–226 (Table II, p. 220: first observation of Phobos on 1877-08-18.38498)
  5. ^ Hall, A. (March 14, 1878, signed February 7, 1878). Names of the Satellites of Mars 47-48. Astronomische Nachrichten, Vol. 92, No. 2187. Retrieved on September 12, 2006.
  6. ^ Lewis, J. S. (2004). Physics and Chemistry of the Solar System. Elsevier Academic Press, p. 425. ISBN 0-12-446744-X. 
  7. ^ a b Deimos.
  8. ^ Porosity of Small Bodies and a Reassesment of Ida's Density. “When the error bars are taken into account, only one of these, Phobos, has a porosity below 0.2...”
  9. ^ Close Inspection for Phobos. “It is light, with a density less than twice that of water, and orbits just 5989 km above the Martian surface.”
  10. ^ Busch, M. W.; et al.; 2007; Arecibo Radar Observations of Phobos and Deimos, Icarus, Vol. 196, pp. 581-584
  11. ^ Rivkin, A. S.; et al. (03 2002). "Near-Infrared Spectrophotometry of Phobos and Deimos". Icarus 156 (1): 64. 
  12. ^ Showalter, M. R.; Hamilton, D. P.; and Nicholson, P. D.. A Deep Search for Martian Dust Rings and Inner Moons Using the Hubble Space Telescope. Planetary and Space Science, Vol. 54 (2006), pp. 844–854.
  13. ^ Phobos 1 and 2 to Mars.
  14. ^ Forgotten Moons: Phobos and Deimos Eat Mars' Dust.
  15. ^ Phobos.
  16. ^ Stickney Crater-Phobos. “One of the most striking features of Phobos, aside from its irregular shape, is its giant crater Stickney. Because Phobos is only 28 by 20 kilometers (17 by 12 miles), the moon must have been nearly shattered from the force of the impact that caused the giant crater. Grooves that extend across the surface from Stickney appear to be surface fractures caused by the impact.”
  17. ^ Murray, J. B.; et al.. New Evidence on the Origin of Phobos’ Parallel Grooves from HRSC Mars Express. 37th Annual Lunar and Planetary Science Conference, March 2006.
  18. ^ The Kaidun Meteorite: Where Did It Come From?. “The currently available data on the lithologic composition of the Kaidun meteorite– primarily the composition of the main portion of the meteorite, corresponding to CR2 carbonaceous chondrites and the presence of clasts of deeply differentiated rock – provide weighty support for considering the meteorite’s parent body to be a carbonaceous chondrite satellite of a large differentiated planet. The only possible candidates in the modern solar system are Phobos and Deimos, the moons of Mars.”
  19. ^ Holsapple, K. A.; (2001); Equilibrium Configurations of Solid Cohesionless Bodies, Icarus, Vol. 154, pp. 432–448
  20. ^ Close Inspection for Phobos. “One idea is that Phobos and Deimos, Mars's other moon, are captured asteroids.”
  21. ^ Craddock, R. A.; (1994); The Origin of Phobos and Deimos, Abstracts of the 25th Annual Lunar and Planetary Science Conference, held in Houston, TX, 14-18 March 1994, p. 293
  22. ^ Shklovsky, I. S.; The Universe, Life, and Mind, Academy of Sciences USSR, Moscow, 1962
  23. ^ Öpik, E. J. (September 1964). Is Phobos Artificial? 281-283. Irish Astronomical Journal, Vol. 6. Retrieved on September 12, 2006.
  24. ^ Singer, S. F.; Astronautics, February 1960
  25. ^ Öpik, E. J. (March 1963, signed September 1962). News and Comments: Phobos, Nature of Acceleration p. 40. Irish Astronomical Journal, Vol. 6. Retrieved on September 12, 2006.
  26. ^ Singer, S. F. (1967). On the Origin of the Martian Satellites Phobos and Deimos. Seventh International Space Science Symposium held 10-18 May 1966 in Vienna, North-Holland Publishing Company.
  27. ^ Russia, China Could Sign Moon Exploration Pact in 2006. RIA Novosti (September 11, 2006). Retrieved on September 12, 2006.
  28. ^ Amos, J.; Martian Moon ’Could be Key Test’, BBC News (February 9, 2007)

September 12 is the 255th day of the year (256th in leap years) in the Gregorian calendar. ... For the Manfred Mann album, see 2006 (album). ... September 12 is the 255th day of the year (256th in leap years) in the Gregorian calendar. ... For the Manfred Mann album, see 2006 (album). ... September 12 is the 255th day of the year (256th in leap years) in the Gregorian calendar. ... For the Manfred Mann album, see 2006 (album). ... John S. Lewis is a professor of planetary science at the University of Arizona’s Lunar and Planetary Laboratory. ... Ernst Julius Öpik Ernst Julius Öpik (October 23, 1893 – September 10, 1985) was a notable Estonian astronomer and astrophysicist, who spent the last part of his career (1948–1981) at the Armagh Observatory in Northern Ireland. ... September 12 is the 255th day of the year (256th in leap years) in the Gregorian calendar. ... For the Manfred Mann album, see 2006 (album). ... Siegfried Frederick Singer (born September 27, 1924 in Vienna) is an atmospheric physicist. ... September 12 is the 255th day of the year (256th in leap years) in the Gregorian calendar. ... For the Manfred Mann album, see 2006 (album). ... RIA (Russian Information Agency) Novosti is a Russian press agency based in Moscow. ... September 12 is the 255th day of the year (256th in leap years) in the Gregorian calendar. ... For the Manfred Mann album, see 2006 (album). ... February 9 is the 40th day of the year in the Gregorian calendar. ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ...

See also

Phobos transits the Sun, as seen by Mars Rover Opportunity on March 10, 2004 A transit of Phobos across the Sun as seen from Mars takes place when Phobos passes directly between the Sun and a point on the surface of Mars, obscuring a large part of the Suns... The satellite Phobos orbits very close to Mars and casts a penumbral shadow on the Martian surface. ... Phobos and Deimos, the two moons of Mars, are locations frequently mentioned in works of science fiction. ... The space program of the Peoples Republic of China (PRC) began in 1956 with the cooperation of the USSR and continued as an indigenous nuclear deterrent program after the Sino-Soviet split in 1960. ...

External links

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Phobos
 v  d  e The Solar System
The Sun Mercury Venus The Moon Earth Phobos and Deimos Mars Ceres The asteroid belt Jupiter Jupiter's natural satellites Saturn Saturn's natural satellites Uranus Uranus' natural satellites Neptune's natural satellites Neptune Charon, Nix, and Hydra Pluto The Kuiper belt Dysnomia Eris The scattered disc The Oort cloud
The Sun · Mercury · Venus · Earth · Mars · Ceres · Jupiter · Saturn · Uranus · Neptune · Pluto · Eris
Planets · Dwarf planets · Moons: Terrestrial · Martian · Jovian · Saturnian · Uranian · Neptunian · Plutonian · Eridian
Small bodies:   Meteoroids · Asteroids/Asteroid moons (Asteroid belt) · Centaurs · TNOs (Kuiper belt/Scattered disc) · Comets (Oort cloud)
See also astronomical objects, the solar system's list of objects, sorted by radius or mass, and the Solar System Portal

  Results from FactBites:
 
Phobos (moon) - Wikipedia, the free encyclopedia (1913 words)
Phobos was photographed close-up by Mariner 9 in 1971, Viking 1 in 1977, Phobos 2 in 1988, Mars Global Surveyor in 1998 and 2003, and by Mars Express in 2004.
Later the moon is overtaken by multinational forces and is de-orbited by the Martian rebels.
Phobos is the final mission in the video game Armored Core 2 where the player must battle to the center to destroy the orbit control mechanism and prevent it from crashing into Mars and destroying the newly formed Martian civilization.
Phobos - Wikipedia, the free encyclopedia (177 words)
Phobos (mythology), one of the sons of Ares and Aphrodite in Greek mythology.
Phobos (moon), the larger and innermost of Mars' two moons.
Phobos program, consisting of two unmanned probes, Phobos 1 and Phobos 2, sent to Mars by the Soviet Union.
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