Phobos ( , or as Greek
Φόβος) (
systematic designationIn ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered every year...
:
) is the larger and closer of two small
moonA natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called the primary. Technically, the term natural satellite could refer to a planet orbiting a star, or a dwarf galaxy orbiting a major galaxy, but it is normally synonymous with moon and used to identify...
s of
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
, the other being
DeimosDeimos , is the smaller and outer of Mars’ two moons . It is named after Deimos, a figure representing dread in Greek Mythology. Its systematic designation is '.-Discovery:...
. It is named after the
Greek godGreek mythology is the body of myths and legends 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. They were a part of religion in ancient Greece...
PhobosPhobos is the embodiment of fear and horror in Greek mythology. He is the offspring of Ares and Aphrodite. He was known for accompanying Ares into battle along with his brother, Deimos, the goddess Enyo, and his father’s attendants. Timor is his Roman equivalent.-Genealogy:Phobos is the son of...
(which means "fear"), a son of
AresIn Greek mythology, Ares is the son of Zeus and Hera. Though often referred to as the Olympian god of warfare, he is more accurately the god of bloodlust, or slaughter personified: "Ares is apparently an ancient abstract noun meaning throng of battle, war."-Etymology:Ares is the god of war...
(Mars). A small, irregularly shaped object, Phobos orbits about km (5827 mi) from the center of Mars, closer to its primary than any other known planetary moon.
Discovery
Phobos was discovered by astronomer
Asaph Hall, Sr.Asaph Hall III was an American astronomer who is most famous for having discovered the moons of Mars in 1877...
, on August 18, 1877, at the
United States Naval ObservatoryThe United States Naval Observatory is one of the oldest scientific agencies in the United States, with a primary mission to produce Positioning, Navigation, and Timing for the U.S. Navy and the U.S. Department of Defense...
in
Washington, D.C.Washington, D.C. , formally the District of Columbia and commonly referred to as Washington, the District, or simply D.C., is the capital of the United States, founded on July 16, 1790...
, at about 09:14
Greenwich Mean TimeGreenwich Mean Time is a term originally referring to mean solar time at the Royal Observatory in Greenwich, London. It is commonly used in practice to refer to Coordinated Universal Time when this is viewed as a time zone, especially by bodies connected with the United Kingdom, such as the BBC...
(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 timeWashington mean time was the time at the meridian through the center of the old dome atop the main building at the old US Naval Observatory at Washington, D.C. This Washington meridian was defined on 28 September 1850 by the United States Congress...
). Hall also discovered
DeimosDeimos , is the smaller and outer of Mars’ two moons . It is named after Deimos, a figure representing dread in Greek Mythology. Its systematic designation is '.-Discovery:...
, Mars' other moon.
The names, originally spelled
Phobus and
Deimus respectively, were suggested by Henry Madan (1838–1901), Science Master of
EtonEton College, often referred to simply as Eton, is a British independent boarding school for boys aged approx. 13 to 19. It was founded in 1440 by King Henry VI as "The King's College of Our Lady of Eton besides Wyndsor"....
, from Book XV of the
IliadThe Iliad is an epic poem recounting significant events during a portion of the final year of the Trojan War — the Greek siege of the city of Ilion — hence the title...
, where
AresIn Greek mythology, Ares is the son of Zeus and Hera. Though often referred to as the Olympian god of warfare, he is more accurately the god of bloodlust, or slaughter personified: "Ares is apparently an ancient abstract noun meaning throng of battle, war."-Etymology:Ares is the god of war...
summons Dread (
DeimosIn Greek mythology, Deimos was the personification of dread.He was the son of Ares and Aphrodite. He, his twin brother Phobos and the goddess Enyo accompanied Ares into battle, as well as his father's attendants, Trembling, Fear, Dread, and Panic...
) and Fear (
PhobosPhobos is the embodiment of fear and horror in Greek mythology. He is the offspring of Ares and Aphrodite. He was known for accompanying Ares into battle along with his brother, Deimos, the goddess Enyo, and his father’s attendants. Timor is his Roman equivalent.-Genealogy:Phobos is the son of...
).
Physical characteristics
Phobos is one of the least-reflective bodies in the solar system. Spectroscopically it appears to be similar to the D-type
asteroidthumb|260px|right|[[253 Mathilde]], a [[C-type asteroid]] measuring about across. Photograph taken in 1997 by the [[NEAR Shoemaker]] probe.Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, especially in the inner Solar System; they are...
s, and is apparently of composition similar to
carbonaceous chondriteCarbonaceous chondrites or C chondrites are a class of chondritic meteorites comprising at least 7 known groups and many ungrouped meteorites. They include some of the most primitive known meteorites...
material. Phobos' density is too low to be solid rock, however, and it is known to have significant
porosityPorosity is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
. These results led to the suggestion that Phobos might contain a substantial reservoir of ice. Spectral observations indicate that the surface
regolithRegolith is a layer of loose, heterogeneous material covering solid rock. The term is a combination of two Greek words: Rhegos , which means blanket, and Lithos , which means rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids,...
layer lacks hydration, but ice below the regolith is not ruled out.
Faint dust rings produced by Phobos and Deimos have long been predicted but attempts to observe these rings have, to date, failed. Recent images from
Mars Global SurveyorThe Mars Global Surveyor was a US spacecraft developed by NASA's Jet Propulsion Laboratory and launched November 1996. It began the United States's return to Mars after a 10-year absence. It completed its primary mission in January 2001 and was in its third extended mission phase when, on , the...
indicate that Phobos is covered with a layer of fine-grained
regolithRegolith is a layer of loose, heterogeneous material covering solid rock. The term is a combination of two Greek words: Rhegos , which means blanket, and Lithos , which means rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids,...
at least 100 meters 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.
Phobos is highly nonspherical, with dimensions of 27 × 22 × 18 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's gravity at its sub- and anti-Mars poles.
Phobos is heavily
craterIn the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
ed. The most prominent surface feature is Stickney crater, named after Asaph Hall's wife,
Angeline Stickney HallChloe Angeline Stickney Hall suffragist, abolitionist, and mathematician, was the wife of astronomer Asaph Hall...
, Stickney being her maiden name. Like
MimasMimas is a moon of Saturn which was discovered in 1789 by William Herschel. It is named after Mimas, a son of Gaia in Greek mythology, and is also designated Saturn I....
's crater
HerschelHerschel is a huge crater on the Saturnian moon Mimas. It is named after the eighteenth century astronomer William Herschel, who discovered Mimas in 1789....
on a smaller scale, the impact that created Stickney must have almost shattered Phobos. 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 ExpressMars Express is a space exploration mission being conducted by the European Space Agency . The Mars Express mission is exploring the planet Mars, and is the first planetary mission attempted by the agency. "Express" originally referred to the speed and efficiency with which the spacecraft was...
spacecraft, however, revealed that the grooves are not in fact radial to Stickney, but are centered on the leading apex of Phobos in its orbit (which is not far from Stickney). Researchers believe they have been excavated by material ejected into space by impacts on the surface of Mars. The grooves thus formed as
crater chainA crater chain is a line of craters along the surface of an astronomical body. The descriptor term for crater chains is catena , as specified by the International Astronomical Union's rules on planetary nomenclature....
s, and all of them fade away as the trailing apex of Phobos is approached. They have been grouped into 12 or more families of varying age, presumably representing at least 12 Martian impact events.
The unique
Kaidun meteoriteThe Kaidun meteorite is a meteorite that fell on 3 December 1980 on a Soviet military base near what is now Al-Khuraybah in Yemen. A fireball was observed travelling from the Northwest to the Southeast, and a single stone weighing about was recovered from a small impact pit...
is thought to be a piece of Phobos, but this has been difficult to verify since little is known about the detailed composition of the moon.
Orbital characteristics
Phobos's unusually close orbit around its parent planet produces some unusual effects.
As seen from Phobos, Mars would appear times larger and times brighter than the full
MoonThe Moon is Earth's only natural satellite and the fifth largest satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is , about thirty times the diameter of the Earth. The common centre of mass of the system is located at about —a quarter the Earth's...
appears from Earth, taking up a quarter of the width of a celestial hemisphere.
Phobos orbits Mars below the
synchronous orbitA synchronous orbit is an orbit in which an orbiting body has a period equal to the average rotational period of the body being orbited , and in the same direction of rotation as that body.-Properties:...
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 each Martian day (every 11 h 6 min). Since it is close to the surface and in an
equatorThe equator is the intersection of the Earth's surface with the plane perpendicular to the Earth's axis of rotation and containing the Earth's center of mass. In simpler language, it is an imaginary line on the Earth's surface equidistant from the North Pole and South Pole that divides the Earth...
ial orbit, it cannot be seen above the horizon from
latitudeLatitude, usually denoted by the Greek letter phi gives the location of a place on Earth north or south of the equator. Lines of Latitude are the imaginary horizontal lines shown running east-to-west on maps that run either north or south of the equator...
s greater than 70.4°.
Phobos's orbit is so low that its
angular diameterThe angular diameter or apparent size of an object as seen from a given position is the “visual diameter” of the object measured as an angle. In the vision sciences it is called the visual angle. The visual diameter is the diameter of the perspective projection of the object on a plane through its...
, as seen by an observer on Mars, varies visibly with its position in the sky. Seen at the horizon, Phobos is about 0.14° wide; at
zenithIn general terms, the zenith is the direction pointing directly "above" a particular location; that is, it is one of two vertical directions at the location, orthogonal to a horizontal flat surface there...
it is 0.20°, one-third as wide as the full
MoonThe Moon is Earth's only natural satellite and the fifth largest satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is , about thirty times the diameter of the Earth. The common centre of mass of the system is located at about —a quarter the Earth's...
as seen from
EarthEarth is the third planet from the Sun. It is the fifth largest of the eight planets in the solar system, and the largest of the terrestrial planets in the Solar System in terms of diameter, mass and density...
. By comparison, the
SunThe Sun is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass....
has an apparent size of about 0.35° in the Martian sky.
Phobos's phases, inasmuch as they can be observed from Mars, take 0.3191 days (Phobos's synodic period) to run their course, a mere 13 seconds longer than Phobos's sidereal period.
Solar transits
An observer situated on the Martian surface in a position to observe Phobos would see regular
transitsThe term transit or astronomical transit has three 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.* A transit occurs when a celestial...
of the moon across the Sun. Phobos is not large enough to cover the Sun's disk, and so cannot cause a
total eclipseA total eclipse is an eclipse where either the Sun is entirely covered by the Moon, or the Earth's shadow entirely covers the Moon.Total Eclipse may also refer to:-Music:* Total Eclipse , a Goa trance music group...
. 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, which has been photographed by several spacecraft.
Future destruction
Because Phobos's orbital period is shorter than a Martian day, tidal locking is decreasing its orbital radius at the rate of about 20 meters per century. In 11 million years it will either impact the surface of Mars or more likely break up into a
planetary ringA planetary ring is a ring of cosmic dust and other small particles orbiting around a planet in a flat disc-shaped region.The most spectacular planetary rings known are those around Saturn, but the other three gas giants of the solar system possess ring systems of their own.Recent reports have...
. Given Phobos's irregular shape and assuming that it is a
pile of rubbleIn 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...
(specifically a
Mohr-Coulomb bodyMohr-Coulomb theory is a mathematical model describing the response of brittle materials such as concrete, or rubble piles, to shear stress as well as normal stress. Most of the classical engineering materials somehow follow this rule in at least a portion of their shear failure envelope...
), it has been calculated that Phobos is currently stable with respect to tidal forces. But it is estimated that Phobos will pass the
Roche LimitThe 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 body's tidal forces exceeding the first body's gravitational self-attraction...
for a rubble pile when its orbital radius drops by a little over km to about km. At this distance Phobos will likely begin to break up and form a short lived ring system around Mars. The rings themselves will then continue to spiral slowly into Mars.
Origin
The origin of the Martian moons is still controversial. Phobos and Deimos both have much in common with carbonaceous
C-type asteroidthumb|right|[[253 Mathilde]], a C-type asteroidC-type asteroids are carbonaceous asteroids. They are the most common variety forming around 75% of known asteroids, and an even higher percentage in the outer part of the belt beyond 2.7 AU, which is dominated by this asteroid type...
s, with
spectraThe electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
,
albedoThe albedo of an object is the extent to which it diffusely reflects light from light sources such as the Sun. It is therefore a more specific form of the term reflectivity. Albedo is defined as the ratio of diffusely reflected to incident electromagnetic radiation. It is a unitless measure...
s and
densitiesThe density of a material is defined as its mass per unit volume. The symbol of density is ρ .- Formula :Mathematically:where: is the density, is the mass, is the volume....
very similar to those of C- or D-type asteroids. Based on this similarity, one hypothesis is that both moons may have been captured into Martian orbit from the main
asteroid beltThe asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
. Both moons have very circular orbits which lie almost exactly in Mars's equatorial plane, and hence a capture origin requires a mechanism for circularizing the initially highly eccentric orbit, and adjusting its inclination into the equatorial plane, most likely by a combination of atmospheric drag and
tidal forceThe tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational force exerted on one body by a second body is not constant across its diameter...
s, although it is not clear that sufficient time is available for this to occur for Deimos. Capture also requires dissipation of energy. The current Mars atmosphere is too thin to capture a Phobos-sized object by atmospheric braking.
Geoffrey LandisGeoffrey A. Landis works as a scientist and writer of science fiction.Landis holds undergraduate degrees in physics and electrical engineering from MIT and a Ph.D. in solid-state physics from Brown University. He works for the NASA John Glenn Research Center, where he does research on Mars...
has pointed out that the capture could have occurred if the original body was a
binary asteroidA binary asteroid is a system of two asteroids orbiting their common center of mass, in analogy with binary stars. 243 Ida was the first binary asteroid to be identified when the Galileo spacecraft did a flyby in 1993...
that separated under tidal forces. The main alternative hypothesis is that the moons accreted in the present position. Another hypothesis is that Mars was once surrounded by many Phobos- and Deimos-sized bodies, perhaps ejected into orbit around it by a collision with a large
planetesimalPlanetesimals are solid objects thought to exist in protoplanetary disks and in debris disks.A widely accepted theory of planet formation, the so-called planetesimal hypothesis of Viktor Safronov, states that planets form out of dust grains that collide and stick to form larger and larger bodies...
.
"Hollow Phobos" suggestions
In the late 1950s and 1960s, the unusual orbital characteristics of Phobos led to speculations that it might be hollow.
Around 1958, Russian astrophysicist Iosif Samuilovich Shklovsky, studying the
secularIn astronomy, secular phenomena are contrasted with phenomena observed to repeat periodically. In particular, astronomical ephemerides use secular to label long-term perturbations in the motion of planets, as opposed to periodic perturbations....
accelerationIn physics, and more specifically kinematics, acceleration is the change in velocity over time. Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, i.e. a line, acceleration is the rate at which something speeds up or slows...
of Phobos's orbital motion, suggested a "thin sheet metal" structure for Phobos, a suggestion which led to speculations that Phobos was of artificial origin. 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. In a February 1960 letter to the journal
Astronautics,
S. Fred SingerSiegfried Frederick Singer is an American atmospheric physicist. Singer is Professor Emeritus of environmental science at the University of Virginia, specializing in planetary science, global warming, ozone depletion, and other global environmental issues.In the 1960s Singer was a leading figure...
, then science advisor to U.S. President
Dwight D. EisenhowerDwight David "Ike" Eisenhower was a five-star general in the United States Army and the 34th President of the United States, from 1953 until 1961. During the Second World War, he served as Supreme Commander of the Allied forces in Europe, with responsibility for planning and supervising the...
, came out in support of Shklovsky's theory, stating:
[Phobos'] purpose would probably be to sweep up radiation in Mars' atmosphere, so that Martians could safely operate around their planet.
My conclusion there is, and here I back Shklovsky, that if the satellite is indeed spiraling inward as deduced from astronomical observation, then there is little alternative to the hypothesis that it is hollow and therefore martian made. The big 'if' lies in the astronomical observations; they may well be in error. Since they are based on several independent sets of measurements taken decades apart by different observers with different instruments, systematic errors may have influenced them.
Subsequently, however, the existence of the acceleration that had caused the claims was called into doubt, and accurate measurements of the orbit available by 1969 showed that the discrepancy did not exist. Singer's critique was justified when earlier studies were later discovered to have 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 has now been directly measured by spacecraft to be 1.887 g/cm³, which is inconsistent with a hollow shell. In addition, images obtained by the
Viking probesNASA's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. Each vehicle was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...
in the 1970s clearly showed a natural object, not an artificial one, and the "hollow Phobos" speculations have been relegated to the status of a historical curiosity.
Past missions
Phobos has been photographed in close-up by several spacecraft whose primary mission has been to photograph
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
. The first was
Mariner 9Mariner 9 was a NASA space probe orbiter that helped in the exploration of Mars and was part of the Mariner program...
in 1971, followed by
Viking 1Viking 1 was the first of two spacecraft sent to Mars as part of NASA's Viking program. It was the first spacecraft to successfully land on Mars and perform its mission, and holds the record for the longest Mars surface mission of 6 years and 116 days .- Mission :Following launch using a...
in 1977,
Mars Global SurveyorThe Mars Global Surveyor was a US spacecraft developed by NASA's Jet Propulsion Laboratory and launched November 1996. It began the United States's return to Mars after a 10-year absence. It completed its primary mission in January 2001 and was in its third extended mission phase when, on , the...
in 1998 and 2003,
Mars ExpressMars Express is a space exploration mission being conducted by the European Space Agency . The Mars Express mission is exploring the planet Mars, and is the first planetary mission attempted by the agency. "Express" originally referred to the speed and efficiency with which the spacecraft was...
in 2004 and 2008, and
Mars Reconnaissance OrbiterNASA's Mars Reconnaissance Orbiter is a multipurpose spacecraft designed to conduct reconnaissance and exploration of Mars from orbit....
in 2007 and 2008. The only dedicated Phobos probes have been the Soviet
Phobos 1 and
Phobos 2; the first was lost en route to
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
, and the second returned documented, unusual data and images before failing before its detailed examination of the moon.
Future missions
The Russian Space Agency is planning to launch a sample return mission to Phobos in 2011, called
Phobos-GruntPhobos-Grunt is a planned Russian sample return mission to Phobos, one of the moons of Mars. The Chinese Mars orbiter Yinghuo-1 will be sent together with the mission. Scheduled for launch in 2011, Phobos-Grunt will be the first Russian interplanetary mission since the failed Mars 96 mission...
. The return capsule will include a life science experiment of The Planetary Society, called
Living Interplanetary Flight ExperimentThe Living Interplanetary Flight Experiment is an interplanetary mission being developed by the Planetary Society. It will consist of sending selected microorganisms on a three-year interplanetary round-trip in a small capsule aboard the Russian Phobos-Grunt spacecraft in 2011, which is a...
, or LIFE.
A second contributor to this mission is China with a surveying satellite called "Yinghuo-1" that will be released in the orbit of Mars, and a soil grinding and sieving system for the scientific payload of the Phobos lander.
Astrium in the UK is also planning a sample return mission.
In 2007 the
Canadian Space AgencyThe Canadian Space Agency is the Canadian government space agency responsible for Canada's space program. It was established in March 1989 by the Canadian Space Agency Act and sanctioned in December 1990...
funded a study by
OptechOptech Incorporated is a Canadian-owned for-profit company operating since 1974 and focusing on Laser-based survey systems.Optech Inc is known for its association with Phoenix, a spacecraft launched for Mars in 2007.- The company :...
and the
Mars InstituteThe Mars Institute is an international non-governmental organization created with the goals of advancing the scientific study and exploration of Mars, conducting high-quality, peer-reviewed research, and educating the public on the progress toward and benefits of Mars exploration. It was...
for an unmanned mission to Phobos known as PRIME (Phobos Reconnaissance and International Mars Exploration). A proposed landing site for the PRIME spacecraft is the "
Phobos MonolithThe Phobos monolith is a surface feature on the Mars moon Phobos. It is a bright object near Stickney crater which casts a prominent shadow. It was discovered by Efrain Palermo, who did large surveys of Martian probe imagery, and confirmed by Lan Fleming, an imaging sub-contractor at NASA Johnson...
," a bright object near Stickney which casts a prominent shadow. The PRIME mission would be composed of an orbiter and lander, and each would carry 4 instruments designed to study various aspects of Phobos's geology. At present, PRIME does not have a projected launch date.
Astronaut
Buzz AldrinBuzz Aldrin is an American mechanical engineer, retired United States Air Force pilot and astronaut who was the Lunar Module pilot on Apollo 11, the first lunar landing...
referred to this "
monolithA monolith is a geological feature such as a mountain, consisting of a single massive stone or rock, or a single piece of rock placed as, or within, a monument...
" in a July 22, 2009 interview with
C-SpanC-SPAN , an abbreviation of Cable-Satellite Public Affairs Network, is an American cable television network dedicated to airing non-stop coverage of government proceedings and public affairs programming...
: "We should go boldly where man has not gone before. Fly by the comets, visit asteroids, visit the moon of Mars. There’s a monolith there. A very unusual structure on this potato shaped object that goes around Mars once in seven hours. When people find out about that they’re going to say ‘Who put that there? Who put that there?’ The universe put it there. If you choose, God put it there…”
Phobos has also been proposed as an early target for a
manned mission to MarsA manned mission to Mars has not taken place but is the subject of science fiction, engineering, and scientific proposals and plans throughout the 20th Century and into the 21st Century...
, since a landing on Phobos would be considerably less difficult (and hence, much less expensive) than a landing on the surface of Mars itself. A lander bound for Mars would need to be capable of atmospheric entry and subsequent in-situ return to orbit without any support facilities (a capacity which has never been attempted in a manned spacecraft), or would require the creation of support facilities in-situ (a "colony or bust" mission), while a lander intended for Phobos could be based on equipment designed for lunar and asteroid landings.
Named geological features
Geological features on Phobos are named after
astronomerAn astronomer is a scientist who studies celestial bodies such as planets, stars, and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
s who studied Phobos and people and places from
Jonathan SwiftJonathan Swift was an Anglo-Irish satirist, essayist, political pamphleteer , poet and cleric who became Dean of St...
's
Gulliver's TravelsGulliver's Travels , officially Travels into Several Remote Nations of the World, in Four Parts. By Lemuel Gulliver, First a Surgeon, and then a Captain of several Ships, is a novel by Irish writer and clergyman Jonathan Swift that is both a satire on human nature and a parody of the "travellers'...
. The only named ridge on Phobos is Kepler Dorsum, named after the astronomer
Johannes KeplerJohannes Kepler was a German mathematician, astronomer and astrologer, and key figure in the 17th century scientific revolution. He is best known for his eponymous laws of planetary motion, codified by later astronomers based on his works Astronomia nova, Harmonices Mundi, and Epitome of...
. Several craters have been named.
| Crater | Named after |
|---|
| Clustril |
Character in Gulliver's Travels |
| D'Arrest |
Heinrich Louis d'ArrestHeinrich Louis d'Arrest was a German astronomer, born in Berlin. His name is sometimes given as Heinrich Ludwig d'Arrest....
, astronomer |
| Drunlo |
Character in Gulliver's Travels |
| Flimnap |
Character in Gulliver's Travels |
| Grildrig |
Character in Gulliver's Travels |
| Gulliver |
Main character of Gulliver's Travels |
| Hall |
Asaph HallAsaph Hall III was an American astronomer who is most famous for having discovered the moons of Mars in 1877...
, discoverer of Phobos |
| Limtoc |
Character in Gulliver's Travels |
| Reldresal |
Character in Gulliver's Travels |
| Roche |
Édouard Roche Édouard Albert Roche was a French astronomer and mathematician, who is best known for his work in the field of celestial mechanics...
, astronomer |
| Sharpless |
Bevan Sharpless, astronomer |
| Skyresh |
Character in Gulliver's Travels |
| Stickney Stickney crater is the largest crater on Phobos, which is a satellite of Mars. It is located at 5°S 55°W on Phobos and is in diameter, taking up a substantial proportion of the moon's surface....
|
Angeline Stickney Chloe Angeline Stickney Hall suffragist, abolitionist, and mathematician, was the wife of astronomer Asaph Hall...
, wife of Asaph Hall |
| Todd |
David Peck Todd David Peck Todd was a noted American astronomer. He produced a complete set of photographs of the 1882 transit of Venus.-Biography:...
, astronomer |
| Wendell |
Oliver Wendell, astronomer |
See also
- Phobos and Deimos in fiction
Phobos and Deimos, the two moons of Mars, are locations frequently mentioned in works of science fiction.- Phobos :*In part 3 chapter 3 of Jonathan Swift's famous satire Gulliver's Travels, a fictional work written in 1726, the astronomers of Laputa are described as having discovered two...
- Phobos-Grunt
Phobos-Grunt is a planned Russian sample return mission to Phobos, one of the moons of Mars. The Chinese Mars orbiter Yinghuo-1 will be sent together with the mission. Scheduled for launch in 2011, Phobos-Grunt will be the first Russian interplanetary mission since the failed Mars 96 mission...
mission
- Transit of Phobos from Mars
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 Sun's disc for an observer on Mars. During a transit, Phobos can be seen from Mars as a large black disc rapidly moving...
External links