Deimos (moon)
Synchronous[5] | |
Albedo | 0.068±0.007[9] |
---|---|
Temperature | ≈ 233 K |
12.89[10] | |
Deimos /ˈdaɪməs/ (systematic designation: Mars II)[11] is the smaller and outer of the two natural satellites of Mars, the other being Phobos. Deimos has a mean radius of 6.2 km (3.9 mi) and takes 30.3 hours to orbit Mars.[5] Deimos is 23,460 km (14,580 mi) from Mars, much farther than Mars's other moon, Phobos.[12] It is named after Deimos, the Ancient Greek god and personification of dread and terror.
Discovery and Etymology
Deimos was discovered by Asaph Hall at the United States Naval Observatory in Washington, D.C., on 12 August 1877, at about 07:48 UTC.[a] Hall, who also discovered Phobos shortly afterwards, had been specifically searching for Martian moons at the time.
The moon is named after Deimos, a figure representing dread in Greek mythology.[11] The name was suggested by academic Henry Madan, who drew from Book XV of the Iliad, where Ares (Greek counterpart of the Roman god Mars) summons Dread (Deimos) and Fear (Phobos).[18]
Origin
The origin of Mars's moons is unknown and the hypotheses are controversial.[19] The main hypotheses are that they formed either by capture or by accretion.
Because of the postulated similarity to the composition of
In 2021, Amirhossein Bagheri (ETH Zurich), Amir Khan (ETH Zurich), Michael Efroimsky (US Naval Observatory) and their colleagues proposed a new hypothesis on the origin of the moons. By analyzing the seismic and orbital data from the Mars InSight Mission and other missions, they proposed that the moons were born from the disruption of a common parent body around 1 to 2.7 billion years ago. The common progenitor of Phobos and Deimos was most probably hit by another object and shattered to form Phobos and Deimos.[24]
Physical characteristics
Like most bodies of its size, Deimos is highly non-spherical with triaxial dimensions of 16.1 km × 11.8 km × 10.2 km (10.0 mi × 7.3 mi × 6.3 mi), corresponding to a mean diameter of 12.5 km (7.8 mi) which makes it about 57% the size of Phobos.[7] Deimos is composed of rock rich in carbonaceous material, much like C-type asteroids and carbonaceous chondrite meteorites.[25] It is cratered, but the surface is noticeably smoother than that of Phobos, caused by the partial filling of craters with regolith.[citation needed] The regolith is highly porous and has a radar-estimated density of only 1.471 g/cm3.[26]
Escape velocity from Deimos is 5.6 m/s.[6] This velocity could theoretically be achieved by a human performing a vertical jump.[27][28] The apparent magnitude of Deimos is 12.45.[9]
Named geological features
Only two geological features on Deimos have been given names. The craters Swift and Voltaire are named after writers who speculated on the existence of two Martian moons before Phobos and Deimos were discovered.[29]
Craters | Coordinates | Diameter (km) |
Approval Year |
Eponym | Ref |
---|---|---|---|---|---|
Swift | 12°30′N 1°48′E / 12.5°N 1.8°E | 1 | 1973 | Jonathan Swift; Irish writer (1667–1745) | WGPSN |
Voltaire | 22°00′N 3°30′W / 22°N 3.5°W | 1.9 | 1973 | Voltaire; French writer (1694–1778) | WGPSN |
Orbital characteristics
Deimos's
As seen from Mars, Deimos would have an
Unlike Phobos, which orbits so fast that it rises in the west and sets in the east, Deimos rises in the east and sets in the west, slower than Mars's rotation speed. The Sun-synodic orbital period of Deimos of about 30.4 hours exceeds the Martian solar day ("sol") of about 24.7 hours by such a small amount that 2.48 days (2.41 sols) elapse between its rising and setting for an equatorial observer. From Deimos-rise to Deimos-rise (or setting to setting), 5.466 days (5.320 sols) elapse.[citation needed]
Because Deimos's orbit is relatively close to Mars and has only a very small inclination to Mars's equator, it cannot be seen from Martian latitudes greater than 82.7°.[citation needed]
Deimos's orbit is slowly getting larger, because it is far enough away from Mars and because of tidal acceleration. It is expected to eventually escape Mars's gravity.[33]
Solar transits
Deimos regularly
March 5, 2024: NASA released images of transits of the moon Deimos, the moon Phobos and the planet Mercury as viewed by the Perseverance rover on the planet Mars.
Exploration
Overall, its exploration history is similar to those of Mars and of Phobos.[34] Deimos has been photographed close-up by several spacecraft whose primary mission has been to photograph Mars, including in March 2023 during a rare close encounter by the Emirates Mars Mission.[35] No landings on Deimos have been made.
In 1997 and 1998, the proposed Aladdin mission was selected as a finalist in the NASA Discovery Program. The plan was to visit both Phobos and Deimos, and launch projectiles at the satellites. The probe would collect the ejecta as it performed a slow flyby (~1 km/s).[36] These samples would be returned to Earth for study three years later.[37][38] The principal investigator was Carle M. Pieters of Brown University. The total mission cost, including launch vehicle and operations was $247.7 million.[39] Ultimately, the mission chosen to fly was MESSENGER, a probe to the planet Mercury.[40]
In 2008, NASA Glenn Research Center began studying a Phobos and Deimos sample-return mission that would use solar electric propulsion. The study gave rise to the "Hall" mission concept, a New Frontiers-class mission currently under further study.[41]
Also, the sample-return mission called Gulliver has been conceptualized and dedicated to Deimos,[42] in which 1 kilogram (2.2 pounds) of material from Deimos would be returned to Earth.[42]
Another concept of sample-return mission from Phobos and Deimos is OSIRIS-REx 2, which would use heritage from the first OSIRIS-REx.[43]
In March 2014, a Discovery class mission was proposed to place an orbiter in Mars orbit by 2021 and study Phobos and Deimos. It is called Phobos And Deimos & Mars Environment (PADME).[44][45]
Human exploration of Deimos could serve as a catalyst for the human exploration of Mars. Recently, it was proposed that the sands of Deimos or Phobos could serve as a valuable material for aerobraking in the colonization of Mars.[46] See Phobos for more detail.
In April 2023, astronomers released close-up global images, for the first time, of Deimos that were taken by the Mars
See also
- List of missions to the moons of Mars
- List of natural satellites
- Moons of Mars – Natural satellites orbiting Mars
- Phobos and Deimos in fiction– Depictions of the planet
- Transit of Deimos from Mars – Transit of a Moon of Mars
Notes
- ^ Given in contemporary sources as "11 August 14:40" Washington Mean Time, using a pre-1925 astronomical convention of beginning a day at noon,[13] so 12 hours must be added to get the actual local mean time.[14][15][16][17]
References
- ^ The Century Dictionary and Cyclopedia (1914)
- ^ "Moons of Mars – the Center for Planetary Science".
- ^ "Deimos". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 22 March 2020.
- ^ Harry Shipman (2013) Humans in Space: 21st Century Frontiers, p. 317
- ^ a b c d e f "HORIZONS Web-Interface". NASA. 21 September 2013. Retrieved 4 December 2013.
- ^ a b c d "Mars: Moons: Deimos". NASA Solar System Exploration. 30 September 2003. Archived from the original on 12 October 2012. Retrieved 2 December 2013.
- ^ PMC 10290967. 103.
- ^ Jacobson (2010), as cited in Ernst et al. (2023).[7]
- ^ a b "Planetary Satellite Physical Parameters". Jet Propulsion Laboratory (Solar System Dynamics). 13 July 2006. Retrieved 29 January 2008.
- ^ "Mars' Moons".
- ^ ISBN 978-3-540-68852-5.
- ^ Staff (2016). "Deimos". SeaSky.org. Retrieved 23 January 2016.
- doi:10.1086/122784.
- ^ Hall, A.; Observations of the Satellites of Mars, Astronomische Nachrichten, Vol. 91, No. 2161 (17 October 1877, signed 21 September 1877) pp. 11/12–13/14
- ^ Morley, T. A.; A Catalogue of Ground-Based Astrometric Observations of the Martian Satellites, 1877–1982, Astronomy and Astrophysics Supplement Series, Vol. 77, No. 2 (February 1989), pp. 209–226 (Table II, p. 220: first observation of Deimos on 1877-08-12.32526)
- ^ Notes: The Satellites of Mars, The Observatory, Vol. 1, No. 6 (20 September 1877), pp. 181–185
- ^ The Discovery of the Satellites of Mars, Monthly Notices of the Royal Astronomical Society, Vol. 38, No. 4, (8 February 1878), pp. 205–209
- ^ Hall, A.; Names of the Satellites of Mars, Astronomische Nachrichten, Vol. 92, No. 2187 (14 March 1878, signed 7 February 1878), p. 47/48
- ^ a b c d Burns, J. A., "Contradictory Clues as to the Origin of the Martian Moons," in Mars, H. H. Kieffer et al., eds., U. Arizona Press, Tucson, 1992
- ^ Landis, G. A., "Origin of Martian Moons from Binary Asteroid Dissociation," American Association for the Advancement of Science Annual Meeting; Boston, MA, 2001; abstract.
- ^ 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
- ^ "Close Inspection for Phobos".
accumulated ejecta from asteroid impacts on the Martian surface
- S2CID 233924981.
- ^ "Moons of Mars – Planetary Sciences, Inc". Retrieved 10 June 2022.
- .
- ^ "Vertical Jump Lab" (PDF). Archived from the original (PDF) on 26 June 2022. Retrieved 18 February 2021.
- ^ "Vertical Jump Velocity Estimation". Google Docs.
- USGSAstrogeology Research Program.
- Planetary Society. Retrieved 19 August 2013.
- ^ a b Richardson, R. S. (December 1943), "If You Were on Mars", Astronomical Society of the Pacific Leaflets, vol. 4, Leaflet No. 178, pp. 214–221
- ^ The Editors of Encyclopaedia Britannica. "Deimos". Encyclopedia Britannica. Retrieved 23 February 2019.
- ^ "Deimos: Facts About the Smaller Martian Moon". Space.com. 8 December 2017.
- ^ Mars Phobos and Deimos Survey (M-PADS)–A Martian Moons Orbiter and Phobos Lander (Ball, Andrew J.; Price, Michael E.; Walker, Roger J.; Dando, Glyn C.; Wells, Nigel S; and Zarnecki, John C. (2009). Mars Phobos and Deimos Survey (M-PADS)–A Martian Moons Orbiter and Phobos Lander. Advances in Space Research, 43(1), pp. 120–127.)
- ^ Crane, Leah. "Amazing images of Mars's moon Deimos snapped by Emirates Mars Mission". New Scientist. Retrieved 25 April 2023.
- S2CID 129101577.
- ^ Pieters, Carle. "ALADDIN: PHOBOS–DEIMOS SAMPLE RETURN" (PDF). 28th Annual Lunar and Planetary Science Conference. Retrieved 28 March 2013.
- ^ "Messenger and Aladdin Missions Selected as NASA Discovery Program Candidates". Archived from the original on 4 April 2017. Retrieved 28 March 2013.
- ^ "Five Discovery mission proposals selected for feasibility studies". Retrieved 28 March 2013.
- ^ "NASA Selects Missions to Mercury and a Comet's Interior as Next Discovery Flights". Retrieved 28 March 2013.
- Bibcode:2010LPI....41.1633L.
- ^ a b "Dr. Britt – The Gulliver Mission: Sample Return from Deimos" (PDF).
- Bibcode:2012LPICo1679.4017E– via NASA ADS.
- ^ Lee, Pascal; Bicay, Michael; Colapre, Anthony; Elphic, Richard (17–21 March 2014). Phobos And Deimos & Mars Environment (PADME): A LADEE-Derived Mission to Explore Mars's Moons and the Martian Orbital Environment (PDF). 45th Lunar and Planetary Science Conference (2014).
- ^ Reyes, Tim (1 October 2014). "Making the Case for a Mission to the Martian Moon Phobos". Universe Today. Retrieved 5 October 2014.
- )
- S2CID 258311112. Retrieved 5 May 2023.
- ^ Howell, Elizabeth (24 April 2023). "This is our 1st detailed look at Mars's most mysterious moon Deimos (photos) - The debate over the moon's origin story is not over yet". Space.com. Retrieved 25 April 2023.
- ^ "EMM unveils new Deimos observations at EGU23, extends mission". Sharjah24. 24 April 2023.