Editing Deimos (moon) (section)

== Origin ==

The origin of Mars' moons is unknown and the hypotheses are controversial.<ref name="burns">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</ref> The main hypotheses are that they formed either by [[asteroid capture|capture]] or by [[accretion (astrophysics)|accretion]].

Because of the postulated similarity to the composition of [[Asteroid spectral types|C- or D-type]] asteroids, one hypothesis is that the moons may be objects captured into Martian orbit from the [[asteroid belt]], with orbits that have been circularized either by [[atmospheric drag]] or [[tidal force]]s,<ref name="cazenave" /> as capture requires dissipation of energy. The current [[Martian atmosphere]] is too thin to capture a Phobos-sized object by [[atmospheric braking]].<ref name="burns" /> [[Geoffrey A. Landis|Geoffrey Landis]] has pointed out that the capture could have occurred if the original body was a [[binary asteroid]] that separated due to tidal forces.<ref name="landis">Landis, G. A., "Origin of Martian Moons from Binary Asteroid Dissociation," American Association for the Advancement of Science Annual Meeting; Boston, MA, 2001; [https://ntrs.nasa.gov/search.jsp?R=946501&id=8&qs=No%3D70%26N%3D4294808501 abstract].</ref> 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 [[planetesimal]].<ref>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</ref><ref>{{cite web |title=Close Inspection for Phobos |url=http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=31031 |quote=accumulated ejecta from asteroid impacts on the Martian surface}}</ref>

In 2021, Amirhossein Bagheri ([[ETH Zurich]]), Amir Khan ([[ETH Zurich]]), [[Michael Efroimsky]] ([[United States Naval Observatory|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 [[InSight|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.<ref>{{Cite journal|last1=Bagheri|first1=Amirhossein|last2=Khan|first2=Amir|last3=Efroimsky|first3=Michael|last4=Kruglyakov|first4=Mikhail|last5=Giardini|first5=Domenico|date=22 February 2021|title=Dynamical evidence for Phobos and Deimos as remnants of a disrupted common progenitor|url=https://www.nature.com/articles/s41550-021-01306-2|journal=Nature Astronomy|volume=5|issue=6|language=en|pages=539–543|doi=10.1038/s41550-021-01306-2|bibcode=2021NatAs...5..539B |s2cid=233924981|issn=2397-3366}}</ref>