Mars trojan

The L5 group (shown in green) and the L4 group (light blue) of Mars and Jupiter trojan asteroids shown along with the orbits of Jupiter and the inner planets. Mars is shown in red. The outer orbit is that of Jupiter.
Animation of 1999 UJ7 relative to Sun and Mars 1600-2500
   Sun ·   1999 UJ7 ·   Mars
Animation of 2007 NS2 relative to Sun and Mars 1600-2500
   Sun ·   2007 NS2 ·   Mars

The Mars trojans are a group of trojan objects that share the orbit of the planet Mars around the Sun. They can be found around the two Lagrangian points 60° ahead of and behind Mars. The origin of the Mars trojans is not well understood. One theory suggests that they were primordial objects left over from the formation of Mars that were captured in its Lagrangian points as the Solar System was forming. However, spectral studies of the Mars trojans indicate this may not be the case.[1][2] Another explanation involves asteroids chaotically wandering into the Mars Lagrangian points later in the Solar System's formation. This is also questionable considering the short dynamical lifetimes of these objects.[3][4] The spectra of Eureka and two other Mars trojans indicates an olivine-rich composition.[5] Since olivine-rich objects are rare in the asteroid belt it has been suggested that some of the Mars trojans are captured debris from a large orbit-altering impact on Mars when it encountered a planetary embryo.[6][3]

Presently, this group contains 17 asteroids confirmed to be stable Mars trojans by long-term numerical simulations but only nine of them are accepted by the Minor Planet Center.[7][3][4][8][9][10][11]

Due to close orbital similarities, most of the smaller members of the L5 group are hypothesized to be fragments of Eureka that were detached after it was spun up by the YORP effect (Eureka's rotational period is 2.69 h). The L4 trojan 1999 UJ7 has a much longer rotational period of ~50 h, apparently due to a chaotic rotation that prevents YORP spinup.[12] The spectrum of 121514 show a certain resemblance to that of 2023 FW14 and a common origin cannot be discarded.[13] The spectra of 121514 and 2023 FW14 are very different from those of the Eureka asteroid family members.

List of Mars trojans
Designation Cloud Semimajor axis
(AU) 		Perihelion
(AU) 		Eccentricity Inclination
(°) 		(H) Diameter
(m)
5261 Eureka L5 1.52356 1.42477 0.06484 20.2820 16.13 1880±230
(101429) 1998 VF31 L5 1.52429 1.37150 0.10024 31.2987 17.26 1210+890
−350
(121514) 1999 UJ7 L4 1.52455 1.46491 0.03912 16.7493 17.19 2450±490
(311999) 2007 NS2 L5 1.52379 1.44155 0.05397 18.6194 18.18 790+580
−230
(385250) 2001 DH47 L5 1.52385 1.47111 0.03461 24.4006 18.89 570+420
−170
2009 SE L5 1.52451 1.42524 0.06512 20.6263 19.9 360+260
−110
2011 SL25 L5 1.52391 1.34938 0.11453 21.4953 19.5 430+320
−120
2011 SP189 L5 1.52386 1.46247 0.04029 19.8994 20.9 230+160
−70
2011 SC191 L5 1.52390 1.45678 0.04405 18.7451 19.4 450+330
−130
2011 UN63 L5 1.52378 1.42521 0.06469 20.3635 19.7 390+290
−110
2011 UB256 L5 1.52370 1.41550 0.07101 24.3023 19.9 360+260
−110
2016 AA165 L5 1.52299 1.38650 0.08962 18.7202 20.39 290+210
−90
2016 CP31 L5 1.52365 1.43425 0.05867 23.1314 19.4 450+330
−130
2018 EC4 L5 1.52365 1.43138 0.06056 21.8362 20.0 340+250
−100
2018 FC4 L5 1.52388 1.49781 0.01711 22.1466 21.2 200+140
−60
2018 FM29 L5 1.52391 1.45196 0.04722 21.5004 21.11 210+150
−60
2023 FW14 L4 1.52377 1.28284 0.15811 13.27271 21.59 318+493
−199
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  12. ^ Lovett, R. (2017-10-20). "Sun's light touch explains asteroids flying in formation behind Mars". Science. doi:10.1126/science.aar2794.
  13. ^ Cite error: The named reference spectrum2023FW14 was invoked but never defined (see the help page).