2011 SC191

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2011 SC191
Discovered by Mt. Lemmon Survey
Discovery date October 31, 2011
MPC designation 2011 SC191
Martian L5 Martian L5
Orbital characteristics[1]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 0
Observation arc 4715 days (12.91 yr)
Aphelion 1.5910690 AU (238.02053 Gm)
Perihelion 1.4565161 AU (217.89171 Gm)
1.5237925 AU (227.95611 Gm)
Eccentricity 0.0441507
1.88 yr (687.05 d)
0° 31m 26.331s /day
Inclination 18.74554°
Earth MOID 0.459583 AU (68.7526 Gm)
Jupiter MOID 3.37018 AU (504.172 Gm)
Physical characteristics
Dimensions 600 m
0.5-0.05 (assumed)

2011 SC191, also written as 2011 SC191, is a small asteroid orbiting near the L5 point of Mars (60 degrees behind Mars on its orbit).[2][3]

Discovery, orbit and physical properties[edit]

2011 SC191 was first observed on March 21, 2003 by the Near-Earth Asteroid Tracking (NEAT) project at Palomar Observatory using the Samuel Oschin telescope and given the provisional designation 2003 GX20. The object was subsequently lost and re-discovered on October 31, 2011 by the Mt. Lemmon Survey.[4][5] Its orbit is characterized by low eccentricity (0.044), moderate inclination (18.7°) and a semi-major axis of 1.52 AU.[5] Upon discovery, it was classified as Mars-crosser by the Minor Planet Center. Its orbit is well determined as it is currently (March 2013) based on 45 observations with a data-arc span of 3,146 days.[1] 2011 SC191 has an absolute magnitude of 19.3 which gives a characteristic diameter of 600 m.[1]

Mars trojan and orbital evolution[edit]

Recent calculations indicate that it is a stable L5 Mars trojan with a libration period of 1300 yr and an amplitude of 18°.[2][3] These values as well as its short-term orbital evolution are similar to those of 5261 Eureka. Its eccentricity oscillates mainly due to secular resonances with the Earth and the oscillation in inclination is likely driven by secular resonances with Jupiter.[2]


Long-term numerical integrations show that its orbit is very stable on Gyr time-scales (1 Gyr = 1 billion years). As in the case of Eureka, calculations in both directions of time (4.5 Gyr into the past and 4.5 Gyr into the future) indicate that 2011 SC191 may be a primordial object, perhaps a survivor of the planetesimal population that formed in the terrestrial planets region early in the history of the Solar System.[2]

See also[edit]


  1. ^ a b c "JPL Small-Body Database Browser: (2011 SC191)". Jet Propulsion Laboratory. Retrieved 31 March 2016. 
  2. ^ a b c d de la Fuente Marcos, C.; de la Fuente Marcos, R. (April 2013). "Three new stable L5 Mars Trojans". Monthly Notices of the Royal Astronomical Society: Letters. 432 (1): L31–L35. arXiv:1303.0124Freely accessible. Bibcode:2013MNRAS.432L..31D. doi:10.1093/mnrasl/slt028. 
  3. ^ a b Christou, A. A. (2013). "Orbital clustering of Martian Trojans: An asteroid family in the inner solar system?". Icarus. 224 (1): 144–153. arXiv:1303.0420Freely accessible. Bibcode:2013Icar..224..144C. doi:10.1016/j.icarus.2013.02.013. 
  4. ^ Discovery MPEC
  5. ^ a b MPC data on 2011 SC191
Further reading
  • 2011 SC191 Pettarin, E., Vivona, M., McMillan, R. S., Pietschnig, M., Klein, M., Boattini, A., Gibbs, A. R., Ahern, J. D., Beshore, E. C., Garradd, G. J., Grauer, A. D., Hill, R. E., Kowalski, R. A., Larson, S. M., McNaught, R. H., Birtwhistle, P. 2011, Minor Planet Electronic Circular, 2011-T02.
  • Three new stable L5 Mars Trojans de la Fuente Marcos, C., de la Fuente Marcos, R. 2013, Monthly Notices of the Royal Astronomical Society: Letters, Vol. 432, Issue 1, pp. 31–35.
  • Orbital clustering of Martian Trojans: An asteroid family in the inner solar system? Christou, A. A. 2013, Icarus, Vol. 224, Issue 1, pp. 144–153.

External links[edit]