(385250) 2001 DH47
, provisional designation , is a sub-kilometer asteroid and Mars trojan orbiting 60° behind the orbit of Mars near the . Discovery, orbit and physical properties. was discovered on 1 February 2001 by the Spacewatch program, observing from Steward Observatory, Kitt Peak and classified as Mars-crosser by the Minor Planet Center. Its orbit is characterized by low eccentricity (0.035), moderate inclination (24.4º) and a semi-major axis of 1.52 AU. Its orbit is well determined as it is currently (March 2013) based on 45 observations with a data-arc span of 3,148 days. It has an absolute  magnitude of 19.7 which gives a characteristic diameter of 562 m. Mars trojan and orbital evolution. It was identified as Mars trojan by H. Scholl, F. Marzari and P. Tricarico in 2005 and its dynamical half-lifetime was found to be of the order of the age of the Solar System. Recent calculations confirm that it is indeed a stable Mars trojan with a libration period of 1365 yr and an amplitude of 11°. These values as well as its short-term orbital evolution are very similar to those of 5261 Eureka. Origin. 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 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.