|Discovery and designation|
|Discovery site||Kitt Peak|
|Discovery date||April 11, 1996|
|Alternative names||1996 GT|
|Epoch JD 2456200.5 (30 September 2012)|
|Semi-major axis||1.644 AU|
|Orbital period||2.108 yr (770.1 d)|
|Longitude of ascending node||73.239°|
|Argument of perihelion||319.236°|
|Dimensions||~800 m (primary)
~150 m (secondary)
|Mean density||1.7±0.4 g/cm3|
|Sidereal rotation period||2.259 h|
|Spectral type||Xk (SMASSII)|
|Absolute magnitude (H)||18.0|
65803 Didymos (1996 GT) is an Apollo asteroid discovered on April 11, 1996 by Spacewatch at Kitt Peak. It has a satellite orbiting it with a period of 11.9 hours, hence the appellation "Didymos", meaning "twin". The primary asteroid is about 800 m in diameter, the satellite is about 150 m in diameter in an orbit about 1.1 km from the primary. The rotation rate of Didymos is fast, 2.26 hours. Its density is 1.7±0.4 g/cm3. Didymos is the most easily reachable asteroid of its size from Earth, requiring a delta-v of only 5.1 km/s for a spacecraft to rendezvous compared to 6.0 km/s to reach the Moon.
Its approach to Earth in November 2003 was especially close with a distance of 7.18 million km; it will not come that near until November 2123, with a distance of 5.9 million km. Didymos also passes very close to Mars: 4.69 million km in 2144.
- JPL Small-Body Database Browser on 65803 Didymos
- "Delta-v for spacecraft rendezvous with all known near-Earth asteroids". 2010. Retrieved 2010-10-07.
- Johnston's Archive of Asteroids with Satellites -(65803) Didymos
- JPL Delta-v for spacecraft rendezvous with all known near-Earth asteroids
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