65803 Didymos
| Discovery | |
|---|---|
| Discovered by | Spacewatch |
| Discovery site | Kitt Peak |
| Discovery date | April 11, 1996 |
| Designations | |
| MPC designation | 65803 |
| 1996 GT | |
| Orbital characteristics[1] | |
| Epoch JD 2456200.5 (30 September 2012) | |
| Aphelion | 2.275 AU |
| Perihelion | 1.013 AU |
| 1.644 AU | |
| Eccentricity | 0.384 |
| 2.108 yr (770.1 d) | |
| 82.933° | |
| Inclination | 3.408° |
| 73.239° | |
| 319.236° | |
| Known satellites | 1 |
| Physical characteristics | |
| Dimensions | ~800 m (primary) ~150 m (secondary) |
|
Mean density
|
1.7±0.4 g/cm3 |
|
Sidereal rotation period
|
2.259 h[1] |
| Xk (SMASSII)[1] | |
| 18.0[1] | |
65803 Didymos (1996 GT) is an Apollo asteroid discovered on April 11, 1996 by Joe Montani at Spacewatch at Kitt Peak. It has a moon, whence the appellation "Didymos", meaning "twin". The primary is about 800 m in diameter and the moon 150 m in diameter. The moon is in an orbit about 1.1 km from the primary and with an orbital period of 11.9 hours. Didymos is the most easily reachable asteroid its size from Earth, requiring a delta-v of only 5.1 km/s[2] for a spacecraft to rendezvous, compared to 6.0 km/s to reach the Moon. It is the target of the proposed AIDA spacecraft, an unmanned mission that would test the possibility of changing an asteroid's orbit via impacting its surface.
Contents
Discovery and naming
Didymos was discovered by Joseph L. Montani using the Spacewatch 0.9-m telescope in 1996. The binary nature of the asteroid was discovered by others; suspicions of binarity first arose in Goldstone delay-Doppler echoes, and these were confirmed with an optical light-curve analysis, along with Arecibo radar imaging on November 23, 2003. It has been informally named "Didymoon".[3]
Montani proposed a name to the International Astronomical Union only after the binary nature of the object was discovered: the name "Didymos" is Greek for "twin". The moon has been nicknamed "Didymoon".
Orbital characteristics
Didymos's 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.
The satellite has an orbital period of 11.9 hr.
Physical characteristics
Didymos rotates rapidly, with a period of 2.26 hours. Its density is 1.7±0.4 g/cm3.
Proposed exploration
Didymos is the target of the proposed Asteroid Impact & Deflection Assessment (AIDA) mission, a collaboration between ESA and NASA.[4][5] This will be the first spacecraft to target an asteroid known to have a moon (243 Ida was visited by the Galileo spacecraft but its moon was a surprise). The mission is intended to test whether a spacecraft could successfully deflect an asteroid on a collision course with Earth; it would study Didymos from orbit, while also crashing a smaller spacecraft into Didymoon, in order to study the effect on its orbit.
See also
References
- ↑ 1.0 1.1 1.2 1.3 JPL Small-Body Database Browser on 65803 Didymos
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ "Telescopes focus on target of ESA's asteroid mission" at phys.org (30 June 2015)
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Asteroid Impact & Deflection Assessment (AIDA) study.
