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2011MD in February 2014
(Spitzer Space Telescope, IRAC). | |
Discovery[1] | |
---|---|
Discovered by | LINEAR (704) |
Discovery date | 2011 June 22 |
Designations | |
Amor NEO[2] | |
Orbital characteristics | |
Epoch 2012-Sep-30 (Uncertainty=2)[2] | |
Observation arc | 2.65 years (last seen 2014) |
Aphelion | 1.095 AU |
Perihelion | 1.017 AU |
1.056 AU | |
Eccentricity | 0.0370 |
396.5 d | |
56.37° | |
Inclination | 2.445° |
271.6° | |
5.838° | |
Physical characteristics | |
Dimensions | ~6 meters (20 ft)[3][4] |
Mean density | ~1 g/cm³ (rubble pile)[3] |
0.1937 h[2] | |
Albedo | 0.3[4] |
28.1[2] | |
2011 MD is an Apollo asteroid that passed relatively close to Earth's surface — at a distance of about 12,000 kilometers (7,500 mi), roughly the diameter of the Earth — at around 17:00 UTC (13:00 EDT) on June 27, 2011.[2][5][6][7] Although the object was initially believed to be space junk, subsequent observations confirmed that it is an asteroid.[6]
A few hours before the asteroid's nearest approach in 2011, it appeared close to the Sun, so observations were possible for only a brief period. Backyard astronomers were able to observe it with telescopes from Australia, southern Africa, and the Americas.[6]
The asteroid was discovered on June 22, 2011, by the Lincoln Near-Earth Asteroid Research (LINEAR) pair of robotic telescopes in New Mexico, and according to original rough estimates, the asteroid's length was between 10 and 45 meters (30 and 150 ft).[8] However, according to the more recent absolute magnitude (H) measurement of 28.1[2] and its albedo of 0.3, the asteroid is closer to 6 meters in diameter.[4]
Emily Baldwin of Astronomy Now said that there was no threat of collision, and should the asteroid enter Earth's atmosphere, it would "mostly burn up in a brilliant fireball, possibly scattering a few meteorites", causing no likely harm to life or property on the ground.[8]
The June 27, 2011 close approach to Earth increased the orbital period of 2011 MD from 380 days to 396 days. During close approach the asteroid passed Earth at a relative speed of 6.7 km/s[2] with a geocentric eccentricity of 1.1.
2011 MD was observed by the Spitzer Space Telescope in February 2014 and estimated to be 6 meters (20 ft) in diameter.[3] The asteroid is a porous rubble pile with a density similar to water.[3] On June 19, 2014, NASA reported that asteroid 2011 MD was a prime candidate for capture by the Asteroid Redirect Mission (ARM) in the early 2020s.[9]
Parameter | Epoch | aphelion (Q) |
perihelion (q) |
Semi-major axis (a) |
eccentricity (e) |
Period (p) |
inclination (i) |
Longitude ascending node (Ω) |
Mean anomaly (M) |
Argument of perihelion (ω) |
---|---|---|---|---|---|---|---|---|---|---|
Units | AU | (days) | (°) | |||||||
Pre-flyby | 2011-Jun-01 | 1.043 | 1.006 | 1.025 | 0.01804 | 379.1 | 2.739° | 97.79° | 269.8° | 244.3° |
Post-flyby | 2011-Aug-01 | 1.097 | 1.016 | 1.056 | 0.03875 | 396.9 | 2.477° | 273.0° | 29.09° | 4.734° |
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