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2011 MD

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2011 MD
2011 MD imaged by Spitzer in February 2014
Discovered byLINEAR
Discovery siteLincoln Lab's ETS
Discovery date2011 June 22
(first observed only)
2011 MD
NEO · Apollo[1] · Amor[3]
Orbital characteristics[1]
Epoch 13 July 2011 (JD 2455755.5)
Uncertainty parameter 2[1] · 0[3]
Observation arc2.65 yr (967 days)
Aphelion1.1031 AU
Perihelion1.0161 AU
1.0596 AU
1.09 yr (398 days)
0° 54m 13.32s / day
Earth MOID0.0003 AU (0.1 LD)
Physical characteristics
Mean diameter
m (estimate)[4][5]
Mean density
g/cm3 (est. rubble pile)[4]
0.1937 h[1]

2011 MD is a bright micro-asteroid, classified as near-Earth object of the Apollo and Amor group, respectively.[1][3] On 27 June 2011, at around 17:00 UTC (13:00 EDT), the object passed exceptionally close to Earth's surface at a distance of approximately 12,000 kilometers (7,500 mi), roughly the diameter of the Earth.[6][7][8]


2011 MD on 26 June 2011

Although 2011 MD was initially believed to be space junk, subsequent observations confirmed that it is an asteroid. 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.[7]

2011 MD was discovered on 22 June 2011, by astronomers of the Lincoln Near-Earth Asteroid Research (LINEAR) at the U.S. Lincoln Laboratory Experimental Test Site in Socorro, New Mexico, by a pair of robotic telescopes. According to original rough estimates, the asteroid's length was between 10 and 45 meters (30 and 150 ft).[3][9] However, according to the more recent absolute magnitude (H) measurement of 28.1[1] and its albedo of 0.3, the asteroid is closer to 6 meters or 20 feet in diameter.[5]

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.[9]

The 27 June 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[1] 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.[4] The asteroid is a porous rubble pile with a density similar to water.[4] On 19 June 2014, NASA reported that asteroid 2011 MD was a prime candidate for capture by the Asteroid Redirect Mission (ARM) in the early 2020s.[10]

Parameter Epoch aphelion




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°


Trajectory of 2011 MD projected onto the Earth's orbital plane. Note, from this viewing angle, the asteroid passes underneath the Earth.
Trajectory of 2011 MD from the general direction of the Sun.
Artist's concept of spacious structure of asteroid 2011 MD[11]

See also[edit]


  1. ^ a b c d e f g h i "JPL Small-Body Database Browser: (2011 MD)" (2014-02-12 last obs.). Jet Propulsion Laboratory. Retrieved 7 February 2018.
  2. ^ "MPEC 2011-M23 : 2011 MD". IAU Minor Planet Center. 23 June 2011. Retrieved 5 January 2013. (K11M00D)
  3. ^ a b c d "2011 MD". Minor Planet Center. Retrieved 7 February 2018.
  4. ^ a b c d NASA JPL. "NASA Announces Latest Progress in Hunt for Asteroids". Jet Propulsion Laboratory. Retrieved 19 June 2014.
  5. ^ a b c Mommert, M.; et al. (2014). "Physical properties of near-earth asteroid 2011 MD". Astrophys. J. 789 (1): L22. arXiv:1406.5253. Bibcode:2014ApJ...789L..22M. doi:10.1088/2041-8205/789/1/L22. S2CID 67851874.
  6. ^ Don Yeomans & Paul Chodas (23 June 2011). "Bend it Like Beckham! Small Asteroid to Whip Past Earth on June 27, 2011". NASA/JPL Near-Earth Object Program Office. Archived from the original on 4 July 2011. Retrieved 26 June 2011.
  7. ^ a b Tony Flanders (23 June 2011). "Asteroid To Buzz Earth Monday, June 27th". Sky & Telescope observing blog. Retrieved 27 June 2011.
  8. ^ "Asteroid Just Buzzed Earth—Came Closer Than the Moon". Archived from the original on 28 June 2011.
  9. ^ a b Paul Sutherland (23 June 2011). "Incoming! Another asteroid to skim by". Skymania: Astronomy and space guide. Archived from the original on 1 July 2011. Retrieved 26 June 2011.
  10. ^ Borenstein, Seth (19 June 2014). "Rock that whizzed by Earth may be grabbed by NASA". AP News. Retrieved 20 June 2014.
  11. ^ "The Spacious Structure of Asteroid 2011 MD (Artist's Concept)". NASA Jet Propulsion Laboratory (JPL). Retrieved 13 April 2022.

External links[edit]