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2011 MD

2011 MD

2011 MD imaged by Spitzer in February 2014
Discovery[1][2]
Discovered by	LINEAR
Discovery site	Lincoln Lab's ETS
Discovery date	2011 June 22 (first observed only)
Designations
MPC designation	2011 MD
Minor planet category	NEO · Apollo[1] · Amor[3]
Orbital characteristics[1]
Epoch 13 July 2011 (JD 2455755.5)
Uncertainty parameter2[1] · 0[3]
Observation arc	2.65 yr (967 days)
Aphelion	1.1031 AU
Perihelion	1.0161 AU
Semi-major axis	1.0596 AU
Eccentricity	0.0411
Orbital period (sidereal)	1.09 yr (398 days)
Mean anomaly	11.051°
Mean motion	0° 54m 13.32s / day
Inclination	2.5624°
Longitude of ascending node	273.96°
Argument of perihelion	4.6748°
Earth MOID	0.0003 AU (0.1 LD)
Physical characteristics
Mean diameter	6 m (estimate)[4][5]
Mean density	1 g/cm3 (est. rubble pile)[4]
Synodic rotation period	0.1937 h[1]
Geometric albedo	0.3[5]
Absolute magnitude (H)	28.0[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]

Description[edit]

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]

Gallery[edit]

Trajectory of 2011 MD projected onto the Earth's orbital plane. Note, from this viewing angle, the asteroid passes underneath the Earth.

See also[edit]

• Asteroid capture
• Asteroid Redirect Mission

References[edit]

External links[edit]

Wikimedia Commons has media related to 2011 MD.

• Encounter animations Archived 27 June 2018 at the Wayback Machine (Pasquale Tricarico)
• 2011 MDatNeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
• 2011 MDatESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• 2011 MD at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters