(29075) 1950 DA

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| category=Apollo
| epoch=March 06, 2006 (JD 2453800.5)
| semimajor=254.133 Gm (1.699 AU)
| perihelion=125.117 Gm (0.836 AU)
| aphelion=383.148 Gm (2.561 AU)
| eccentricity=0.508
| period=808.726 d (2.21626 a)
| inclination=12.184°
| asc_node=356.802°
| arg_peri=224.503°
| mean_anomaly=75.965°
| speed=21.30 km/s
| dimensions=1.1–1.4 km
| mass=? kg
| density=3.0 + g/cm³
| gravity=? m/s²
| escape_velocity=? km/s
| rotation=0.0884 d (2.1216 h)
| spectral_class=?
| abs_mag=17.0
| albedo=?
| temperature=? K}}

Image:1950da color 150.jpg

(29075) 1950 DA is an asteroid considered to be the near Earth object with the highest known probability of impacting Earth, according to the Palermo Technical Impact Hazard Scale. However, for a few days in December 2004 it was temporarily surpassed by 99942 Apophis (which at the time was named only by its provisional designation Template:Mp).

1950 DA, a Mars-crossing asteroid, was first discovered on February 23, 1950 by Carl A. Wirtanen at Lick Observatory; it was observed for 17 days, before being lost for half a century. An object discovered on December 31, 2000 (provisionally designated Template:Mp) was recognized as being the long-lost 1950 DA.

It has been given the number 29075, but does not have a name.

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General information

Radar observations at the Goldstone and Arecibo Observatory from March 3 to 7, 2001 during the asteroid's 7.8 million km approach to the Earth give a mean diameter of 1.1 – 1.4 km. Optical lightcurves by Petr Pravec show that the asteroid rotates every 2.1216 hours.

Due to its relatively fast spin, 1950 DA is thought to be fairly dense (more than 3.0 g/cm³).

If 1950 DA continues on its present orbit, it will approach near to the Earth on March 16, 2880. Over the intervening time, the rotation of the asteroid will cause its orbit to change (by the Yarkovsky effect). A preliminary analysis shows two possible pole directions (Giorgini, et al., 2002 "Asteroid 1950 DA's 2880 Encounter with Earth"). One trajectory will miss the Earth by tens of millions of kilometers, while the other has an impact probability of ¹⁄₃₀₀. The radar observations are currently being reanalyzed, in combination with the optical lightcurves.

The energy released by a collision with 1950 DA could cause major effects on the climate and biosphere which would be devastating to human civilization.

The discovery of the potential impact has heightened interest in asteroid deflection strategies.

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