(29075) 1950 DA
 | |
| Discovery | |
|---|---|
| Discovered by | Carl A. Wirtanen |
| Discovery date | February 23, 1950 |
| Designations | |
| 2000 YK66 | |
| Apollo | |
| Orbital characteristics | |
| Epoch March 06, 2006 (JD 2453800.5) | |
| Aphelion | 383.148 Gm (2.561 AU) |
| Perihelion | 125.117 Gm (0.836 AU) |
| 254.133 Gm (1.699 AU) | |
| Eccentricity | 0.508 |
| 808.726 d (2.21626 a) | |
Average orbital speed | 21.30 km/s |
| 75.965° | |
| Inclination | 12.184° |
| 356.802° | |
| 224.503° | |
| Physical characteristics | |
| Dimensions | 1.1–1.4 km |
| Mass | >3,000 x 109 kg |
Mean density | 3.0 + g/cm³ |
| ? m/s² | |
| ? km/s | |
| 0.0884 d (2.1216 h) | |
| Albedo | 0.2-0.25 |
| Temperature | ? K |
Spectral type | E or M |
| 17.0 | |
(29075) 1950 DA is a near Earth asteroid. It is notable for having the highest known probability of impacting Earth (although this probability remains low). For a few days in December 2004 it was temporarily surpassed by 99942 Apophis and in November 2008 the much smaller object 2008 TC3 briefly had a higher probability of impact (TC3 then impacted the Earth).
Discovery and name
1950 DA was first discovered on February 23, 1950 by Carl A. Wirtanen at Lick Observatory. It was observed for seventeen days and then lost until 2000, due to the large uncertainties in Wirtanen's orbital solution.
Observations
In 2001, 1950 DA made a close approach to the Earth coming to within 7.8 million km. It was studied by radar at the Goldstone and Arecibo observatories from March 3 to 7, 2001.
The studies showed that the asteroid has a mean diameter of 1.1–1.4 km. Optical lightcurve analysis by Lenka Sarounova and Petr Pravec shows that its rotation period is 2.1216 ± 0.0001 hours. Due to its short rotation period and high radar albedo, 1950 DA is thought to be fairly dense (more than 3 g/cm³). and likely composed of nickel-iron[1].
Possible Earth impact
If 1950 DA continues on its present orbit, it will approach near to the Earth on March 16, 2880. However, over the intervening time, its rotation will cause its orbit to change (by the Yarkovsky effect). Available radar and optical data suggest two possible pole directions[2]; one trajectory misses the Earth by tens of millions of kilometers, while the other has an impact probability of 1 in 300.
The energy released by a collision with an object the size of 1950 DA would 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.
See also
References
- ^ 1950DA Planning on the NASA website (last accessed on October 7, 2007).
- ^ Asteroid 1950 DA