Sunday, December 16, 2012
This week the planet Earth flew by Toutatis (or vice versa, or both) at a distance of just 0.05 AU (7.5 million km), and Goldstone was there to (radar) image it:
Not bad at all. Toutatis has been fairly well known for quite some time now with images such as this one from 1996 by the same observatory:
So this isn't our first closeup of the asteroid. This one is quite massive with a diameter of 4.5×2.4×1.9 km, meaning that even if it hit the planet at the exact opposite side you would still hear the impact at a volume of 50 dB and the air blast would arrive 16 hours later on your side of the planet. At 500 km away one would suffer first-degree burns with an earthquake heavy enough to damage structures, windows would shatter, many trees would be blown down, etc.
But Toutatis won't hit us.
So what is the second flyby? It was China's Chang'e 2 million, which originally was a lunar probe, then was sent to a Lagrange Point, and after that it was decided to try a flyby of the asteroid. Most were not too hopeful that any good flyby images would be produced given that the probe was not designed for such a task with only a few opportunities to image it, but Chang'e 2 came through:
This is exactly the type of area where up-and-coming spacefaring nations should be contributing. Relatively easy and nearby targets that have not been given priority by other nations.
Unmannedspaceflight.com has a thread here on the flyby.