Big News for Hayabusa: It wasn't hovering, it landed!!
Posted by Emily Lakdawalla
23-11-2005 7:21 CST
Remember how Hayabusa was virtually still for 30 minutes? JAXA is now saying that Hayabusa actually touched down -- and more than that, they may even have a sample. This is all according to 5thstar's translation of journalist Shin-ya Matsuura's weblog. A quote:
JAXA/ISAS analyzed the date downloaded from the spacecraft. Hayabusa detected an obstacle just below the altitude 17m, when it changed the orientation of the spacecraft towards the surface of Itokawa. At that point the high gain antenna moved away from Earth and the real time communication was lost.
Software onboard Hayabusa tried to go into the emergency take off but the orientation of the spacecraft was too steep (to what?) so it did not take off. It continued the free fall descent and bounded twice on the surface, according to the LRF data and the attitude data. Because the obstacle sensor had been triggered, the sampler horn was not engaged, so the impacter was not deployed. The event happened during the switch over from NASA Goldstone station to Usuda station, so they did not confirm the landing from the Doppler data.
The spacecraft was seemingly at rest with the sampler horn and an edge of the body or a solar panel wing attached to the surface.
The first touch down occurred around 6:10. The second touch down was around 6:30 after a bounce. Another small bounce brought the spacecraft into rest, according to the LRF data.
It stayed on the surface for 30 minutes, all the while it was being heated up by thermal radiation from the surface of Itokawa. Take off was performed by a command from Earth at 6:58, then entered into the safe mode.
And furthermore, in another of Shin-ya Matsuura's weblog entries:
It seemingly landed just like a dog sits down. No leaning to sideways.
Some sand should come up at the impact of the touch down. Part of them should have reached to the sampler capsule. The capsule was programmed to be closed according to the sequence of the touch down, so it is still open now. Scientists insist on closing the capsule, so they will send the closing command in the next communication window tomorrow. There are several capsules on board for two scheduled touch down operations.
Currently Hayabusa is approaching to Itokawa at 4 km per hour. As it closes up, it slows down for delicate positioning. It depends on whether they can bring it back to the starting position, and also on the stamina of the operation team members, to have the second attempt on the 25th.
Again, THANK YOU TO 5THSTAR AND SHIN-YA MATSUURA for your the original reporting and English translations! Without you both I'd have no hope of understanding what was going on with this mission!
For further reading, there is a JAXA release in Japanese (here's the Google translation) about the landing.
For more further reading, check The Planetary Society of Japan's website, on public responses to the landing of the sample capsule.