Current Status of Hayabusa and Events Scheduled in November

Hayabusa that arrived at the target asteroid Itokawa on September 12th of this year has performed detailed scientific observation so far by varying its relative position around Itokawa.

As already reported, Hayabusa carried two reaction wheels were lost on July 31st and October 3rd, and its attitude has been maintained by a single wheel together with the chemical engines aboard, while the spacecraft has been operated normally.

In order that the flight can be carried out and completed until the return to the Earth, the fuel consumption required for stabilizing the attitude has to be reduced, and a strenuous effort has been poured to devise the strategy including a number of firing tests in vacuum on the ground. A new control scheme making the firing impulse enough small has now been developed assuring the attitude control resolution to be well managed. This assures the fuel amount required is adequate within that remains. The on-orbit function test was already conducted and it was verified functioning by the actual flight hardware and software aboard. The Hayabusa project team concluded the flight operation until the return to the Earth is feasibly performed, as long as the existing instruments and hardware aboard continue working normally as they are.

The proximity operation assumed in November next month consists of one Rehearsal Descent plus two Touching-downs for sampling. They are scheduled as follows:

1. Rehearsal Descent November 4th,
2. 1st Touching-down for sampling November 12th,
3. 2nd Touching-down for sampling November 25th.

These events will occur around noon in Japan Standard Time in the midst of the operation period from Japan. There are several Rehearsal and Touching-down sites candidates and the events instances may be shifted earlier or later by 6 hours at maximum, depending on the operation status. The concrete schedule will be released as soon as they are determined.

October 27, 2005