As of September 4th morning of 2005, Hayabusa is at approximately 1,000 km
Earth with respect to Itokawa, a near Earth asteroid target of the
spacecraft, with the
approach speed of 10 km per hour. Hayabusa took a series
of its Optical Navigation
Camera aboard on the day and the photos revealed, for
the first time in space, the
shape information of Itokawa. Left one was taken
when the brightness was at the top,
while the right one was at the bottom.
The upward direction here is almost identical
to the north of the ecliptic frame.
The photos actually taken this time supports the model built before launch and
also shows the rotation axis is almost perpendicular to the ecliptic plane.
This spin axis information also agrees with what was predicted before launch.
It is not legible enough but the tip-to-tip length in left photo looks several
hundred meters long. The rotation period was estimated about 12 hours before
launch, and it well accounts for the observation.
Ostro,S.J., Benner L.A.M., Nolan M.C., Magri C., Giorgini J.D., Scheeres D.
J., Broschart S.B., Kaasalainen M., Vokrouhlicky' D., Chesley S.R., Margot
J.L., Jurgens R.F., Rose R., Yeomans D.K., Suzuki S., and De Jong E.M.
(2004) Radar observations of asteroid 25143 Itokawa (1998 SF36).
Meteoritics & Planetary Science 39:407-424.