[meteorite-list] Hayabusa Successfully Captures Asteroid Itokawa's Shape for the First Time

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Sep 6 13:38:59 2005
Message-ID: <200509061737.j86Hbrg23419_at_zagami.jpl.nasa.gov>

http://www.isas.ac.jp/e/snews/2005/0905.shtml

Hayabusa successfully captured Itokawa Shape for the first time in Space
Japan Aerospace Exploration Agency (JAXA)
September 5, 2005

As of September 4th morning of 2005, Hayabusa is at approximately 1,000
km toward 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.

[Images]
Itokawa Images : 9/4 02:36 UTC (left), 9/4 05:12 UTC (right).
(25 arc-minutes x 25 arc-minutes)

The light curve plot below corresponds to the images above. The images
that should be were estimated numerically and those well agree with one
another. Note the following model illustrates the shape model obtained
based on the ground-based observations including radar measurement
performed last year. (Courtesy JPL/NASA)

Lightcurve
Relative Brightness of Itokawa
 
Itokawa Shape
Itokawa Shape predicted for Sept. 4th Imagery. Ref.Ostro, S.
 
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.
Received on Tue 06 Sep 2005 01:37:53 PM PDT