The Impact of the Hiten Satellite on the Moon
On April 11,1993, the Japanese satellite Hiten was
purposely crashed onto the surface of the moon at the end of its
three year mission. Using the last of the fuel on board, this crash
was directed to the side of the moon facing the earth for easier
observation. Three teams- the JPL-MMNAV, ISAS-GOOD, and ISAS ONS
groups predicted the impact point quite closely. A map of these
predicted sites can be seen here
It is believed that more precise calulations could be made using a
newer planetary ephemeris that incorporates an improved Moon physical
libration model.
An interesting side note to this incident is Dr. David
Allen's observation of the impact area. Using an infared telescope
at Anglo-Australian Observatory, Epping, Austrailia, he took a
series of pictures showing a cloud caused by Hiten's impact. This
cloud had a diamater of approximately 5 km. One of these pictures
can be found here
It is hoped that we may soon recieve pictures of Hiten's
impact area from the Clementine spacecraft. If the artificial
crater caused by Hiten can be captured on film, it will be the first
such crater of known age, caused by an object of known mass,
density, area, and impact velocity. This could provide valuable
data for the analysis of other craters.
Sources:
Uesugi, Kuninori. "Space Odyssey of an Angel- Summary of the
Hiten's three years Mission", American Astronautical
Society Paper 93-292.
Kuninori Uesugi, Takaji Kato, Tsutomu Ichihkawa, Premkumanr R.
Menon, Lonard Efron, Noboru Muranaka, Masafumi Kimura,
Tomoari Hidaka. "Inference of Hiten's Impact Point on the
Moon's Surface".