Japanese satellite begins orbiting moon.

Japanese satellite begins orbiting moon

A Japanese legend tells of Hagoromo, a robe that transported a beautiful princess from the moon to Earth and back. Hagoromo means "feather garment," and it is also the name newly given to a Japanese spacecraft that entered lunar orbit on March 19, making Japan the third nation to reach the moon.

The lunar orbiter was deployed from another craft, called Hiten, launched from Earth on Jan. 24 (SN:3/3/90, p. 138). Their separation occurred less than 1 second from the scheduled time, when Hiten was 16,422.4 kilometers from the moon -- only 2.2 km from the distance planned by officials at Japan's Institute of Space and Aeronautical Sciences (ISAS).

Hagoromo carries no scientific instruments, although it has a camera that photographed both the moon and Earth around the time of deployment, deliberately overexposing the pictures to make each "limb," or edge, clearly visible as a navigational aid for positioning the two craft. Hiten, meanwhile, remains in an Earth-circling orbit.

Hiten also bears the mission's only scientific instrument, a detector to count tiny meteoroids. It had already counted several within a day of Hagoromo's release, says ISAS Director-General Jun Nishimura, who adds that the data are now being calibrated to indicate each micrometeoroid's mass and velocity.

Shortly after Hagoromo's deployment, ground controllers changed Hiten's orbit from an ellipse varying between 442,000 and 727,000 km from Earth to a smaller, more eliptical one varying between 11,000 and 116,000 km. Nishimura says the orbit change is essentially a practice run for a similar maneuver with a Japanese satellite called Geotail. Scheduled for launch in 1992, Geotail is a NASA/ISAS cooperative project to study the tail region of Earth's magnetic field.