Science

Japan having problems launching SELENE orbital Moon mission

by William Atkins

Tuesday, 24 July 2007

The Japanese lunar orbiter SELENE has been delayed again; it is already four years behind schedule.

Science Discussions

The Selenological and Engineering Explorer (SELENE), also called Kaguya, is a lunar orbiter that, once in orbit about 100 kilometers (60 miles) above the Moon, will send two smaller satellites into polar lunar orbits. Its mission is to study the origins and evolution of the Moon, along with researching the Moon’s surface.

(Kaguya comes from the name of a princess in a Japanese story called “The Tale of the Bamboo Cutter”.)

However, after being told that another satellite had its onboard electronic condenser installed improperly, engineers at the Japan Aerospace Exploration Agency (JAXA)—Japan’s space agency that is comparable to the U.S.’s NASA—found that similar components on SELENE’s two smaller satellites had been improperly installed.

The August 16, 2007 launch on board its expendable H-IIA (or, H-2A) launch system has been delayed because of these technical difficulties. Its new launch date will be announced at a later date. The rocket is made by Mitsubishi Heavy Industries and ATK Thiokol.

When it is finally launched, SELENE will be placed in a 281 kilometer (perigee) by 232,800 kilometer (apogee) (175 mile by 144,700 mile) orbit about the Earth. Then, about nineteen days into its flight to the Moon, SELENE will be positioned into a 120 by 13,000 kilometer (75 by 8,000 mile) polar orbit. Following successful completion of its lunar orbit, SELENE will deploy its two satellites. The relay satellite is used to communicate between SELENE and ground controllers on the Earth. The other satellite, what is called a VLBI (very long baseline interferometry) satellite, will be used to measure the position and precession of the Moon.

Besides the two satellites, SELENE will also carry a wide variety of scientific instruments, including a terrain camera, high-definition television (HDTV) camera, x-ray fluorescence spectrometer, gamma ray spectrometer, charged particle spectrometer, upper atmosphere and plasma imager, multi-band imager, laser altimeter, and lunar radar sounder.

SELENE is Japan’s first lunar orbiter. It has a reported cost of $264 million, in U.S. dollars. Once in orbit about the Moon, SELENE will remain there for about one year.

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