Hiten
From Wikipedia, the free encyclopedia
| Hiten-Hagoromo (Muses-A) | |
 Hiten spacecraft |
|
| Organization | ISAS |
|---|---|
| Mission type | Orbiter |
| Satellite of | Moon |
| Orbital insertion date | 19 March 1990 |
| Orbits | 10 |
| Launch date | 11:46, 24 January 1990 UTC |
| Launch vehicle | Mu-3S-II (no. 5) |
| Mission duration | 3 years, 2 months |
| NSSDC ID | 1990-007A |
| Webpage | Hiten |
| Mass | 197.4 kg |
The Hiten (Japanese: "flying angel"[1]) spacecraft (known before launch as Muses-A), built by the Institute of Space and Astronautical Science of Japan, was launched on January 24, 1990. It was Japan's first lunar probe and the first robotic lunar probe since the Soviet Union's Luna 24 in 1976.[2] Hiten was designed to be an Earth orbiting spacecraft and a relay for another spacecraft to the Moon. The spacecraft entered a circumlunar orbit and released a small orbiter, Hagoromo (named after the feather mantle of a legendary celestial maiden), into lunar orbit. The transmitter on Hagoromo failed, rendering it scientifically useless, and the orbit insertion burn could only be verified optically. Therefore it was not known that Hagoromo entered lunar orbit thereby achieving success for the Japanese lunar mission as planned. Japan wanted to salvage the mission and proposed a plan to get Hiten to leave Earth orbit and achieve lunar orbit. Unfortunately Hiten only had 10% of the required fuel to make it into lunar orbit. It was determined that Hiten could achieve lunar orbit by using a brand new route to the Moon designed by Edward Belbruno. This low energy lunar transfer used Weak Stability Boundary Theory. This, however, would take several months instead of several days.
The primary mission was concluded on March 30, 1991 and the follow-on mission was started. On April 24, 1991 Hiten left Earth orbit and went to the Moon using Belbruno’s route. On October 2, 1991 Hiten reached the Moon at the prescribed distance. After which, it was put into a looping orbit which passed through the L4 and L5 Lagrange points to look for trapped dust particles. No obvious increase was found by the Munich Dust Counter (MDC). After two months in lunar orbit, the spacecraft's orbit was decaying, so the last of Hiten’s fuel was used to crash it into the lunar surface on April 10, 1993.
This mission marked the first use of a low-energy (weak stability boundary) transfer to modify an orbit and the first use of a transfer to the Moon requiring no delta V for capture.[3]
The only scientific instrument on Hiten was the Munich Dust Counter (MDC). The MDC provided data on the dust environment between the earth and the moon until April 10, 1993 when Hiten was intentionally crashed into the lunar surface at between the craters Stevinus and Furnerius. Hiten was the first lunar probe originating from a country other than the United States or the Soviet Union.
