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Lunar A

Lunar A [ISAS]

The scientific objectives of the Lunar-A mission to the Moon are to image the surface of the Moon, to monitor moonquakes, measure the near-surface thermal properties and heat flux, and to study the lunar core and interior structure. To achieve these objectives, Lunar-A will carry a mapping camera and two surface penetrators. The surface penetrators are equipped with seismometers and devices to measure heat flow. The seismometers will monitor moonquake activity over the course of a year and this information will be used to learn about the structure of the Moon's interior and the size of the core. The heat flow measurements will provide information on the thermal state and evolution of the Moon.

After launch, Lunar A will go into Earth parking orbit. The spacecraft will then be injected into an orbit around the Earth and Moon. After four and a half of these orbits, Lunar-A will swing out into a wide single orbit with an apogee of 1,185,000 km. At the end of this orbit the spacecraft will re-encounter the Moon and be inserted into lunar orbit. This orbit will have an inclination of 30 degrees and bring Lunar-A within 40 km of the Moon's surface. The spacecraft will deploy two 13 kg penetrators over the course of a month. They will be individually released and impact the Moon at 250 to 300 m/s, burrowing 1 to 3 meters into the surface. One penetrator will be targeted at the equatorial area of the near side (in the vicinity of the Apollo 12 and 14 landing sites) and one at the equatorial far side. After deploying the penetrators, the orbiter will move up to a 200 to 300 km near circular mapping orbit. Data will be stored in memory in the penetrators and transmitted to the orbiter when it transits over each penetrator every 15 days.

Originally planned for a 1995 M-5 [KM-V1] launch, Lunar-A was delayed fom several years, but due to the end of the M-5 program in 2006 no other launch vehicle has been selected. In early 2007 JAXA recommended to cancel the Lunar-A probe, as the development of the penetrator probes has taken so long that the mission's mother ship, which was built 10 years ago, has fallen into disrepair and would require too much money to fix.

The penetrators developed for Lunar-A will be flown on the russian Luna-Glob mission.

Nation: Japan
Type / Application: Lunar orbiter with two penetrators
Operator: ISAS
Propulsion: IHI BT-4
Power: 4 deployable fixed solar arrays, batteries
Mass: 520 kg
Orbit: lunar orbit (planned)
Satellite COSPAR Date LS Launch Vehicle Remarks
Lunar A - cancelled