Launch is scheduled for February or March of 1999. 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 three 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), one at the equatorial far side, and one near the border of the near and far sides. 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.
The main body of the orbiter is a 120 cm diameter cylinder which is 111 cm in height, excluding the engine nozzle which protrudes from the bottom of the craft. An orbit manuevering system, S-band antenna, and UHF-band antenna are situated on an end of the cylinder, and a reaction control and another S-band antenna on the other end. Three solar arrays extend perpendicular to the cylinder axis, equally spaced around the body. A monochromatic mapping camera with a resolution of 30 m is attached to the side of the cylinder below one of the solar panels. It will be used to take images near the terminator, where the lighting will enhance subtle topographic features. The spacecraft is spin-stabilized. Attitude and spin rate are controlled by an N2H4 monopropellant reaction control system. Orbital manuevering near the Moon is done using a bipropellant (N2O4 and N2H4) engine.
The penetrators are missile-shaped cylinders, 90 cm in length and 14 cm in diameter, and are attached to the sides of the orbiter body between the solar arrays with their long axes oriented in the same direction as the cylinder axis. The penetrators have deorbit rocket engines which are fired after separation. During free fall descent side-jets are used to orient the penetrators. The deorbit motor and attitude controls are jettisoned before impact. Each penetrometer contains a two-component seismometer, a heat flow probe, a tiltmeter, an accelerometer, a radio transmitter and an antenna. The instruments are powered by Li-SOCL2 (super lithium) batteries with an expected lifetime of one year.
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Institute of Space and Aeronautical Science, U of Tokyo/Japan
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