Phases 0 and A studies for the Lunar Exploration Orbiter (LEO) program have been initiated by the German Aerospace Center in order to broaden the knowledge of the moon's surface and immediate space environment. The overall mission concept established during the study phases consisted of a main spacecraft, accommodating optical, radar and infra-red moon observation instruments and providing passage from earth to the final moon orbit for two twin spacecraft.
After separation from the mother spacecraft the two twin satellites span a constellation on a near polar, low altitude moon orbit optimized for their specific mission purpose.
As part of the overall mission SpaceTech signed responsible for the design of the twin spacecraft as well as the coordination and accommodation of the three related scientific payloads
- the Lunar Precise Range and Range Rate (PRARE-L) instrument for the recovery of the gravity field via continuous Ka-band ranging based measurement of the relative distance between the two satellites
- the Lunar Magnetometer (LunarMag) with a set of two locally separated magnetometers in a quiet spot at the end of a deployed boom on each spacecraft providing for excellent magnetic measurements with unprecedented spatial and temporal resolution
- the Radiation Pressure Sensor (RaPS) measuring the remnant radiation induced forces acting on the spacecraft in the low lunar orbit
Special emphasis in the design of the spacecraft platform has been laid on the feasibility of a one year active measurement life time in the harsh space environment in the low (50 km) lunar near-polar orbit, a mechanically quiet environment for the Ka-band ranging system as well as a magnetically quiet environment for the magnetometers.