Development of the heat flow measurement system by the LUNAR-A penetrators

Lunar heat flow experiment is planned by using two LUNAR-A penetrators which will be deployed on the near-side and far-side of the lunar surface in 2000. Each penetrator has seven absolute and eleven relative temperature sensors. Impact experiments for real-size penetrator models onto a lunar-regolith analogue target confirmed that the sensors and electronics used in the Lunar-A Heat Flow Experiment can survive the shock loading expected during penetration of the penetrator in a lunar regolith. The calibration experiment demonstrates that the temperature sensors have a resolution of 0.01 degrees and that the thermal conductivity device have 10 % accuracy. In order to determine the heat flow value, we need a good thermal model and numerical simulation for the penetrator and the regolith which in turn requires accurate measurements of thermal properties of the penetrator's components. The current numerical models indicate that we will be able to obtain the lunar heat flow values within 20 to 30 percents in precision with this method.