Design and analysis of the feet and it's configuration used for the Heat Flow Property Package Instrument (HP3) on-board the Mars Mission InSight

Abstract

The HP3 instrument measures the thermal flux through the Martian crust using a penetration probe. Launched on the InSight mission in 2018, HP3 was deployed for penetration activities in the beginning of 2019. This paper shortly introduces the HP3 instrument and shows the design and analysis process of the feet pattern and of each foot. The pattern of the feet is driven by the accommodation of the instrument on the lander and the need to ensure stability of the instrument on the surface. A four-feet design was chosen as it can be fitted very good into the available volume. During operation, the instrument is vulnerable to tipping as the landing site can be tilted and partially covered with rocks and depressions. Therefore it is shown analytically, that the instrument is stable, although it might be partially located on rocks or depression in combination with a tilted landing site. The new design of the feet is introduced and compared to a flatplate foot. The capability of each design to produce slippage resistance is estimated analytically. The analytical estimations show, that the chosen flight-design generates more slippage resistance than the flat-plate approach. Even though the analytical estimations do not cover all effects generating slippage resistance.