The Heat Flow and Physical Properties Package (HP3) for the InSight Mission

Abstract

The Heat Flow and Physical Properties Package HP 3 for the InSight mission will attempt the first measurement of the planetary heat flow of Mars. The data will be taken at the InSight landing site in Elysium planitia (136 • E, 5 • N) and the uncertainty of the measurement aimed for shall be better than ±5 mW m −2. The package consists of a mechanical hammering device called the "Mole" for penetrating into the regolith, an instrumented tether which the Mole pulls into the ground, a fixed radiometer to determine the surface brightness temperature and an electronic box. The Mole and the tether are housed in a support structure before being deployed. The tether is equipped with 14 platinum resistance temperature sensors to measure temperature differences with a 1-σ uncertainty of 6.5 mK. Depth is determined by a tether length measurement device that monitors the amount of tether extracted from the support structure and a tiltmeter that measures the angle of the Mole axis to the local gravity vector. The Mole includes temperature sensors and heaters to measure the regolith thermal conductivity to better than 3.5% (1-σ) using the Mole as a modified line heat The InSight Mission to Mars II Edited by William B.

Evaluating the Wind-Induced Mechanical Noise on the InSight Seismometers

“…The baseline deployment configuration for SEIS, the wind and thermal shield (WTS) and the Heat Flow and Physical Properties Package (HP3, the second InSight instrument; Spohn et al 2014) is given in Fig. 8.…”

Calibration of the Heat Flow and Physical Properties Package (HP) for the InSight Mars Mission

“…TEM-P consists of 14 PT100 sensors, which are mounted on a Kapton based tether, and associated readout electronics, which measure the PT100 resistance in a four-wire (Kelvin) configuration (see Spohn et al, 2018, for a detailed description of the readout circuit). TEM-P consists of 14 PT100 sensors, which are mounted on a Kapton based tether, and associated readout electronics, which measure the PT100 resistance in a four-wire (Kelvin) configuration (see Spohn et al, 2018, for a detailed description of the readout circuit).…”

“…While this does not fully cover the design range of the HP 3 system (Spohn et al, 2018), which shall measure thermal conductivity down to 0.02 W m −1 K −1 , the availability of certified standard materials is limited by the thermal conductivity of ambient air, which is close to 0.024 W m −1 K −1 under standard temperature and pressure conditions. While this does not fully cover the design range of the HP 3 system (Spohn et al, 2018), which shall measure thermal conductivity down to 0.02 W m −1 K −1 , the availability of certified standard materials is limited by the thermal conductivity of ambient air, which is close to 0.024 W m −1 K −1 under standard temperature and pressure conditions.…”

“…During descent, depth of the sensors will be determined by measuring the attitude of the mole with respect to vertical using static tiltmeters, while simultaneously measuring the amount of paid-out tether. Details of the design of the heat flow probe are given in Spohn et al (2018). Details of the design of the heat flow probe are given in Spohn et al (2018).…”

“…Taken together, the heat flow measurement uncertainty is expected to be better than 5% at a 1-level, but systematic errors caused by the measurement setup close to the InSight lander will likely increase this figure to 10% (Spohn et al, 2018). Calibration and verification of the thermal conductivity Note.…”