Prelaunch performance evaluation of the cometary experiment MUPUS‐TP

Abstract

[1] This paper discusses test results obtained in both laboratory and terrestrial environment conditions for the ''Multipurpose Sensors for Surface and Sub-Surface Science'' Thermal Probe (MUPUS-TP), which has been developed for the European Space Agency Rosetta cometary rendezvous mission. The probe is intended to provide in situ long-term observations of the thermal evolution of the comet nucleus and will measure a thermal conductivity profile with time in the top 30 cm of the comet nucleus. The basic operating principles of the probe are briefly described, including typical test results gathered in terrestrial snow and soil. The tests in snow provide verification of the probe as a useful tool for monitoring the metamorphism of snow on the Earth. The tests in soil are intended to demonstrate the probe's suitability as an alternative to other methods of energy measurement currently practiced in soil physics research. The tests of the probe in the natural environment of the Earth provide a demonstration of the behavior of the instrument in the presence of complex energy exchange processes before it is used on the comet.

Prediction of soil thermal conductivity based on penetration resistance and water content or air-filled porosity

“…Further developments combining penetrometer probes with TDR and thermal sensors could allow additional improvement of the equations derived in our study. The developments for combined measurements are particularly useful in space missions where not only energy, but also volume and mass of the equipment are limited [21].…”

“…Since the penetration resistance is more easily and cheaply measured than the thermal conductivity, attempts are undertaken to predict the thermal conductivity based on the penetration resistance in combination with other quantities. Research under controlled space conditions indicated a positive relationship between the penetration resistance and thermal conductivity [21,26]. However, according to our knowledge, these relationships were not studied using data of penetration resistance from field measurements.…”

Thermal conductivity measurements of road construction materials in frozen and unfrozen state

“…The concept of MUPUS may also be useful for applications in terrestrial environments. Therefore several probes of a simplified variant named EXTASE 4 have been built in the frame of another project [10,13]. First tests showed that the interpretation of temperature data recorded by the EXTASE probe in terms of thermal conductivity is by no means an easy task.…”

Mupus – A Thermal and Mechanical Properties Probe for the Rosetta Lander Philae

“…In solid ice the increase was 5%, in snow and sand 10-15% and in a Teflon cylinder with a thermal conductivity of 0.25 W/m K about 10%. Additional tests with a model of the MUPUS penetrator in terrestrial soil showed that the penetrator was more sensitive to weak energy fluxes than the commonly used method of heat flux plates (Marczewski et al, 2004). These authors have reported on a series of test experiments with the MUPUS thermal probe.…”

“…The sensitivity of the bare sensors is slightly worse than that of PT100 standard sensors because of the difference in s 1 in Equation (3). The effective resolution of the flight instrument is limited by the performance of the 16 bit AD converter to about 12 meaningful bits, covering about 200 K, which corresponds to about 0.05 K (see also Marczewski et al, 2004). The temperatures are measured by applying a constant current of 20 mA and measuring the voltage drop across the resistors.…”