NSSDCA ID: 2004-006C-07
Mission Name: PhilaeThe MUlti-PUrpose Sensor for Surface and Subsurface Science is a set of components designed to perform in-situ measurements of the thermal conductivity/diffusivity, temperature profile, and material properties of the comet's surface and near-surface at the PHILAE landing site. The primary scientific objectives of MUPUS are: to understand the properties and layering of the near-surface matter and their evolution with time as the comet rotates and approaches the Sun; to understand the energy balance at the surface and its variation with time and depth; to understand the mass balance at the surface and its evolution with time; to provide ground truth for thermal mapping from the Orbiter, and to support other instruments on the Philae Lander.
MUPUS consists of several components regulated through common electronics: an anchor accelerometer (ANC-M), an anchor temperature sensor (ANC-T), an infrared mapper (TM), a penetrator and hammer device (PEN-M), a penetrator temperature sensor (PEN-TP), and a penetrator heater (PEN-THC). The anchoring harpoon contains the accelerometer and the temperature sensor. The accelerometer will measure the deceleration of the harpoon as it penetrates the surface. The rate of deceleration and any changes in this rate will give information on the strength of the material and any layering or inhomogeneities. The temperature sensor in the harpoon will measure long-term temperature changes at the depth of the harpoon. The lead for the anchor sensors is N. Komle. The infrared mapper is mounted near the top of the lander and is used to measure the infrared radiation given off by the surface, giving the surface temperature of the comet in the area around the lander. The lead for this experiment is J. Knollenberg.
Additionally, a 37 cm glass fiber tube with a diameter of 1 cm, the penetrator probe, will be deployed by an arm about one meter from the lander and pushed into the ground gradually by a recoil-free hammer. The depth penetrated with each blow of the hammer will give an indication of the strength and layering in the comet. The penetrator thermal probe, designed to measure the temperature field and thermal conductivity of the comet's near-surface material as a function of time and depth, consists of a linear series of 16 toroidal units. These are arranged within the cylindrical penetrator along 32.5 cm of its length. The toroidal units are made of Kapton layers with thin-film metal conductors. Each unit is an independent RTD (Resistance Temperature Dependent) sensor which can also act as a heater. Each sensor element is sampled using a constant current to obtain a temperature measurement. The same element is heated by a constant voltage source. To make temperature measurements during heating for conductivity studies, the heating cycle is interrupted for a few milliseconds. The sensors are sampled with short current pulses of 20 mA. Temperature resolution is better than 0.05 degrees C with a precision of 0.1 degrees C.
Questions and comments about this experiment can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Norbert Komle | Co-Investigator | Institut fuer Weltraumforschung, Austria | nok@bimgs1.kfunigraz.ac.at |
Dr. Jorg Knollenberg | Co-Investigator | knollenberg@kuehrt.ws.ba.dlr.de | |
Dr. Karsten Seiferlin | General Contact | Universitat Munster | seiferi@uni-muenster.de |
Dr. Tilmann Spohn | Principal Investigator | Universitat Munster | spohn@uni-muenster.de |