2 August 2013

MERTIS (Mercury Thermal Infrared Spectrometer and Radiometer) is part of the payload of ESA’s BepiColombo mission to Mercury. The MERTIS team is led by the PI H. Hiesinger (Uni Münster) and Co-PI J. Helbert (DLR-PF) and the project management is done by DLR-OS. Our department is involved in this project by the development of the radiometer part of the instrument.

The main scientific goals of the MERTIS radiometer designated as MERTIS-RAD in the following) are:

a) Measurement of the surface temperature of Mercury over the full range of relevant temperatures between 100 K and 700 K
b) Derivation of a thermal inertia map of the planet with a spatial resolution of  2-5 km
c) Determination of roughness parameters of the surface of Mercury.

 MERTIS Radiometer detector unit with MRAD Chip in the center
zum Bild MERTIS Radiometer detector unit with MRAD Chip in the center

The basic concept of the proposed MERTIS radiometer channel is to place a 2x15 elements thermopile double line array sensor chip with integrated optical slit for the spectrometer at the focal plane of the MERTIS TMA entrance optics. One of the line arrays is covered by an on-chip filter with a passband of 8-14 µm whereas the other array is operating very broadband with a passband defined by the MERTIS 7-40 µm entrance filter. The detector chip is a customized design manufactured by IPHT Jena according to the specification of DLR. The small signal voltages of the order of µV to mV generated by the thermopile sensors are transmitted differentially via a starr-flex interface PCB to a proximity electronics, where the signals are multiplexed, amplified, converted to digital units and transmitted to the MERTIS controller.

End of July 2013 the calibration of the MERTIS FM was finished and the instrument was ready for delivery to ESA.

More information from the web pages of DLR-OS and the University of Münster.

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