SEIS instrument thermal control for the InSight Martian mission – Modeling and first thermal test

Date

2014-07-13

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Publisher

44th International Conference on Environmental Systems

Abstract

The objective of NASA’s mission InSight (INterior exploration using Seismic Investigations, Geodesy and Heat Transport) is to investigate Mars internal structure and meteorite impact flux. The InSight lander will deploy on Mars surface the seismometer SEIS (Seismic Experiment of Interior Structure), provided by CNES (Centre National d’Etudes Spatiales, France). The thermal design of this instrument is driven by the extreme thermal Martian environment, limited power availability and requirements led by scientific performance. Based on these constraints, SEIS thermal control is mainly passive and follows three basic rules: improve insulation, limit heat leaks and maximize thermal inertia. During winter, this passive system is helped by 1.5W heating power. This paper presents its thermal design, its mathematical modeling and thermal tests performed by a STM (Structural and Thermal Model). First of all, a thermal model of the SEIS instrument has been performed using a nodal approach. This model proposes a detailed modeling of the Martian environment and pays particular attention to accurate computation of heat leaks. Then, a complete thermal test has been done on a SEIS STM in CNES facilities, both in vacuum and 7mBar nitrogen conditions (more than 10 phases, 38 days). Steady state and transient data were collected to allow correlation of SEIS thermal model. This model was used to predict SEIS thermal performances. These predictions show that SEIS will be maintained within allowable flight temperatures during flight.

Description

Tucson, Arizona
Ludovic Perrin, Centre National d’Etudes Spatiales, France
Julien Valette, Centre National d’Etudes Spatiales, France
Nicolas Liquiere, Epsilon Ingénierie, France
The 44th International Conference on Environmental Systems was held in Tuscon, Arizona, USA on 13 July 2014 through 17 July 2014.

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