LESIA - Observatoire de Paris

SimEnOm thermal vacuum chamber

Friday 21 September 2018

Goals of the facility

SimEnOm (Simulator of the Environment of Omega) has been developed for simulating the thermal vacuum environment of the OMEGA instrument of the MARS’96 mission and the MARS EXPRESS mission in order to calibrate the instrument.

The SimEnOm facility has as a goal to:

  • Simulate and control the space environmental conditions of an instrument in flight, mainly in terms of vacuum and thermal properties;
  • Allow to control the instrument during thermal vacuum

SimEnOm is located in a clean room of class 10000 or ISO 7 with 2 laminar flows of ISO 5. The setup has been conceptualized with the idea to reuse it for other projects, so with a certain degree of flexibility. It has ever since served for testing the following instruments:

  • VIRTIS-H (ROSETTA & VENUS-EXPRESS) : all the models (STM, EQM, FM)
  • CHEMCAM (Curiosity) : STM model
  • VIHI-PE/Simbio-Sys sur BEPI-COLOMBO : all the models (STM, EQM, FM)
  • MEXIC MF-A sur TARANIS : FM model (Octobre 2015)
  • SUPERCAM Mast Unit / MARS2020 : STM model (April-Mai 2016)
  • XGRE / TARANIS : FM model (June-July 2016)
  • RPW / Solar Orbiter : complete calibration with MEB + PAs + SCM + harness regulated independently in T° (November-December 2016)
  • SUPERCAM Mast Unit / MARS2020 : IR calibration of the EQM model (February - March 2018)
  • ExoMars/RLS_ICEU unit : TVAC FM model (August 2018)


Click on the images to enlarge

SimEnOm chamber closed
SimEnOm chamber closed

Photo Jérôme Parisot

VIRTIS-H instrument integrated in the SimEnOm chamber
VIRTIS-H instrument integrated in the SimEnOm chamber

Photo Jérôme Parisot


SimEnOm with RPW instrument - FM of the Solar Orbiter mission
SimEnOm with RPW instrument - FM of the Solar Orbiter mission

Photo Jérôme Parisot - nov. 2016

Integration of SuperCam Mast Unit instrument - EQM in the SimEnOm chamber (...)
Integration of SuperCam Mast Unit instrument - EQM in the SimEnOm chamber (Mars2020 mission)

Photo Sylvain Cnudde


Description of the setup

The setup includes:

  • A vertical cylindrical vacuum chamber build out of 2 almost equally sized parts:
    • The lower part contains the support and the essential of all the flange connections (pumping, cryogenics and electrical cables). It is supported by three pillars that span over a granite optical bench ;
    • The upper part forms a cover that can be moved vertically. It allows the passage of optical beams through a window (CaF2) ;
    • Another window (ZnSe) is dedicated for the use of a thermal camera ;
  • A pump system (primary + secondary) including :
    • A dry primary pump, with a Roots stage, outside of the cleanroom ;
    • A turbomolecular pump mounted to the vacuum chamber
    • A liquid nitrogen reservoir at the exterior of the vacuum chamber which assures the cryogenic pumping
  • A plate at the interior of the chamber founded on a granite optical bench of which the mechanical support is uncoupled from the vacuum chamber by 3 thermal isolated pillars. This system allows to assure a good mechanical stability, for example, when applying external optical stimuli placed on the optical bench ;
  • A control/command system of the pumping and temperature regulations of the thermal sinks.

The steering interface is programmed in LabVIEW. End of 2015 the setup has been renovated and completely automatized.

Technical characteristics


Pressure in the chamber : 10-7 mbar
Temperature range 77K (-196°C) à 373K (100°C)
Cooling system Liquid nitrogen
Number of independent regulated thermal sinks 8
Ø chamber 100 cm
Height chamber 110 cm
Number of temperature probe channels 96
Precision 4-wires PT100 probes 0,1 °C
Date of first use 01/09/1994
Relocation to Technological Space Center (CTS) 11/04/2018