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TGO in orbit
post Nov 2 2016, 05:18 PM
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The latest and greatest on the plans for the CaSSIS imaging instrument:

After ExoMars TGO has reached its Mars Capture Orbit, the intention is to switch on CaSSIS in the week from November 21 to 28 and acquire images of Mars for the first time. A media release is planned on 1 December 2016 when ESA’s Ministerial Council is being held in Lucerne.


The highly elliptical orbit is not ideal. When we approach Mars, the orbital speed is much higher than in our science orbit and the timing will be difficult to get right. Our aim is to get something – we do our best – and learn from what we get.


When should the image be acquired, do we have enough time to rotate the instrument to get the 2nd half of a stereo pair, do we have enough time to get the data out of the instrument before the next image should be acquired? That planning process costs a lot of time and we don’t have many people to help do it. The hard part in MCO is that the speed over the surface at periapsis is much quicker than in the circular orbit so there is a good chance to mess it up.


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post Apr 19 2020, 08:10 AM
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During the last MEPAG meeting it was said that there has been a recent malfunction of the ACS TIRVIM channel on ExoMars TGO. The cryocooler is no longer able to bring the "IR detector to working temperature". There is no detailed treatment in the presentation materials what this actually means for the further operation of the TIRVIM channel in particular or the science operations in general; besides, that it was mainly used for a general characterization of the martian atmosphere, nor possible root causes of the technical problem are mentioned (A dedicated press release would be desirable). The initial TIRVIM design had two cooled detectors and one redundant pyroelectric detector working at ambient temperature. Because of mass constraints, the design was changed, one of the two cooled detectors and the redundant pyroelectric detector had to be cancelled. That is unfortunate, indeed. The cryocooler is a RICOR K508 Stirling cycle cryogenic refrigerator adapted for operation in space, similar cryocoolers were also used in the ACS MIR channel and NOMAD instrument on ExoMars TGO, as well as highly successfully in many other current and past interplanetary projects.
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