Speaker
Description
EnVision is one of the three candidates for ESA's next medium class mission with the aim to explore the link between geological activity and the Venusian atmosphere. The mission consists of a suite of instruments to probe various layers of the Venus atmosphere, surface and sub-surface.
The topic of this presentation is a preliminary thermal study for the VenSpec-H instrument developed by the Royal Belgian Institute for Space Aeronomy (BIRA). The instrument is a spectrometer which is tasked with mapping the near surface atmosphere with the aim to identify water and sulphur dioxide compounds related to volcanic activity. The instrument consists of a warm section which houses a detector-cooler assembly and a cold section consisting of the optics with a challenging temperature requirement of -60 °C and stability of +/-1 °C.
It became apparently early on that the instrument would have operational constraints whilst trying to achieve a purely passive thermal control design due to the harsh Venus thermal environment. A scan of the mission profile including multiple attitudes was performed to assess the spacecraft sink temperatures and to trade-off the location of a cold and warm section radiator on the spacecraft. There was a requirement on the thermal analyses to go beyond the standard hot/cold case definition in order to demonstrate the instrument feasibility during the Venus year. This was made possible due to some in-house post-processing workflows of the thermal analysis results.
A number of radiator designs were investigated to try to minimise the influence of Venus Albedo and IR planet fluxes, with tilted cavity radiators showing the best performance. This concept was developed to produce a simplified coupled model of the instrument and spacecraft in order to identify any constraints on operation.
Finally, recommendations were given to instrument team which highlighted the critical design parameters to enable the planning of early characterisation tests to reduce the uncertainties. In addition, a recommendation of bi-annual spacecraft flip over manoeuvre to maintain a cold face was adopted by the system team. The study is ongoing with the next milestone being MSR in early 2021.
