Jonathan Newell takes a look at a new facility built to provide European space programmes with the ability to simulate the extreme temperatures and low pressure environments of solar missions.
Temperature cycling for assessing the reliability of industrial and commercial products pales almost into insignificance when compared to the hostility of an environment characterised by near vacuum and swings of temperatures between 100 and 440 Kelvin – space!
Supporting space programmes
Most of the world’s existing environmental chambers that are big enough and technically advanced enough to simulate such a cosmic environment are located in the USA to support the NASA space missions, but now a new facility has been build at a test centre in Toulouse to support, amongst other things, the European Space Agency and its missions.
Opened recently by Intespace, the “Simles” auxiliary chamber is a thermal vacuum chamber capable of simulating an environment for space systems and subsystems in extreme temperature conditions, operating at a pressure of less than 10-5 millibars and temperatures between 100K and 440K.
At an impressively cavernous 5m in length with a 4.7m diameter, the chamber is capable of accommodating fully assembled space systems and can even test two large satellite antennas at the same time.
Euclid and SolO
The size of the chamber is also sufficient to house the ESA’s Euclid spacecraft, which will require qualification testing before its scheduled launch in 2020. At roughly 4.5m long by 3.1m in diameter, the Euclid vehicle is a platform for the observation of dark matter and dark energy.
The Simles thermal vacuum chamber is also the ideal answer to the qualification requirements of the dramatic Solar Orbiter (SolO) mission. Due for launch in just three years, the Solar Orbiter will make the closest ever observation of the sun from a polar orbit which takes the spacecraft to within the orbital radius of the planet Mercury, subjecting it to harsher environments than can even be adequately simulated on earth.
One of the advantages of the Simles chamber, according to Intespace, is that it is unique within Europe and offers a modular and flexible mode of operation which can accommodate a range of different types of equipment with no specific additional development being required.
The auxiliary chamber also saves time owing to its rapid cycling and is efficient in terms of operating costs. Originally, the chamber was an annex of the original Simles space simulation chamber at the Toulouse test centre containing a pumping system and collimation mirror.
According to Intespace, the idea of reverse engineering this annex into a complete and independent thermal cavity enabled the company to acquire a new facility offering unique capacity in Europe by optimising the potential of the resources already present in the test centre.
Minimal investment was therefore used to create this essential service which will resolve many problems in the process of qualifying space equipment.
Thermal vacuum chamber testing
Thermal vacuum chambers such as the Simles facility in Toulouse are designed to expose complete vehicles, including spacecraft and satellites, as well as subsystems and components to an environment that represents the conditions of space flight.
This involves reaching very low pressures and cycling between thermal extremes. It is important to perform this temperature cycling in a vacuum because the absence of convection due to the vacuum gives the system completely different heat transfer characteristics. Hot spots remain hotter for longer and cold areas don’t heat up so easily so thermal gradients tend to be much steeper resulting in the potential for related failures in structures and components. Stressing in these conditions is required to expose these failure points.