ESA’s forest satellite robust for launch
Over the last few months, ESA’s Earth Explorer Biomass satellite has been going through a punishing series of tests to make sure that it will survive the unavoidable blasts of noise and shuddering during liftoff. Engineers have now also tested that it will unfold its solar wing in the correct sequence. Coming through all of this with flying colours, Biomass is a few steps closer to its mission in orbit: to deliver completely new information on our precious forests and the carbon they store.
After being shipped from the UK, last November, the satellite took up residency at Airbus’ Astrolabe facilities in Toulouse, France, for what satellite engineers call ‘the environment campaign’. It is the mechanical part of the campaign that has been completed.
During these mechanical tests, the Biomass satellite was subjected to environments that simulated the noise and vibrations of launch. This is to ensure that it will remain intact and healthy during its rough ride into orbit.
Along with the experienced team of Airbus engineers from the UK, satellite experts from ESA closely followed the tests. The vibration tests were first up followed by the acoustic environment tests in the LEAF chamber.
Stefan Kiryenko, ESA’s Biomass mission lead mechanical engineer, was in Toulouse for the test campaign, “With the completion of the vibration testing, we have verified the compatibility of the satellite with the rocket’s environment. We demonstrated comfortable margins for all of the satellite’s sub-systems.
“In particular, Biomass’ large deployable reflector was under scrutiny, and I am happy to say that it behaved as it should. Congratulations to all team members involved!”
The Biomass satellite’s reflector is a whopping 12 m across and is key to how it will deliver completely new information on forest height and forest biomass. This not only includes the tree trunk but also the bark and branches.
The big umbrella-like part of the satellite reflects the satellite’s P-band radar signal, which passes through the forest. The antenna then receives the backscattered signal, which carries information about the forest structure and can be used to infer parameters such as forest biomass and forest height.
Measurements of forest biomass can be used as a proxy for stored carbon, which will reduce the major uncertainties in calculations of carbon stocks and fluxes on land, including carbon fluxes associated with land-use change, forest degradation and forest regrowth.
Janice Patterson, ESA’s Biomass system engineering and satellite manager, added, “We are all very happy with the outcomes of this test, all the success criteria were achieved, and the satellite behaved in line with expectations. With this we are one step closer to the launch; from a mechanical point of view Biomass is ready to go!”
Following these tests, engineers at Airbus carried out the tricky solar array deployment test – tricky because this is done in the cleanroom where gravity prevails and so this means that the test needs a rather complicated setup; of course, when it happens for real after the satellite has been injected into orbit, it will be free of gravity.
The solar array is a single wing comprising four panels. The panels open from the side of the satellite via a yoke, and once fully deployed the four panels rotate to a fixed angle. Outstretched, the wing has an area of just over five square metres and generates the power that the satellite needs.
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Stay tuned for the next steps of the environmental campaign that will include the tests for the harsh environment of space that place the satellite under the extreme temperature variations it will experience in space.
Biomass is planned to be launched in 2024 from Europe’s Spaceport in Kourou, French Guiana, on a Vega rocket.
