The European Space Agency (ESA) has announced that a ground penetrating radar antenna for the ExoMars 2020 rover is being pre-cleaned in an ultra-clean environment in preparation for its sterilisation. The cleaning process aims to prevent terrestrial microbes coming along for the ride to the red planet.
The process is taken place at the Life, Physical Sciences and Life Support Laboratory. Located at ESA's technical centre in the Netherlands, this 35 sq m ISO 1 cleanroom is one of the cleanest places in Europe.
The ultra-clean facility is equipped with a dry heat steriliser used to reduce the microbial ‘bioburden’ on equipment destined for alien worlds.
The chamber’s cleanliness is such that it contains less than 10 particles smaller than a thousandth of a millimetre per cubic metre. A comparable sample of the outside air could well contain millions.
Ultra clean
By international planetary protection agreement, space agencies are legally required to prevent terrestrial microbes hitchhiking to other planets and moons in our Solar System where past or present alien life is a possibility.
Explaining the cleaning process, ESA technician, Alan Dowson, says: “After pre-cleaning and then the taking of sample swabs, the antenna was placed into our dry heat steriliser, to target the required 99.9% bioburden reduction to meet ExoMars 2020’s cleanliness requirements.
To check the effectiveness of this process, the swabs are subjected to a comparable heat shock and then cultivated for 72 hours, to analyse the number of spores and bacteria able to survive.
Dowson continued: "The viable bioburden is then calculated for the surface area of the WISDOM antenna. If this level is below the mission’s maximum then it is cleared for delivery.”
All the cleanroom’s air passes through a two-stage filter system. Anyone entering the chamber has to gown up in a much more rigorous way than a hospital surgeon, before passing through an air shower to remove any remaining contaminants.
The item seen here is the WISDOM (Water Ice Subsurface Deposit Observation on Mars) radar antenna flight model, designed to sound the subsurface of Mars for water ice.
The 2020 mission of the ExoMars programme will deliver a European rover and a Russian surface platform to the surface of Mars. A Proton rocket will be used to launch the mission, which will arrive to Mars after a nine-month journey. The ExoMars rover will travel across the Martian surface to search for signs of life. It will collect samples with a drill and analyse them with next-generation instruments. ExoMars will be the first mission to combine the capability to move across the surface and to study Mars at depth.
