Mars Sample Return

A typical sterilisation process for a lander
A typical sterilisation process for a lander

This complex Flagship mission calls for five spacecraft: an Earth/Mars transfer stage, a Mars orbiter, a descent module, an ascent module and an Earth re-entry vehicle. When the orbiter is in low-altitude orbit around Mars the descent module will be released and descend to the surface of Mars. On board the landing platform of the descent module will be a device to collect samples and an ascent vehicle.

Once samples of Martian soil have been collected they will be loaded on to the Mars ascent vehicle. This will then be launched into orbit around the planet to rendezvous with the Earth re-entry vehicle. After the rendezvous has taken place the Earth re-entry vehicle will return to Earth on a ballistic trajectory with the precious samples. These will then be recovered and isolated in a ‘curation’ facility to prevent contamination of the samples and to allow scientists to analyse them in safety.

An inflatable braking device will probably be used for the descent through the Martian atmosphere, similar to that proposed for the ExoMars mission. For re-entry into the Earth’s atmosphere a parachute or inflatable device system is envisaged.

MSR ascent module
Artist's view of the Mars Sample Return ascent module lifting off from Mars

A number of new technologies will be required to carry out this pioneering mission. These include the landing system on Mars, the Mars ascent vehicle, the rendezvous system in Mars orbit and the Earth re-entry vehicle or capsule. In principle all of these can be tested in a near-Earth environment except for the final qualification of the rendezvous and docking system, which should preferably be carried out in a Mars orbit. The technology required for this Flagship mission will be developed during a series of technology-driven arrow missions.

Some important factors influencing the design and development of the mission are:

  • Landing site This may remain open for some time until knowledge of the Martian geochemical, biological and environmtnal characteristics progressively improve, through previous missions to the planet. This means that the spacecraft design will have to be sufficiently robust to cope with a variety of different landing sites that will be selected at a later stage of the programme.

  • Sample size A soil sample of 500 grammes is being considered in line with the recommendations of the International Mars Exploration Working Group (IMEWG).

  • Sample collection A miniature drill will be needed to collect samples of Martian soil at a certain depth. Samples will be taken from underneath the upper layer of soil as this is expected to be completely sterile due to the high level of radiation. The level will be high because unlike the Earth’s atmosphere, that on Mars does not filter radiation. Signs of past forms of life will probably not be found on the surface due to the high oxidisation levels, which destroy identifiable bio-signatures.

  • Sample protection Careful measures will be needed to protect the sample. On the one hand it will be necessary to avoid contamination of Mars by organisms from Earth and on the other, it will be essential to ensure that no Martian organism – if any exist – contaminates the Earth.

If all goes according to plan, this challenging and complex mission could be launched in the timeframe 2020-2022.

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