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Radiation risk for Mars astronauts

Data from the ESA-Roscosmos ExoMars Trace Gas Orbiter being presented at the European Planetary Science Congress, EPSC, in Berlin, Germany, this week

Astronauts on a mission to Mars would be exposed to at least 60% of the total radiation dose limit recommended for their career during the journey itself to and from the Red Planet, according to data from the ESA-Roscosmos ExoMars Trace Gas Orbiter being presented at the European Planetary Science Congress, EPSC, in Berlin, Germany, this week.


The orbiter’s camera team are also presenting new images of Mars during the meeting. They will also highlight the challenges faced from the recent dust storm that engulfed the entire planet, preventing high-quality imaging of the surface.


The Trace Gas Orbiter began its science mission at Mars in April, and while its primary goals are to provide the most detailed inventory of martian atmospheric gases to date – including those that might be related to active geological or biological processes – its radiation monitor has been collecting data since launch in 2016.



The Liulin-MO dosimeter of the Fine Resolution Epithermal Neutron Detector provided data on the radiation doses recorded during the orbiter’s six-month interplanetary cruise to Mars, and since the spacecraft reached orbit around the planet.


On Earth, a strong magnetic field and thick atmosphere protects us from the unceasing bombardment of galactic cosmic rays, fragments of atoms from outside our Solar System that travel at close to the speed of light and are highly penetrating for biological material.


In space this has the potential to cause serious damage to humans, including radiation sickness, an increased lifetime risk for cancer, central nervous system effects, and degenerative diseases, which is why ESA is researching ways to best protect astronauts on long spaceflight missions.


The ExoMars measurements cover a period of declining solar activity, corresponding to a high radiation dose. Increased activity of the Sun can deflect the galactic cosmic rays, although very large solar flares and eruptions can themselves be dangerous to astronauts.

“One of the basic factors in planning and designing a long-duration crewed mission to Mars is consideration of the radiation risk,” says Jordanka Semkova of the Bulgarian Academy of Sciences and lead scientist of the Liulin-MO instrument.


“Radiation doses accumulated by astronauts in interplanetary space would be several hundred times larger than the doses accumulated by humans over the same time period on Earth, and several times larger than the doses of astronauts and cosmonauts working on the International Space Station. Our results show that the journey itself would provide very significant exposure for the astronauts to radiation.”



The results imply that on a six-month journey to the Red Planet, and assuming six-months back again, an astronaut could be exposed to at least 60% of the total radiation dose limit recommended for their entire career.



The ExoMars data, which is in good agreement with data from Mars Science Laboratory’s cruise to Mars in 2011–2012 and with other particle detectors currently in space – taking into account the different solar conditions – will be used to verify radiation environment models and assessments of the radiation risk to the crewmembers of future exploration missions.



A similar sensor is under preparation for the ExoMars 2020 mission to monitor the radiation environment from the surface of Mars. Arriving in 2021, the next mission will comprise a rover and a stationary surface science platform. The Trace Gas Orbiter will act as a data relay for the surface assets.


The ExoMars programme is the result of cooperation between the European Space Agency (ESA), the Russian Space Agency (Roscosmos) and the Italian Space Agency (ASI). The ExoMars 2016 mission consists of an orbiter, the TGO (Trace Gas Orbiter), assembled at the Thales Alenia Space site in Cannes, with three scientific instruments and a high-resolution camera on board, and of a descent module, the EDM (Entry descent landing Demonstrator Module), which was assembled at the Turin site, equipped with scientific instruments for the physical and meteorological characterization of the atmosphere of Mars, a laser reflector and a video camera that is active during descent.  


Leonardo-Finmeccanica also contributed to ExoMars 2016, providing star trackers, photovoltaic panels, electronic supply units and the optronic heart of the video camera, CASSIS. Leonardo is also developing the diamond-drill that will set off in 2020 to dig into the surface of Mars to a depth of 2 metres, in search of traces of life.   

Lastly, Telespazio (Leonardo-Finmeccanica 67%, Thales 33%) is responsible, through the subsidiary Telespazio VEGA Deutschland, for the development of several key systems of the mission ground segment.