Orbiter reveals Martian dust devils and high radiation counts

Astronauts travelling to Mars would experience 60% of their recommended career exposure to radioactivity in a single return journey, a conference has been told.

Scientists in charge of the ESA-Roscosmos ExoMars Trace Gas Orbiter – a combined European and Russian project that has been monitoring atmospheric gases around the red planet since 2016 – revealed to the European Planetary Science Congress (EPSC) in Berlin, Germany,  radiation readings gathered by the orbiter during its six-month voyage from Earth to Mars, and its subsequent orbit.

By doubling the travel-specific readings to account for the return voyage, the scientists calculate that the overall exposure experienced by Mars astronauts will be sufficient to limit their journeys to just one.

The data was gathered by a specialised piece of equipment called the Liulin-MO dosimeter, attached to the orbiter. The findings are in general agreement with particle detectors on board other space probes.

“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.{%recommended 6715%}

“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.”

At the same conference – which winds up on Friday, September 21 – another team of scientists working on the orbiter project released new images of the surface of Mars, taken as a monster dust storm begins to subside.

The storm, which hit earlier this year, forced NASA’s Opportunity rover to go into protective shutdown. Despite being 400 kilometres above the ground, the ExoMars orbiter was also affected, and has been unable to image the planet for several months.

With the dust at last waning, its onboard cameras are once again functioning. To celebrate, the team released an image of the Ariadne Colles region, in the planet’s southern hemisphere, taken on September 2.

The picture shows what the researchers cautiously describe as “dust devils” – possibly whirlwinds stirring up loose material from the surface. An earlier image of the same area, taken by NASA’s Mars Reconnaissance Orbiter, showed no evidence of similar disturbances, leading observers to suggest they are direct result of the storm.

“While our instrument teams are working hard analysing the details of the atmospheric gas inventory and preparing these results for publication, we are certainly pleased to already be able to contribute to topical discussions on the dust storm and on issues that are essential for future crewed missions to Mars,” says ESA project scientist Hakan Svedhem.