ExoMars Highlights Radiation Risk for Mars Astronauts and Observes Decline in Dust Storm

The orbiter filming crew also presents new footage of Mars at the meeting. They will also highlight the challenges posed by the recent dust storm that engulfed the entire planet, preventing high-quality imaging of the surface.

Radiation monitoring

The Trace Gas Orbiter began its scientific mission to Mars in April and, while its main objectives are to provide the most detailed inventory of Martian atmospheric gases to date – including those that may be related to geological or biological processes collecting data since its launch in 2016.

The Liulin-MO dosimeter of the Fine Resolution Epithermal Neutron Detector (FREND) provided data on radiation doses recorded during six months of interplanetary cruise to Mars, and since the spacecraft has reached orbit around the planet.

On Earth, a strong magnetic field and a thick atmosphere protect us from the incessant bombardment of galactic cosmic rays, fragments of atoms outside our solar system that move at a speed close to that of light and penetrate strongly into biological material. .

In space, this can cause serious damage to humans, including radiation disease, increased risk of cancer, effects on the central nervous system and degenerative diseases. That's why ESA is looking for ways to best protect astronauts during long space missions.

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

"One of the fundamental factors in the planning and design of a long-duration crewed mission on Mars is the consideration of radiological risk," says Jordanka Semkova of the Bulgarian Academy of Sciences. science and main scientist Liulin-MO instrument.

"The radiation doses accumulated by astronauts in the interplanetary space would be several hundred times higher than the human accumulated doses over the same period and several times higher than the doses of astronauts and cosmonauts working on the international space station. the trip itself would give astronauts a very high exposure to radiation. "

The results imply that on a six-month trip to the red planet, and assuming that six months ago, an astronaut could be exposed to at least 60% of the total radiation dose limit recommended for all his career.

The ExoMars data, which is in good agreement with Mars Science Laboratory's Mars cruise data in 2011-2012 and with other particle detectors currently in space, taking into account the different solar conditions, will be used to verify the models. radiation risk for crew members of future exploration missions.

A similar sensor is being prepared for the ExoMars 2020 mission to monitor the radiation environment from the surface of Mars. Arrived in 2021, the next mission will include a mobile and a stationary scientific platform on the surface. The Trace Gas Orbiter will act as a data relay for surface assets.

The global dust storm is decreasing

Radiation is not the only danger facing the Mars missions. A global dust storm that engulfed the planet earlier this year has resulted in a significant reduction in light levels at the surface, resulting in NASA's rover Opportunity in hibernation. The solar-powered mobile has been silent for more than three months.

In orbit 400 km above the surface, the ExoMars Trace Gas Orbiter surface color and stereo imaging system, CaSSIS, also suffered. As the planet's surface is almost completely obscured by dust, the camera has been shut down for most of the storm period.

"Normally, we do not like to broadcast images like this (right), but it does show that the dust storm prevents useful imaging of the surface," says lead camera scientist Nicolas Thomas. from the University of Bern. "We had images that were worse than that when we looked at the conditions from time to time and that it was not too logical to try to look through the" soup "."

But the camera team discovered that even a cloud of dust had a positive aspect.

"Observations obscured by dust are actually pretty good for calibration," explains Nicolas. "The camera has a small amount of light and we used dust storm images to find the source of the projector and start deriving algorithms to remove it."

Since August 20, CaSSIS has resumed imaging 24 hours a day.

"We still have some pictures affected by the dust storm, but they are coming back to normal and we already have a lot of quality images down since the beginning of September," adds Nicolas.

An image acquired on September 2 (shown here at the top of the page), although not completely devoid of artifacts, shows dark streaks that could be related to the storm itself. One possible interpretation is that these features were produced by "dust devils" – swirls – stirring loose surface materials. The region, Ariadne Colles, in the southern hemisphere of Mars, was photographed by NASA's Mars Reconnaissance Orbiter camera in March, before the storm, and there appeared to be few traces of these trails.

"We are very pleased to discuss the first scientific results of this week's ExoMars Trace Gas Orbiter program, as well as progress on the next surface mission," says Håkan Svedhem, Trace Gas Orbiter Project Scientist. # 39; ESA.

"While our instrument teams are working hard to analyze the details of the atmospheric gas inventory and prepare these results for publication, we are certainly pleased to be able to contribute to storm-related discussions." dust and on the essential issues for future crewed missions to Mars. "

Explore more:
Image: Frosted crater on Mars