P069-0014
Radiation Shadowing at Butte M12 in the Murray Buttes Formation

Tuesday, 15 December 2020
Poster
Bent Ehresmann1, Don Hassler2, Cary Zeitlin1, Robert F Wimmer-Schweingruber3, Jingnan Guo4 and Gunther Reitz5, (1)Southwest Research Institute Boulder, Boulder, CO, United States, (2)Southwest Research Institute, Boulder, CO, United States, (3)University of Kiel, Institute for Experimental and Applied Physics, Kiel, Germany, (4)University of Science and Technology of China, Hefei, China, (5)German Aerospace Center DLR Cologne, Cologne, Germany
Abstract:
Protecting astronauts from the effects of space radiation remains one major stepping stone for the exploration of Mars. Long-term exposure to radiation can lead to severe health effects and affects allowable mission durations.

On Mars, the radiation field is dominated by primary Galactic Cosmic Rays (GCRs) and secondary particles created by GCR interactions with atmosphere and soil. On short time scales sporadic Solar Energetic Particles (SEPs) can dominate the radiation environment, thereby increasing the radiation dose by orders of magnitude.

Common mission designs for Mars include the use of radiation shelters that provide additional mass to surround the astronauts. This leads to incoming radiation losing energy through ionization processes. This is important during SEP events when solar protons can reach the surface with high intensities. As SEPs on Mars usually only reach a few hundred MeV of energy, such shelters can reduce the radiation exposure drastically. Additionally, they provide a long-term reduction of the exposure to high-energy GCRs.

While it is possible to transit such additional material from Earth to Mars, mass is an important time and cost factor in space travel, limiting the amount of material that can be brought on one trip. Therefore, using natural sheltering already on Mars is a desirable option. One prime candidate is to station the astronaut base in subterranean lava tubes, providing shelter from the radiation from above. Other options include craters, cliff walls, or rock overhangs. However, the radiation sheltering provided by such features had previously not been measured or quantified in-situ.

Here, we present the first measurements of radiation shadowing / sheltering by natural rock formations taken on the surface of Mars. The data were acquired with the Radiation Assessment Detector (RAD) on board the Curiosity rover in Gale crater on Mars. We show measurements from a time frame when Curiosity was parked close to Butte M12 in the Murray Buttes formation. During this time, from MSL sol 1456 to 1467, respectively September 9 to 21 2016, we find a decrease in the expected dose rate. We analyze different RAD detector read-outs to qualify and quantify this radiation decrease in terms of dependence on the incident angular range, as well as on the particle species of the radiation.

<< Previous Abstract | Next Abstract >>