New Insights into the Martian Radiation Environment gained with the MSL/RAD Investigation
Abstract
The Mars Science Laboratory / Radiation Assessment Detector (MSL/RAD) has been conducting detailed measurements of the radiation environment in Gale crater on Mars for more than 9 years. Understanding of this radiation field, its composition, and its temporal evolution are vital for the preparation of human exploration missions to Mars. Thereby, protecting astronauts from the effects of space radiation remains a critical step for the exploration of Mars. Long-term exposure to radiation can lead to severe health effects and affects allowable mission duration. Astronauts need to be protected from exposure to both the long-term Galactic Cosmic Ray (GCR)-induced radiation, as well as from short-term, but highly intense Solar Energetic Particles (SEPs). Here, we provide new insights into the changes the Martian radiation field has undergone since the beginning of the MSL mission in mid-2012 (close to solar maximum of solar cycle 24) throughout the deepest part of the solar minimum of cycle 24. We present how the evolving solar cycle has affected dosimetric quantities, such as the RAD-measured absorbed dose rate, Linear Energy Transfer (LET) spectrum, and the biologically highly-important dose equivalent rate. From these measurements, we make estimates of how much radiation astronauts would be exposed to under different mission scenarios and timing. Furthermore, we present new analysis of the natural radiation shielding effect of Martian terrain, measured for the first-time in-situ by MSL/RAD. We find that natural terrain, such as cliff sides or buttes, when high enough, block out part of the incoming GCR radiation, leading to an overall decrease in the measured dose rate. We present data from 5 occasions where such a shielding effect was observed by MSL/RAD and analyze how the angle of vertical obstruction of the natural terrain affects the measured decrease in dose. These first-ever in-situ measurements of the radiation shielding effect are crucial for the planning of radiation shelters for future Mars explorers by providing insight into the angular distribution of the radiation environment on the Martian surface. These measurements are vital to validate radiation transport models used to calculate the effectiveness of proposed radiation shelter designs.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.P24A..02E