Mars has a "bad reputation" for its high exposure to radiation and it has
neither a magnetic field nor a thick atmosphere to shelter its surface from
high energy particles from outer space.
In a study published in Geophysical Research Letters, Guo Jingnan from
University of Science and Technology of China (USTC) of the Chinese Academy
of Sciences, and international collaborators, analyzed the data from the
Radiation Assessment Detector (RAD) on the Curiosity rover, and proposed a
possible way to mitigate radiation on Mars.
The Curiosity rover launched in November, 2011 and landed on Mars in August,
2012. It was dedicated to searching for the elements of life on Mars. In
September, 2016, Curiosity parked close to a butte and detected a reduction
in radiation dose, and when Curiosity traversed far from the butte, the dose
came back to normal. The researchers attributed this change in radiation
dose to topographical variations.
They then plotted the panoramic sky visibility map of RAD for further
investigation. They found that about 20% of the sky was blocked when
Curiosity rover was near the butte, and the number was less than 10% before
getting close to the butte, which suggested that surrounded buttes did
shield a portion of radiation.
Moreover, the researchers developed a model of the zenith angle dependence
of the dose through Monte Carlo model, and found that the dose reduction
predicted by this model is significantly higher than the observation.
They explained that the obstructing butte may contribute to additional
albedo radiation, which was reflected by the terrain of Mars and emitted
backwards, and it is not completely safe hiding beside a butte because
although the radiation from above can be mitigated, the secondary radiation
reflected by the butte may increase.
Finally, based on RAD observation and a radiation transport model, the
researchers calculated the albedo radiation of the flat terrain on Mars
which is about 19% of total surface dose.
This study determined the influence of topology on radiation dose on Mars
and revealed the influence of buttes on albedo radiation on Mars, which
contributes to the understanding of the radiation environment on Mars and
the development of possible mitigation strategies.
Reference:
Jingnan Guo et al, Directionality of the Martian Surface Radiation and
Derivation of the Upward Albedo Radiation, Geophysical Research Letters
(2021).
DOI: 10.1029/2021GL093912
Tags:
Space & Astrophysics