Mars is bombarded with radiation. Without a protective magnetic shield and a thick atmosphere like that of Earth, space radiation has an almost free path from the Martian surface. Our machines can traverse the surface and face all this radiation with impunity.
But not humans. For humans, all this radiation is a deadly danger.
How can any potential human explorer cope? Well, they will need shelter. And they will have to take it along with them or build it somehow.
Or maybe not. Perhaps they could use natural elements as part of their protection.
A new study using data from Mars Science Laboratory (MSL) Curiosity has discovered how the features of Mars ’natural landscape can provide a refuge against radiation. Specifically, it shows how Martian blankets provide protection against high-energy particles in space.
The study is entitled “Directionality of Martian surface radiation and derivation of Albedo’s upward radiation” and is published in Geophysical research letters. The lead author is Guo Jingnan, from China University of Science and Technology.
When MSL Curiosity landed on the surface of Mars in 2012, it was carrying an instrument called a Radiation Assessment Detector (RAD).
RAD is trying to prepare for future human visits to Mars. Detects and measures harmful radiation on Mars from the Sun and other sources. It can also assess the danger that radiation poses to any microbial life that may exist on Mars. RAD is the size of a toaster and sits discreetly on the top surface of Curiosity.
One of the areas studied by MSL with RAD is the Murray Buttes region. The Murray Buttes region is located on the lower Sharp Mountain in Gale Crater. Curiosity was mainly there to study geology, especially the characteristics of sandstone and a type of layer called “cross beds”.
But while he was there, RAD was still collecting data. And these data showed a drop in surface radiation.
MSL Curiosity spent 13 suns parked near a butta in the Murray Buttes area. He mainly performed surface science and drilling operations while there. But RAD was also active, offering scientists a 13-day reading of radiation data in one place.
RAD data showed that while near the butte, there was a reduction in radiation dose of approximately 5%. The research team also built a sky visibility map, which showed that 19 percent of the sky was darkened when the rover was next to the mound.
This is not a scientific issue when it comes to protecting future human explorers from radiation, but it is important data.
There are more nuances to the data. While driving through the Murray Buttes area, Curiosity did not have an unobstructed view of the sky due to the terrain features. Thus, the team constructed the panoramic view of the sky from averages obtained over several previous months to compare them with the data collected during the 13-sun parking lot.
There are some approximations in these averages, but they will have to.
A map of the sky to illustrate the effect of the butte on radiation exposure. (Jingnan et al., GRL, 2021)
The red line with dots in the image above represents these approximations and averages.
RAD also found something else. The radiation that hits things, or people, on the surface of Mars originates from space. And most of the radiation that affects a person or a team comes directly from the sky.
But part of the radiation is albedo radiation, that is, it is reflected off the surface and hits objects from below. What did RAD find out about this?
It turns out that the same surface features that can offer protection against direct radiation can also increase reflected radiation. RAD showed that blankets can create an increase in this secondary reflected radiation. This is one of the complexities of understanding radiation on Mars.
The radiation dose to the surface of Mars is not consistent, but it fluctuates. Heliospheric changes can affect it, as can the angle of the sky to which explorers may be exposed. A sharper angle means that the radiation must travel through more atmosphere, which modifies the exposure to the surface.
Mars’ orbit changes its distance from the Sun, which also affects surface radiation. Lower altitudes will be exposed to less radiation than higher altitudes. And radiation is not a homogeneous phenomenon: there are protons, alpha particles, ions of various elements, neutrons and gamma rays.
Overall, the study helps paint a more complete picture of the Martian radiation environment. Much thought has been given to the on-site use of resources on Mars. The shelter is a major need for explorers on Mars, and if an advantage can be gained by using existing terrain features to protect them, those features will fit a mission profile somewhere.
There is already a lot of talk about laying bases in lava tubes, where people would be protected by meters of Martian regolith. But astronauts can’t spend all that time there. They will have to venture into radiation.
Any mission to Mars involving humans will need layers and layers of contingencies. In the event of an emergency, it will be vital to keep astronauts’ radiation doses as low as possible.
In fact, the entire mission will be planned to keep the annual exposure within limits. It’s not too hard to imagine planetary explorers making use of the radiation shelter they can while trying to fight equipment breakdown or any other setback.
Detailed radiation maps that take into account sky and terrain exposure and anything else that could save lives.
This article was originally published by Universe Today. Read the original article.