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Cairo – Samia Sayed – The prospect of sending astronauts on a 6- to 9-month journey to Mars presents many challenges, not to mention the risks they will face while conducting scientific operations on the surface, according to an RT report.
In the next decade, the US space agency and its Chinese counterpart plan to send the first manned missions to Mars, and this will consist of sending both agencies to spacecraft in 2033, 2035 and 2037, and every 26 months thereafter to coincide with the opposition of Mars (that is, when Earth and Mars are as close as possible to their orbits). .
The long-term goal of these programs is to create a base on Mars that will serve as a hub for future missions, although the Chinese have said they intend their base to be permanent.
In a recent study, an international team of scientists surveyed the Martian environment, from the tops of Mount Olympus to its underground recesses, to find the lowest level of radiation. Their findings could benefit future missions to Mars and create habitats on Mars.
And when it comes to missions to Mars and other locations outside Low Earth Orbit (LEO), radiation is always a constant concern. Compared to Earth, Mars’ atmosphere is weak (less than 1% of air pressure), and there is no protective magnetosphere to protect the surface from solar and cosmic radiation.
As a result, scientists hypothesize that harmful particles, especially galactic cosmic rays (GCRs), can propagate and interact directly with the atmosphere and even reach the surface of Mars.
However, the level of radiation exposure depends only on how thick the atmosphere is, which changes due to altitude.
In low-lying areas such as Mars’ famous valley system (Valles Marineris) and its largest crater (Hellas Planitia), atmospheric pressures are estimated to be more than 1.2 and 1.24 kPa, respectively. This is about twice the average 0.636 kPa and up to 10 times the atmospheric pressure at high altitude locations such as Olympus Mons (the largest mountain in the Solar System).
“Different altitudes mean different atmospheric thicknesses. Generally higher places have an atmosphere,” Dr. Jingnan Gu, a Christian Albrecht University professor and a member of the Chinese Academy of Sciences (CAS), co-author Professor Jian Zhang, explained to Universe Today via email. “Thinner at the top. High-energy particle radiation needs to pass through the atmosphere to reach the surface of Mars. If the thickness of the atmosphere changes, the surface radiation may change as well. So altitude can affect the radiation from the surface of Mars.”
To this end, the team looked at the effect of the depths of the atmosphere on Mars’ radiation levels.
The scientists found that higher surface pressures can effectively reduce the amount of heavy ion radiation (GCRs), but additional protection is still needed.
Unfortunately, the presence of this shielding can lead to “cosmic ray showers”, where the effect of heavy ion radiation against the shielding creates secondary particles that can engulf the habitat with different levels of neutron radiation (also known as neutron flux).
This could contribute significantly to the effective dose of radiation absorbed by the astronauts.
The team notes that both the neutron flux and the effective dose peak at about 30 cm (1 ft) below the surface. Fortunately, these results offer solutions for the use of the Martian regolith for protection.
For a given threshold of annual biologically weighted effective dose of radiation, for example, 100 mSv (an amount often considered the minimum risk of radiation-induced cancer), the required regolith depth ranges from about 1 m to 1.6 m. m. Within this range, in a deep pit where the surface pressure is higher, the additional regolith shielding needed is slightly smaller. Whereas at the top of Mount Olympus, the additional regolith protection required is higher.”
Based on their findings, the best locations for future habitats on Mars would be in the lowlands, at depths of 1 meter and 1.6 meters (3.28 to 5.25 feet) below the surface. Therefore, the northern lowlands, which make up most of the Northern Hemisphere (also known as Vastitas Borealis), and the Valles Marineris Valley would be very suitable sites. In addition to having thicker atmospheric pressure, these areas also contain abundant water ice just below the surface.
And if all goes according to plan, astronauts will be on Mars in just over a decade. This will consist of transits lasting six to nine months (excluding the development of more advanced propulsion technology) and surface operations of up to 18 months.
In short, astronauts will have to contend with the elevated radiation risk for up to three years. As such, detailed mitigation strategies must be developed early.
“Our study may help mitigate radiation risks when designing future Martian habitats using natural surface materials as protective shields,” said Dr. Jo. “So such research will be of great value when mission planners begin to consider designs for future Martian habitats that rely on energy-saving materials. Natural surfactants to provide radiation protection.