Space Radiation: A Hazard Defined

Solar and Galactic Radiation: A Hazard to Human and Equipment Safety in Deep Space

The year is 2025. NASA's Artemis mission has just landed on the Moon. The crew of four astronauts, two men and two women, are the first humans to set foot on the Moon in over 50 years. They are excited to be there, but they are also aware of the dangers that they face. The Moon is bombarded with radiation from the Sun and from deep space. The crew's spacesuits and the lunar lander are only partially shielded from radiation, so they are at risk of developing similar or more severe health issues than the Apollo astronauts who returned from the Moon. The crew is aware of the risks, but they are determined to succeed on their mission.

Radiation is a major hazard to human and equipment safety in deep space. The Earth's atmosphere and magnetic field protect us from most of the radiation that is present in space, but these protections are not present on the Moon or other celestial bodies.

There are two main types of radiation that are a concern in deep space:

• Ionizing radiation: Ionizing radiation is radiation that has enough energy to knock electrons out of atoms, creating ions. Ionizing radiation can damage DNA, which can lead to cancer and other health problems.
• Non-ionizing radiation: Non-ionizing radiation does not have enough energy to knock electrons out of atoms. However, non-ionizing radiation can still heat up tissues, which can cause burns.

The amount of radiation that a person can withstand varies depending on the type of radiation and the dose. Normal activities expose us to anywhere from 0.05 microsieverts (uSv) to 40 uSv — tiny fractions of what would be a dangerous dose.

According to estimates, astronauts in a spacesuit on the lunar surface could be exposed to around 60 microsieverts (uSv) of radiation every hour. Overall, the radiation level exposure could shoot up to 150 times higher than a normal person receives on Earth.

Radiation measured at 2 Sieverts (Sv) can become fatal without care due to severe damage to vital organs and tissues. Once neurovascular effects, including dizziness, severe headache, and decreased levels of consciousness, occur, Acute Radiation Syndrome (ARS) is invariably fatal. Fatality can occur at 4 Sv without prompt treatment and death occurs without fail at 8 Sv.

Defense Against Solar & Galactic Radiation

The Global Space Organization (GSO) is working to develop ways to protect humans and equipment from the harmful effects of radiation in deep space. Some of the techniques that the GSO is considering include:

• Using lunar regolith to build habitats: Lunar regolith (Moon Dirt) is the loose, powdery material that covers the Moon's surface. It is made up of small particles of rock, glass, and metal. Lunar regolith is a good absorber of radiation, so it can be used to build thick walled habitats that will protect humans from radiation exposure.
• Using advanced polymer coatings: Advanced polymer coatings can be used to absorb radiation. These coatings are made of materials that have a high hydrogen content, which makes them more effective at absorbing radiation.
• Using superconductors to create magnetic fields: Superconductors are materials that lose all electrical resistance when they are cooled to very low temperatures. Magnetic fields can be created by running an electric current through a superconductor. These strong magnetic fields can be used to help deflect radiation away from our habitats and exterior workspaces.
• Using lunar lava tubes: Lunar lava tubes are long, cave-like structures that were formed by ancient lava flows. These tubes are shielded from radiation by the surrounding rock, so they could be used to build safe and secure habitats in deep space, fully protected against radiation and micrometeorites.

The GSO is also considering other techniques for protecting humans and equipment from radiation exposure in deep space.

• Using other forms of radiation shielding: Radiation shielding can be used to protect humans and equipment from radiation exposure. Radiation shielding can be made of materials that are good at absorbing radiation, such as lead and even water. Leaded glass can also be utilized for windows that can absorb radiation yet still provide fantastic views of the lunar landscape.
• Using time-sharing: Time-sharing is a technique that can be used to reduce the amount of radiation exposure that humans receive. Time-sharing involves scheduling activities that involve exposure to radiation so that they are done during times when the surface radiation is at safe levels.
• Establish antioxidant rich diets: There are a number of antioxidants, including caffeine, melatonin, flavonoids, polyphenols, and other phytochemicals (e.g., albana), which are shown to decrease radiation-induced damage in either plasmid or cellular DNA through the scavenging of oxygen radicals and/or peroxides.

The GSO is committed to developing safe and effective ways to protect humans and equipment from the harmful effects of radiation in deep space. The techniques that the GSO is considering have the potential to make deep space exploration safer and limit the hazards of deep space radiation.