Radiation and Human Space Exploration

Where does radiation come from?

Radiation is everywhere on Earth. It is in the air, water, food, soil, and in all living organisms. Radiation also comes from the Sun and other stars. This is called cosmic radiation. 

Cosmic radiation includes two types of radiation. Electromagnetic radiation is made up of rays such as gamma rays or X-rays. Particle radiation can include neutrons, alpha particles, or beta particles. These come from the nuclei of heavy atoms such as iron.

Fortunately, Earth’s atmosphere and magnetosphere (magnetic field) help absorb and filter this radiation. Some radiation does pass through these protective barriers. However, we are protected from high doses of cosmic radiation.

What are the Dangers of Radiation for Human Space Travel?

Cosmic radiation is one of the greatest dangers for people travelling into space. Cosmic ray particles are charged particles that are highly energetic. They are a form of ionizing radiation. This type of radiation is dangerous to people and machines in space. When these particles collide with the particles of other objects, they can split their molecules. This can result in the formation of secondary particles, such as neutrons and other subatomic particles.

As you have learned, radiation can come from neutrons, alpha particles, beta particles and gamma rays. But neutrons penetrate matter at a deeper level than other forms of radiation. In humans, neutron radiation can damage cells or cause them to mutate. These cells may become cancerous, or die. 

Because of the dangers of cosmic radiation, scientists are concerned about its impact on humans. They are especially concerned about astronauts and cosmonauts who spend long periods of time in space. 

Spacecrafts have special shielding that helps stop cosmic radiation from penetrating the inside of the craft. Spacesuits are designed to do the same thing. These spacesuits are particularly important for astronauts visiting the Moon, Mars, or asteroids.

Even though we have these precautions, scientists still are not sure how extended exposure to cosmic radiation impacts astronauts and cosmonauts. Scientists think that prolonged exposure to cosmic radiation might cause cancer or heart disease. But according to a 2019 study, people who have travelled to space so far are no more likely to die of cancer or heart disease than people who have not. This may be because most astronauts and cosmonauts have travelled to low Earth orbit. There, the Earth’s magnetic field still protects them. Also, astronauts and cosmonauts do not usually spend more than a few consecutive months in space. But scientists worry about how longer trips in deep space will affect space travellers. For example, how will cosmic radiation impact people who visit Mars?

Did you know?

The record for most consecutive days in space is held by Russian cosmonaut Valery Polyakov. His flight aboard the Mir Space Station from 1994 to 1995 lasted 438 days, or about 15 months.

We still have a lot to learn about cosmic radiation’s long-term effects on humans in space. Scientists are learning more about this topic every day. They are doing experiments at the NASA Space Radiation Laboratory in Brookhaven, NY and on the International Space Station!