As the human race continues to explore the final frontier, it has become increasingly important to understand the effects of our exposure to space radiation.
Radiation is a type of energy produced in the form of rays, electromagnetic waves, and/or particles. There are forms of radiation that can be observed, such as visible light, and some forms that can be felt, like infrared radiation. X-rays and gamma rays are invisible forms of radiation that can only be seen with special instruments. For the most part, these are forms of radiation that we can be exposed to here on Earth. But, once we step outside the atmospheric boundaries of our planet, we will be exposed to space radiation.
Space radiation originates from matter ejected from stars. Due to the matters’ immense speed (almost the speed of light), the atoms in the stellar matter lose their electrons with only the nucleus remaining, resulting in the birth of space radiation. This cosmic radiation, together with gamma rays and neutral particles in interstellar space, exhibit varied impacts on man-made and natural objects. With the consequences in mind, it is crucial to understand the interactions of space radiation with our solar system in order to enhance the human experience not only on Earth but in space as well.
In cosmic radiation, there are three types we have to be aware of, all of which are high-energy, ionizing radiation. Firstly, there are radiation particles stuck within the Earth’s magnetic field, particles produced from solar particle events and galactic cosmic rays originating from outside our solar system. Ionizing radiation, such as gamma rays, x-rays, and galactic cosmic radiation, has enough energy to totally discard electrons, creating a more positively charged atom. On the other hand, there is low-energy, non-ionizing radiation, such as radio frequencies, visible light, and microwaves, that does not produce enough energy to remove electrons from matter it comes across.
While both ionizing and non-ionizing radiation can be damaging, the non-ionizing variety can be shielded. Ionizing radiation, however, is able to blast through materials in its way and alter it at the atomic level, leaving significant destruction behind. In space, ionizing radiation has been categorized into three types: galactic cosmic radiation (GCR), solar flare particles, and radiation belt particles (Van Allen Belts) trapped in space around our planet. But of the three different types, GCR happens to be the dominant source of radiation that our current space endeavors and future missions have to manage to safeguard their instruments and electronics.
Coming mainly from within our Milky Way, GCR are heavy, high-energy ions with only their nucleus remaining as all of their electrons have been stripped away when blasting through our galaxy at nearly light speed from being accelerated the last few million years by magnetic fields of supernova remnants. At that speed and with that intense energy, GCR can easily travel through a typical spacecraft or an astronaut’s skin.
The space radiation environment can pose a danger of causing radiation damage to spacecraft and their instruments. One such impairment is the ionization damage, where the radiation particle ionizes atoms of the material forming electron-hole pairs in them, causing severe degradation of semiconductor device performance and deteriorating the material’s physical and chemical properties. Therefore, it is vital to protect space instruments, vehicles and explorers against space radiation environments.
Back on Earth, cosmic radiation can also threaten human activities to a great extent. On Halloween of October 2003, three gigantic sunspots appeared on our Sun producing 17 solar flares, resulting in a series of intense solar storms hitting our planet, disrupting various technological systems essential for daily life. These geomagnetic storms made considerable damages and interruptions to electronics and technology both on ground and in space, from satellites and GPS to radio communication. Many space missions entered safe mode and some even had to shut down. Unfortunately, the Martian Radiation Environment Experiment aboard NASA’s Mars Odyssey mission got destroyed as well. The aerospace field was also severely affected when airline operations between North America and Asia over the North Pole was disrupted due to communications issues. GPS systems essential for surveying, deep-sea and land drilling, and other airline flights were hit hard as well.
There is much to be studied and understood about cosmic radiation if we want to continue the exploration of space in a safe manner. In fact, the space radiation environment is an ongoing study with much to be unraveled in order to obtain vital knowledge for future space missions and crewed spaceflights.