Space Radiation
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Space is trying to kill you. It tries to kill you in many different ways. One of those ways is to flood itself with dangerous radiation that can kill biological organisms, damage or disable electronics, and degrade some kinds of materials.
Galactic Cosmic Rays
Space is filled with energetic charged particles – primarily protons but also including other light and medium ions. These are not associated with any immediate stellar environment but instead are thought to come primarily from supernovas and fill the galaxy with their radiation.
These cosmic rays generally have much higher energies than other forms of space radiation. A typical energy common to one of these particles would be around several hundred MeV to a GeV. Some have lower energies; these are often shielded from solar systems or planets by the sun's magnetic field, the solar wind, or planetary magnetospheres[1]. More notorious, however, are those with higher energies. Often much higher. The most energetic cosmic ray ever measured (as of 2024) had an energy of eV, or around 50 joules – the energy of a major league baseball pitch in a single particle[2].
High energy massive particles, such as these cosmic rays, will have a high gyroradius, so they will not be strongly deflected by magnetic fields. Consequently, more energetic cosmic rays can pierce a planets magnetosphere to deliver radiation dose to those in orbit.
Cosmic rays come through at a steady sleet, delivering on the order of Gy/day[3]. This dose is not delivered fast enough to cause acute radiation sickness, but is roughly two orders of magnitude higher than the natural background radiation dose on Earth. This can cause issues with chronic radiation exposure. The main concern is an increased risk of cancer. However, experiments on rodents exposed to radiation from a particle beam simulating long duration exposure to cosmic radiation also suggests the possibility of reduced cognitive function after several months in deep space[4]
Solar Radiation
Solar Ultraviolet Light
Solar Wind
Coronal Mass Ejections
Solar Flares
Flare Stars
Planetary Radiation Belts
Relativistic Travel
Stellar Corpse Environments
White Dwarfs
Neutron Stars
Magnetars
Black Holes
Supernovas
If you are near a supernova, space radiation is probably one of the smaller of your concerns. However, Type II supernovas are notable in being one of the only phenomena known that can produce dangerous levels of neutrino radiation. Neutrinos are normally so penetrating that they go through everything without significant interactions. However, the core collapse of Type II supernovas makes neutrinos in such prodigious quantities that enough of them can interact and cause radiation sickness and death within approximately the distance of the inner solar system[5].
Artificial Radiation Sources
The main focus of this article is on natural sources of radiation. But if you expect to operate in space you will also need to consider common artificial radiation sources. Many spacecraft and other space infrastructure are expected to be powered by fission or fusion reactors, or to use fission or fusion propulsion. All of these will produce copious amounts of nuclear radiation in the form of energetic neutrons, gamma rays, and the emissions of radioactive isotopes produced through fission or neutron capture. Without an atmosphere to attenuate the radiation produced, high power radiation sources can have an effect over a much larger distance than a similar unshielded source on Earth. This will produce a hostile radiation environment that will require large exclusion zones or shielding.
In addition, space conflict scenarios are likely to use particle beam weapons, x-ray or gamma-ray lasers, and nuclear explosives. All of these produce radiation as a primary effect or side effect of their operation.
Nuclear reactors and explosions in the vicinity of a planet with a magnetic field can make artificial radiation belts that persist for days to years (depending on the altitude), and can severely damage electronics operating within or passing through the belt[6][7].
Credit
Author: Luke Campbell
References
- ↑ Rahmanifard, F., de Wet, W. C., Schwadron, N. A., Owens, M. J., Jordan, A. P., Wilson, J. K., et al. (2020). Galactic cosmic radiation in the interplanetary space through a modern secular minimum. Space Weather, 18, e2019SW002428.
- ↑ D. J. Bird et al., "Detection of a Cosmic Ray with Measured Energy Well beyond the Expected Spectral Cutoff due to Cosmic Microwave Radiation", Astrophysical Journal v.441, p.144 (1995)
- ↑ https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015SW001175 Mazur, J. E., C. Zeitlin, N. Schwadron, M. D. Looper, L. W. Townsend, J. B. Blake, and H. Spence (2015), "Update on Radiation Dose From Galactic and Solar Protons at the Moon Using the LRO/CRaTER Microdosimeter", Space Weather, 13, 363–364, doi:10.1002/2015SW001175. The values given here are corrected for the roughly steradian shielding afforded by the moon.
- ↑ https://www.nature.com/articles/srep34774 Vipan K. Parihar, Barrett D. Allen, Chongshan Caressi, Stephanie Kwok, Esther Chu, Katherine K. Tran, Nicole N. Chmielewski, Erich Giedzinski, Munjal M. Acharya, Richard A. Britten, Janet E. Baulch, and Charles L. Limoli, "Cosmic radiation exposure and persistent cognitive dysfunction", Scientific Reports 6, 34774 (2016). https://doi.org/10.1038/srep34774
- ↑ R. Munroe, "Lethal Neutrinos", xkcd what if 73 (2013)
- ↑ G. F. Pieper, “The Artificial Radiation Belt”, APL Technical Digest (1962)
- ↑ John C. Ringle, Ludwig Katz, and Don F. Smart, "Electron and Proton Fluxes in the Trapped Radiation Belts Originating From an Orbiting Nuclear Reactor", Air Force Surveys in Geophysics, Report Number AD0608784 (1964)
