Space Flight and Radiation/Radiation on Other Planets

Q

I work in the airline industry as a crew member and want to know if there is there a way to find out what my radiation exposure might be?

A

There are several commercial firms that can provide individual dosimeters to interested passengers or crew members. It is extremely important to know that there are several types of radiation that contribute to a person's dose at flight altitudes. Any dosimeter that will be useful in this application must contain a suitable neutron measurement system. To locate current vendors of these products, one can search on  "radiation dosimetry services,"  "radiation dosimetry," or  "personnel radiation monitoring."

Q

What radiation doses would astronauts of an Apollo mission receive during solar flares?

A

During the past 30 years, several committees of the National Council on Radiation Protection and Measurements have evaluated the potential health-related effects which would be caused if a significant solar particle "storm" should occur during various activities performed by astronauts, including lunar or Mars missions. In a report issued in 1989, the NCRP estimated that if a major solar particle event occurred during a visit to the moon, it could give the astronauts doses to their skin of 6 sieverts (600 rem; both sievert and rem are units of radiation dose and sievert is commonly abbreviated Sv) with bone marrow doses of close to 0.9 Sv (90 rem). This amount of radiation exposure would not be life threatening. Actual radiation dose measurements of Apollo crews measured by onboard dosimetry were, on average, 12 mSv.

Q

What is the increase of ionizing radiation that one receives from a coronal mass ejection or solar flare that is aimed directly at the Earth?

A

The amount of any radiation increase depends on location. If you are in a spacecraft outside the Earth's magnetic field, the radiation doses can be quite large (as much as tens of sievert, 1 Sv = 100 rem; sievert and rem are units of radiation dose). If you are in a spacecraft, such as the Space Shuttle or International Space Station, the doses are lower (fractions of a sievert). Values depend on the altitude and inclination of the orbit and the amount of shielding provided by the spacecraft. In high-altitude aircraft (~65,000 ft), near the poles, doses from solar particle events are measurable, but not above limits for the general public. For most aircraft altitudes (below 45,000 ft), doses are negligible. A good source of information is the Proceedings of the 1998 Annual Meeting of the National Council on Radiation Protection and Measurements, which were published in the November 2000 issue of Health Physics.

Q

Where could I find information about proton radiation in space and information dealing with the penetration of protons in matter with energies typical of those found in space?

A

Since protons are present in the Van Allen belts, and in solar and galactic cosmic rays, places to search are various National Aeronautics and Space Administration (NASA) and National Oceanographic and Atmospheric Administration (NOAA) Web sites, including the NOAA Space Environment Center in Boulder, NASA Goddard and Marshall Space Flight Centers, the Jet Propulsion Laboratory, NASA Langley and Lewis Research Centers, NASA Johnson Space Center, and the education links on the NASA Headquarters Web site. Another source of information is the Proceedings of the Biennial COSPAR (Committee on Space Research) plenary meeting that are published in Advances in Space Research.

Representative URLs include:

• The Exploration of the Earth's Magnetosphere
• NASA Human Spaceflight
• Science @ NASA
• NOAA's Space Environment Center (Proton spectra and particle data from the GOES satellites can be viewed and downloaded for use.)  
• Cosmic Rays
• Solar-Terrestrial Physics Division of the National Geophysical Data Center.

Q

What are the radiation levels on the moon and Mars?

A

The radiation levels on the moon and Mars are similar and change with the approximate 11-year variation in the solar cycle. Radiation levels on Mars are probably lower than on the moon's surface because Mars has a thin atmosphere, composed mainly of carbon dioxide, that acts as a radiation shield. Estimates of radiation levels in deep space for thinly shielded spacecraft resulting from galactic cosmic rays range from ~ 0.3 Sv per year during solar maximum activity to ~ 1 Sv per year during solar minimum periods (L.W. Townsend, F.A. Cucinotta, and J.W. Wilson, "Interplanetary Crew Exposure Estimates for Galactic Cosmic Rays," Radiation Research 129, 48-52; 1992). A recent study of radiation levels and dose rates for a very large solar particle event is found in J.L. Parsons and L.W. Townsend, "Interplanetary Crew Dose Rates for the August 1972 Solar Particle Event," Radiation Research 153, 729-733; 2000.

Q

Where can I find data regarding doses and types of particles in normal and space flights?

A

Information regarding doses and radiation fields can be found in the following sources: 

1. Terrestrial sources and doses—NCRP Report Nos. 93 (Ionizing Radiation Exposure of the Population of the United States), 94 (Exposure of the Population of the United States and Canada from Natural Background Radiation), 95 (Radiation Exposure of the US Population from Consumer Products and Miscellaneous Sources), and 100 (Exposure of the US Population from Diagnostic Medical Radiation). 

2. Space Radiation—NCRP Symposium Proceedings No. 3 (Acceptability of Risk from Radiation - Application to Human Space Flight)

3. Commercial Aircraft—NCRP Commentary No. 12 (Radiation Exposure and High-Altitude Flight).

4. Proceedings of the 1998 NCRP Annual Meeting, No. 20 (Cosmic Radiation Exposure of Airline Crews, Passengers and Astronauts)

For information on ordering NCRP publications see the NCRP Web site.