Extravehicular Activity Radiation Monitoring (EVARM): Results

Caption: Flight Engineer Dan Bursch conducts an EVA outside the Quest airlock on February 20, 2002. This picture, captured from video shot by Commander Yuri Onufrienko using a camera mounted on the Canadian robotic arm, records the first EVA conducted outside the Quest airlock without an orbiter present. The first EVARM spacesuited measurements were taken during this EVA, which also included Flight Engineer Carl Walz. Both astronauts wore dosimeter badges inside pockets sewn onto their thermal comfort undergarments (TCUs) and another placed inside their communications carrier assemblies.

Results

Researchers
received the first spacesuited EVARM measurements on Wednesday, February
20, 2002, during a six hour EVA by Dan Bursch and Carl Walz. The EVA, which
was filmed by Yuri Onufrienko from inside the Station and broadcast live
on NASA TV, was also memorable because it was included as part of the celebration
marking the 40th anniversary of John Glenn’s Mercury-6 mission as the first
U.S. astronaut to orbit Earth. Bursch and Walz paused briefly during their
EVA tasks to commemorate the occasion. On Monday and Tuesday, the crew took
baseline reading with the dosimeters badges, and postflight readings were
taken on Friday.

NASA
has adopted the guidelines for space radiation exposure published by the
National Council on Radiation Protection (NCRP) in 1989.¹
These guidelines are as follows:

While
previous studies have measured the radiation dose received by crew on
spacecraft, EVARM is the first experiment to measure dose received during
extravehicular activities (EVAs). Improvements in dosimeter design and
miniaturization make it possible to conduct an experiment like EVARM without
interfering with EVA activity.

Applications

A complete
understanding of the space radiation environment and potential dose allows
NASA and other space agencies worldwide to plan mission activities, such
as EVAs, with crew long-term health in mind. EVARM and other space radiation
research provides the NCRP and the International Commission on Radiological
Protection the data necessary to create models and issue recommendations
for space radiation protection. Research results and recommendations from
research organizations guide the development of radiation shielding and
other countermeasures.

Shielding and countermeasures
developed for the space program can also be used on Earth to protect people
who work in high-radiation areas.

The
MOSFET dosimeters developed for space radiation monitoring experiments
like EVARM are already being used by doctors in the treatment of cancer
patients. The dosimeters’ small size allow them to be placed anywhere
on patients during radiation treatment, giving the medical practitioners
real-time, skin-specific data on radiation dose without interfering with
patient comfort. Furthermore, as demonstrated with EVARM, a single reader
can support multiple dosimeters. A single reader can be used for multiple
treatment rooms, saving practitioners and hospitals money.

Related Publications

¹National Council on Radiation Protection and Measurements (NCRP). 1989. Guidance on Radiation Received in Space Activities: Recommendations of the National Council on Radiation Protection and Measurements. NCRP Report No. 98. National Council on Radiation Protection and Measurements, Bethesda, MD.

J. Kiefer. 2001. Space radiation research in the new millenium—From where we come and where we go. Phys Med. 17 Suppl 1:1-4. [Abstract]

National Research Council, Space Studies Board. 2000. Radiation and the International Space Station:  Recommendations to Reduce Risk. Washington, DC:  National Academy Press.

I. Thomson. 1999. EVA dosimetry in manned spacecraft. Mutat Res. 430(2):203-9. [Abstract]

G.D. Badhwar. 1997. The radiation environment in low-Earth-orbit. Radiat. Res. 148: S3-S10.

G.F. MacKay, J. Dubeau, and I. Thomson. 1993. Radiation measurements on Russian spacecraft Mir and Bion 10. Proceedings of Spacebound 93 Conference. Canadian Space Agency, Ottawa, Canada. pp. 11-12.