Feb. 19, 2008 -- For more than 40 years, NASA has kept tabs on astronauts' heart rates, respiration, temperature and dispositions as they ventured outside their ships to work in open space.
But it wasn't until the spacewalks by shuttle Atlantis astronauts last week that the U.S. space agency attempted to track how much solar radiation they might be exposed to during their outings.
"We're testing this model to see if it can be used in an operational situation," said Stephen Guetersloh, a particle physicist with NASA's Space Radiation Analysis Group at the Johnson Space Center in Houston told Discovery News.
Taking data from instruments aboard the now orbiting Solar Heliospheric Observatory, or SOHO, scientists are attempting to correlate solar activity with the approach of highly energetic particles that could pose a health threat to spacewalking astronauts.
The system is intended to give NASA about an hour advance warning of potentially threatening radiation, said Arik Posner, with the Texas-based Southwest Research Institute.
"Although it seems relatively short notice, the warning can be mission-critical," said Posner, pointing to the spacewalks that will be required when NASA returns astronauts to the lunar surface.
Earth's magnetic field provides a protective bubble for people on the ground and most of the time for spaceships, like the International Space Station and space shuttles, in low-Earth orbit.
Because the sun is currently in a quiet phase of its 11-year cycle, astronauts face a relatively low risk of dangerous radiation exposure. That will change over the next few years, as the sun heads into a period of maximum activity in 2010 or 2011.
The forecasting technique is attempting for the first time to predict the onset of damaging solar particles by measuring the amount of free-flying solar electrons, which are easily detected well ahead of the dangerous protons that follow.
Exposure to ionizing radiation increases the chances of cancer and other diseases. Combating radiation exposure is one of the primary concerns of long-duration space flight, particularly beyond low-Earth orbit.
"As space exploration leads humans out of this protective magnetic cocoon … methods of space weather forecasting will become increasingly important," Posner said.
Related Links:
Irene Klotz's blog: Space Diary
Space Radiation Analysis Group