As Astronauts Walk, NASA Keeps Tabs on Radiation

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

Solar Heliospheric Observatory, or SOHO

How Stuff Works: Spacesuits