Crewed missions to Mars remain an essential goal for NASA, but scientists are only now beginning to understand and characterize the radiation hazards that could make such ventures risky, concludes a new paper by University of New Hampshire scientists.
In a paper published online in the journal Space Weather, associate professor Nathan Schwadron of the UNH Institute for the Study of Earth, Oceans, and Space (EOS) and the department of physics says that due to a highly abnormal and extended lack of solar activity, the solar wind is exhibiting extremely low densities and magnetic field strengths, which causes dangerous levels of hazardous radiation to pervade the space environment.
“The behavior of the sun has recently changed and is now in a state not observed for almost 100 years,” says Schwadron, lead author of the paper and principal investigator for the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on NASA’s Lunar Reconnaissance Orbiter (LRO). He notes that throughout most of the space age, the sun’s activity has shown a clockwork 11-year cycle, with approximately six- to eight-year lulls in activity (solar minimum) followed by two- to three-year periods when the sun is more active. “However, starting in about 2006, we observed the longest solar minimum and weakest solar activity observed in the space age.”
These conditions brought about the highest intensities of galactic cosmic rays seen since the beginning of the space age, which have created worsening radiation hazards that potentially threaten future deep-space astronaut missions.
“While these conditions are not necessarily a showstopper for long-duration missions to the moon, an asteroid, or even Mars, galactic cosmic ray radiation in particular remains a significant and worsening factor that limits mission durations,” says Schwadron.