NASA wants to use active system to shelter crews from lower-energy cosmic radiation

NASA physicists are seeking funds to explore the use of electrostatic fields to protect astronauts from radiation on long space flights. Active shields able to deflect charged particles could reduce the weight of passive shielding required to shelter crews from cosmic radiation and the threat from solar storms.

Electrostatic shielding was first considered during the 1950s and 1960s, but the enormous field needed to deflect the high-energy protons and positive ions was considered a hazard because it attracted thermal electrons. Now NASA is studying a new concept, the multipole electrostatic shield, as a lightweight way of deflecting negatively and positively charged particles.

Mounting negatively charged spheres at the ends of booms extending either side of the spacecraft would create a positively repulsive zone around the vehicle, while repelling thermal electrons from a large region around the craft. Simulations suggest passive shielding would still be needed to stop high-energy galactic cosmic radiation, but researchers believe active electrostatic shielding could protect the crew during the lower-energy solar particle events.

"Galactic radiation is low-level and constant, but very high energy. Solar storms are lower energy, but very high quantities and very erratic," says Dr Robert Youngquist, head of the Kennedy Space Center applied physics laboratory.

Current plans call for astronauts to use a small, heavily shielded storm shelter, but with solar particle events lasting five or more days this could debilitate the crew and affect their ability to respond to emergencies during a radiation storm. Youngquist believes the electrostatic shield could even allow an astronaut caught outside the spacecraft during a storm to continue working.

Mylar-coated spheres 3-5m in diameter would be mounted at the ends of 15-30m-long booms and charged to at least 100MV. This would block particles up to energy levels of 100MeV and stop most solar radiation, and NASA is looking to push active shielding up to 300-500MeV, still well short of the 1GeV level of cosmic radiation.

GRAHAM WARWICK / WASHINGTON DC

Source: Flight International