A Force Field For Astronauts

Researchers are reviving an old but wild idea to protect astronauts from space radiation

Opposite charges attract. Like charges repel. It's the first lesson of electromagnetism and, someday, it could save the lives of astronauts.

NASA's Vision for Space Exploration calls for a return to the Moon as preparation for even longer journeys to Mars and beyond. But there's a potential showstopper: radiation.

Space beyond low-Earth orbit is awash with intense radiation from the Sun and from deep galactic sources such as supernovas. Astronauts en route to the Moon and Mars are going to be exposed to this radiation, increasing their risk of getting cancer and other maladies. Finding a good shield is important.

Supernovas produce dangerous radiation.

The most common way to deal with radiation is simply to physically block it, as the thick concrete around a nuclear reactor does. But making spaceships from concrete is not an option. (Interestingly, it might be possible to build a moonbase from a concrete mixture of moondust and water, if water can be found on the Moon, but that's another story.) NASA scientists are investigating many radiation-blocking materials such as aluminum, advanced plastics and liquid hydrogen. Each has its own advantages and disadvantages.

Those are all physical solutions. There is another possibility, one with no physical substance but plenty of shielding power: a force field.

Most of the dangerous radiation in space consists of electrically charged particles: high-speed electrons and protons from the Sun, and massive, positively charged atomic nuclei from distant supernovas.

Like charges repel. So why not protect astronauts by surrounding them with a powerful electric field that has the same charge as the incoming radiation, thus deflecting the radiation away?