NASA is nervous about sending astronauts to Mars because exposure to the wind of high-energy particles streaming from the sun could indeed prove deadly. But a team of researchers at the Rutherford Appleton Laboratory (RAL) near Oxford, UK, have shown that a magnet no wider than your thumb can deflect a stream of charged particles like those in the solar wind. It gives new life to an old idea about shielding spacecraft, and might just usher in a new era of space travel.