In June, while beachgoers in Hawaii sit blissfully unaware, a flying saucer will descend over the island of Kauai. This is not a trailer for an alien invasion movie – NASA is gearing up to conduct the first test flight of a disc-shaped spacecraft designed to safely land heavy loads and one day people on the surface of Mars.

The Low Density Supersonic Decelerator (LDSD) will be lofted into the stratosphere from the US Navy's Pacific Missile Range Facility on Kauai. The inflatable technology is intended to help slow down vehicles after they enter the thin Martian atmosphere at supersonic speeds.

"It may seem obvious, but the difference between landing and crashing is stopping," says Allen Chen at NASA's Jet Propulsion Laboratory in Pasadena, California, who oversaw the successful landing of the one-tonne Curiosity rover in 2012. "We really only have two options for stopping at Mars: rockets and aerodynamic drag."

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