Nasa is preparing to launch a "flying saucer" into Earth's atmosphere to test technology that could be used to land on Mars.
For decades, Nasa has depended on the same parachute design to slow spacecraft after they enter the Martian atmosphere, but it needs a larger and stronger chute if it wants to land heavier objects and astronauts.
Weather permitting, a balloon carrying the saucer-shaped vehicle is set to launch from Hawaii.
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The vehicle will ignite its rocket engine and climb to 34 miles, and will then inflate a tube to slow itself down from supersonic speeds and unfurl a parachute for a water landing.
Engineers will analyse the data to determine if the test was successful. The test has been postponed several times because of high winds.