In a plot line worthy of a science fiction blockbuster, NASA scientists have hired Hollywood stunt pilots to stage a high-speed chase through the sky over Utah in a daring bid to catch a piece of the Sun before it crashes to Earth.
The helicopter pilots take off Wednesday to intercept a capsule from the Genesis spacecraft, which has travelled three years and 32 million kilometers (20 million miles) to capture atomic bits of solar wind that NASA hopes will help scientists understand what the Sun is made of and how the solar system began.
"We are bringing a piece of the Sun down to Earth," said Charles Elachi, director of NASA's Jet Propulsion Laboratory in Pasadena, California.
Two helicopters will try to catch the returning Genesis capsule before it hits the ground, which scientists fear could disrupt the solar particles.
The capsule is set to enter Earth's atmosphere at 11:55 am (1555 GMT) Wednesday over an air force base in the western state of Utah.
When it is 33 kilometers (108,000 feet) above ground, a drogue parachute will open to slow the capsule down. The main parachute will open six minutes later at an altitude of 6.1 kilometers (20,000 feet).
Then the two helicopters, each with a team of three people, will scramble to catch the capsule in midair.
The lead helicopter will deploy a six-meter (18-foot, 6-inch) pole with a giant, high-tech hook to catch the capsule by its parachute as it falls.
If the first chopper misses, the second will trail 300 meters (1,000 feet) behind and make another attempt.
The helicopters will have a total of five chances to intercept the capsule, according to flight operations director Roy Haggard, who heads the US firm Vertigo.
"These guys fly in some of Hollywood's biggest movies. But this time the Genesis capsule will be the star," Genesis project manager Don Sweetnam said.
The Genesis spacecraft was launched in August 2001 and sent to a precise point between the Earth and the Sun to catch bits of solar dust that could offer clues to how planets were formed.
The probe was positioned at a spot called Lagrange point 1, where the gravitational pulls of the Sun and Earth balance each other perfectly, and where Genesis had an uninterrupted view of the Sun away from Earth's magnetic field, which disrupts the solar winds.
The 494-kilo (1,000-pound) spacecraft used hexagonal wafers of silicon, gold, sapphire and diamond to capture 10 to 20 micrograms of the invisible bits of solar wind.
The samples will be the first samples returned to Earth from outside the Moon's orbit.
The wafers will be sent to the Johnson Space Center in Houston, Texas, for study.