Washington

Starter's orders: the Genesis mission aims to unlock the secrets of the Solar System's birth Credit: NASA

With the launch on 30 July of its Genesis spacecraft, researchers at NASA's Jet Propulsion Laboratory in Pasadena, California, will begin a three-year, $209-million study of the origin of the Solar System.

A Delta II rocket will take Genesis about a million miles from the Earth, to a position from which it will fly in a series of loops to collect particles from the solar wind. These will be sorted on board and brought back to Earth for analysis.

The haul, mainly of ions that have drifted away from the Sun's outer atmosphere into space, is expected to contain evidence of the solar nebula that marked the beginning of the Solar System around five billion years ago.

“The outer layer of the Sun preserves a fossil record of the chemical and isotopic composition of the solar nebula, the disk of gas and dust from which all the planets formed,” explains Donald Burnett of the California Institute of Technology, the principle investigator on the Genesis mission. The solar nebula is important, he says, because it was the transition phase between when “everything was just stardust” and the matter that now makes up the Solar System. If it succeeds, Genesis will provide insight into what happened during that transition.

John Leibacher of the National Solar Observatory in Tucson, Arizona, chairman of the American Astronomical Society's solar physics division, says that the materials in the solar wind “haven't undergone significant nuclear transformation in five billion years”.

Some of the Apollo Moon missions captured solar wind, but on a much smaller scale. Genesis will capture 10–20 micrograms of material over two years, using four instruments: collector arrays, an ion monitor, an electron monitor and an ion concentrator. “We have much purer materials to collect solar wind in now and we have much greater analytical capabilities,” says Burnett.

NASA also plans a spectacular homecoming for Genesis. Concerned that a parachute landing could disturb the samples, the agency will deploy helicopters to capture the spacecraft as it floats down.

→ http://genesismission.jpl.nasa.gov