Sun may rise, after all, on faulty space probe
Scientists are hopeful they can retrieve particles of solar wind from a capsule that crashed in the desert last week.
Genesis is getting a new lease on life - one shard at a time.
The $246-million mission to return pristine samples of the solar wind nearly ended as an unwanted experiment in carving craters in the Utah desert when its parachutes failed and the sample-return capsule burrowed into the desert floor last week.
Now, after carefully inspecting the inside of the wrecked capsule with a flashlight and with a mirror at the end of a stick, the somber mood has shifted to guarded optimism. Enough of the samples were found intact that researchers say they are confident they can salvage most of the science objectives they set out to accomplish.
"The science team is really excited," says Roger Wiens, one of the project's lead scientists. "We should be able to meet many, if not all, of our primary science goals."
Launched in August 2001, the Genesis spacecraft was designed to orbit a point beyond the influence of Earth's magnetic field to gather samples of charged particles that constantly stream from the sun's outer atmosphere. Because the sun holds 99 percent of all the matter in the solar system, researchers believe that studying these particles will tell them a great deal about the composition of the cloud of dust and gas from which the sun and planets emerged some 4.6 billion years ago.
By comparing the relative abundance of key elements in the solar wind with those found in the solar system today, researchers also say they may be able to better explain how the solar system emerged with such a wide variety of objects with varying compositions.
To corral the samples, the craft contained arrays of hexagonal wafers made from a range of highly purified materials - from silicon and gold to sapphires and diamonds. For three years it gathered samples, atoms at a time. But the wafers were fragile. A hard landing was out of the question. The capsule's parachute system was to have slowed the craft to about about 10 miles an hour. Even that was too fast. The capsule was to have been snagged in midair by one of two helicopters piloted by some of Hollywood's most experienced stunt pilots. That didn't happen.
Instead, as the craft tumbled earthward last Wednesday, the chutes failed to deploy, and the 450-pound capsule slammed into the desert floor at the US Army's Dugway Proving Ground at 193 miles an hour.
Both NASA headquarters and the Jet Propulsion Laboratory, which spearheaded the mission, have formed teams to investigate the crash. The incident is of additional concern because another sample-return mission, Stardust, is on its way home after encountering comet Wild 2 in January. Its hoard of cometary material and interstellar dust gathered earlier will return to Earth using systems similar to those on Genesis.
Even at the crash site, researchers found that some wafer shards had been ejected on impact. Genesis principle investigator Donald Burnett, a professor of geochemistry at the California Institute of Technology in Pasadena, took on the task of sifting through the soil to see if the samples in the shards were salvageable.
"I was concerned about prolonged exposure of these in the soil," he says. "So I got the job of picking them out. It's rather therapeutic."
The main experiment - a special collector designed to concentrate a large amount of solar-wind material in small areas - came through largely intact. The key now is to take what is left of the wafers and decontaminate them. The wafers were meant to be handled in a clean room. The solar-wind particles embedded themselves in the wafers to a depth of roughly 50 billionths of a meter, or 50 nanometers. But excessive exposure to ambient air allows contaminants to build up on the wafers' surfaces. The trick, mission officials say, is to find ways to remove the surface grunge without eating too deeply into the wafers.
"We may appeal to people in the semiconductor industry who have talents and procedures" for such decontamination efforts, Dr. Burnett says.
"You can be sure that these samples are not going to be touched until we know exactly how to keep them safe," adds Don Sevilla, the mission's payload-team leader.