Utah-linked probe to gather comet dust

The probe has sailed through the silent depths of space for nearly five years and still has another two years to travel before it lands in Utah. But on Friday, it will carry out the central act of its daring program.

Stardust, a NASA project to gather dust from a comet, is drawing ever closer to Comet Wild 2 (pronounced Vilt 2). On Friday it flies within 190 miles of the nucleus.

It will be well inside the coma, the cloud of particles that spew from the comet. Flying along at 13,650 miles an hour, its collector devices gaping, it will gather bits of the comet and return them to Earth.

That return is scheduled for Jan. 15, 2006, when the probe is to settle by parachute onto the Utah Test and Training Range, an Air Force bombing range in this state's western desert.

During the crucial close approach to the comet, the spacecraft will be cruising "by the front side, between the comet nucleus and the sun," said Tom Duxbury, project manager for Stardust at the Jet Propulsion Laboratory, Pasadena, Calif. He talked with a Deseret Morning News reporter by telephone last week.

The collector device is filled with aerogel, billed as the world's least dense material. When the collector is struck by a particle from the swarm of dust and ice surrounding the comet, the aerogel slows the particle and captures it.

According to NASA, the nearly air-thin material will cause almost no damage to the particle. After the flyby, the collector will close like a clamshell so that the material can be returned safely to Utah.

Collection will take place for about two hours, he added. When it starts, instruments should detect a hit by a bit of cometary material about once a minute. The probe will take more and more hits as it approaches. "Right in the thick of it, we're getting dust hits every second," Duxbury said.

The spacecraft is also equipped with a camera that will get views of the nucleus. In fact, on Dec. 1 the camera photographed the comet from a distance of 15.5 million miles. The transmitted photo shows the comet looking like a flyspeck in space.

The camera's 200 mm telephoto lens will feed images to JPL, which the scientists will use to steer the probe toward the comet. During the flyby, other instruments will measure hits from cometary particles and calculate the size of the grains.

"We will land Jan. 15, 2006," Duxbury said. "Our little return vehicle is a version of the old Gemini or Apollo return capsules." It will re-enter Earth's atmosphere over the Pacific Ocean, protected by "this big heat shield," he said.