NASA capsule carrying comet dust en route to Earth

By Nichola Groom

LOS ANGELES (Reuters) – A space capsule loaded with comet
dust was barreling toward Earth after being released by its
mother ship late on Saturday following a seven-year, 2.9
billion-mile journey to recover materials formed at the dawn of
the solar system.

NASA’s Stardust mission, which will allow scientists to
study comet samples for the first time, ends early Sunday when
the 100-pound (45 kg) capsule is expected to land at the U.S.
Air Force Utah Test and Training range at 3:12 a.m. local time
(5:12 a.m. EST/ or 1012 GMT).

NASA scientists and engineers at the remote military
outpost were nervous but upbeat as they awaited the vessel’s
return, according to one Stardust team member.

“There is some tension,” said Chris Jones, director of
solar system exploration at NASA’s Jet Propulsion Laboratory.
“There are parts of the system that have never been used before
and they represent the unknown.”

In what was likely to assuage some of those concerns, the
Stardust spacecraft severed the umbilical cables between it and
the capsule as scheduled at 9:56 p.m. PST (12:56 a.m. EST on
Sunday/0556 GMT). One minute later, springs on the craft pushed
the capsule away. It is expected to enter the Earth’s
atmosphere roughly four hours later at a speed of 28,860 miles
per hour (46,440 km per hour), the fastest of any man-made
object on record.

The descent may be visible from the ground in northern
California, Oregon and Nevada.

HALFWAY TO JUPITER

Stardust’s mission, which began in 1999, took it around the
sun three times and halfway to Jupiter to catch particles from
comet Wild 2 in January of 2004. The dust was captured by a
tennis-racket-shaped space probe containing ice-cube-sized
compartments lined with aerogel, a porous substance that is
99.9 percent air.

The particles, most of which are expected to be a tenth as
wide as a piece of human hair, became lodged in the aerogel
before being shuttered inside the capsule.

Comets are thought to be leftovers from the process of
planet formation, and scientists hope the dust collected by
Stardust will give them clues about the origins of the solar
system 4.5 billion years ago.

“Capturing particles from a comet as it whizzes by is a way
of looking back in time,” Jones said.

Stardust’s mission marks the first time since 1972 that any
extraterrestrial solid material has been collected and brought
back to Earth. In 2004, a space probe called Genesis carrying
solar ions crashed to Earth when its parachute failed to open.

The Stardust capsule is also scheduled to deploy two
parachutes during its descent over the desert, though NASA
officials said they have prepared for the possibility of a hard
landing. Following both the Genesis incident and the 2003
Columbia shuttle disaster, the mission’s team spent six months
testing and reviewing the spacecraft’s design to make sure
there were no errors.

Shortly after landing, the capsule will be retrieved in the
desert by helicopters or ground vehicles, depending on weather
conditions. Jones said the team was optimistic that they would
be able to use the helicopters, though he was not certain.

The samples will be flown to the Johnson Space Center in
Houston early next week.