Astronomy - February 2014

58 ASTRONOMY t FEBRUARY 2014

such bodies — the Stardust and Hayabusa
missions, respectively. Stardust was a NASA
Discovery class mission launched February
7, 1999. It encountered samples from Comet
81P/Wild in January 2004.
As the spacecraft f lew through the com-
et’s coma, several thousand dust particles
embedded themselves in a specially
designed collection tray containing 124
silica aerogel blocks, each measuring about
1.6 by 0.8 by 1.2 inches (4 by 2 by 3 centi-
meters). Stardust approached within 149
miles (240km) of the comet’s surface.
Remote control moved the collection
tray into a sample return capsule (SRC),
and Stardust headed toward Earth. On
close approach to our world in January
2006, the SRC separated from the space-
craft. It entered the atmosphere faster than
any human-made object on record, slowing

from a speed of nearly 28,600 mph (46,000

km/h) to about 10 mph (16 km/h) in only

13 minutes before parachuting into the U.S.

Air Force Utah Test and Training Range.

Two days later, workers transported the

SRC to the curation facilities at the Johnson

Space Center. Here, the collection tray sits

in the Stardust Laboratory, a specially

designed clean room.

The particles from the comet’s coma,

most of which are a fraction of the width of

a human hair, hit the aerogel at about 3.7

miles per second (6 km/s), slowed down,

and stopped at the end of carrot-shaped

tracks. These tracks are visible through a

microscope, and some are large enough to

see with the naked eye.

Scientists use these tracks to find the

tiny cometary particles in the nearly trans-

parent aerogel. They also developed precise

micro-tools for cutting a small wedge out of

the part of the aerogel that includes a par-

ticle. Using an instrument called a micro-

tome, they then can cut each particle into

hundreds of slices for detailed composi-

tional and textural studies.

One of the most significant findings

from the Stardust mission has been the dis-

covery of some particles with minerals that

formed at high temperatures in the inner

solar nebula. Scientists think comets

assembled in the cold outer reaches far

from the Sun. The finding suggests that the

solar system was a dynamic and turbulent

environment with large-scale mixing of

components that formed in both regions.

The Hayabusa mission

The other key mission came in 2003 when

the Japanese Aerospace Exploration Agency

On January 15, 2006, the Stardust sample return capsule separated from the spacecraft and streaked through Earth’s atmosphere before parachuting into the
Utah Test and Training Range in the early morning hours. Searchers found the Stardust sample return capsule (inset) lying on the ground soon after it landed.
The pod measures approximately 32 inches across by 20 inches high (0.8 by 0.5 meter).

As Japan’s Hayabusa spacecraft re-entered Earth’s atmosphere over Australia on June 13, 2010, it broke up (left). The spacecraft’s sample return capsule is the
small dot at lower right. Mission team members (center) recovered the capsule after it fell near the Woomera Test Facility in South Australia. The Planetary
Sample Curation Facility at Sagamihara, Kanagawa, Japan (right), is a specially built facility for handling and storing samples of the asteroid Itokawa.

Capsule