[meteorite-list] Asteroid Itokawa Sample Return

[Ron Baalke]

http://science.nasa.gov/science-news/science-at-nasa/2010/30dec_samplereturn/

Asteroid Itokawa Sample Return
NASA Science News

Dec. 29, 2010:  The Japanese Aerospace Exploration Agency's Hayabusa
spacecraft has brought home to Earth tiny pieces of an alien
world - asteroid Itokawa.

"It's an incredible feeling to have another world right in the palm of
your hand," says Mike Zolensky, Associate Curator for Interplanetary
Dust at the Johnson Space Center, and one of the three non-Japanese
members of the science team. "We're seeing for the first time, up close,
what an asteroid is actually made of!"

He has good reason to be excited. Asteroids formed at the dawn of our
solar system, so studying these samples can teach us how it formed and
evolved.

Hayabusa launched in 2003 and set out on a billion kilometer voyage to
Itokawa, arriving a little over two years later. In 2005, the spacecraft
performed a spectacular feat -- landed on the asteroid's surface^(1) .
The hope was to capture samples from the alien world.

But there was a problem. The projectiles set to blast up dust from the
surface failed to fire, leaving only the particles kicked up from
landing for collection. Did any asteroid dust made it into the
collection chamber?

Zolensky and other eager scientists, with eyes riveted skyward, watched
the answer plunge back into Earth's atmosphere at 27,000 miles per hour
on the night of June 13th, 2010. Hayabusa's main bus shattered over the
Australian outback during reentry, and the intact sample return capsule
drifted to Earth via parachute.

"We were mesmerized," says Zolensky. "As we waited for it to land, no
one even moved."

But the waiting was only just beginning. Because attempting retrieval of
the capsule in the dark was too dangerous, he spent a sleepless night
before getting a closer look.

"I was one of the first people to board the helicopter that flew to the
landing site the next morning. And I was the first person to walk up to
the capsule."

He had to stop within 10 feet of it. More waiting.

"I watched the retrieval team recover it. They wore face masks and
gloves and blue padded suits. They had to disable the unexploded
parachute release charges, and that was pretty nerve wracking. Then they
picked up the capsule oh so carefully and placed it in a box."

The precious cargo was flown via charter jet to Japan for analysis.
Guess who was waiting for it when it arrived?

"I was ready to work," says Zolensky, who along with fellow team member
Scott Sandford of NASA Ames Research Center had traveled to Japan for
the opening.

"The first results were disheartening. When we scanned the capsule with
a modified CAT scan, there appeared to be nothing inside."

Next, Japanese members of the team painstakingly dismantled the capsule,
piece by piece. "They had to use a micromanipulator to avoid
contamination, and the process took months."

More waiting.

"Once we got inside the capsule, we could see dust on the interior
walls. I thought to myself, 'we've got asteroid dust here!' But there
was still a possibility the contents could be contamination from launch
or reentry and landing."

The next step was to remove and analyze the particles -- another
agonizingly slow process, and more waiting.

"The particles are each smaller than the diameter of a human hair. We
finally used a Teflon spatula to sweep out a large number of tiny
particles."

Though most of the particles are still in the capsule, the team has
removed and analyzed 2000 of them with an electron microscope.

And?

"At least 1500 of them are from the asteroid! We're seeing pieces of
another world. It looks like a very primitive type asteroid. We'll tell
you more in March at the 2011 Lunar and Planetary Science Conference in
Houston."

This is only the third time ever that samples of a solid
extraterrestrial body have been brought back to Earth. The Apollo
astronauts and Soviet Luna robots were first - they brought us samples
of moondust. And NASA's Stardust spacecraft returned samples of comet
Wild 2 in 2006.

"The Japanese people are thrilled, and so are we. The emperor even
requested a personal tour of the capsule. This is their Apollo mission.
They're showing us all a new world!"


Author: Dauna Coulter
Editor: Dr. Tony Phillips
Credit: Science at NASA