Proposed Mission Will Return Sample from Near-Earth Object (Forwarded)

Bill Steigerwald
NASA Goddard Space Flight Center, Greenbelt, Md. March 9, 2007

Lori Stiles
University of Arizona, Tuscon, AZ

Proposed Mission Will Return Sample from Near-Earth Object

A menacing lump of rock and dust in space called 10195 (1999 RQ36) would
barely be noticed except for two crucial facts: First, "It's a treasure
trove of organic material, so it holds clues to how Earth formed and life
got started," said Joseph Nuth of NASA's Goddard Space Flight Center,
Greenbelt, Md. Second, it regularly crosses Earth's orbit, so it might
impact us someday.

Nuth is Project Scientist for the proposed OSIRIS mission, which will
"return a pristine sample of the scientifically priceless asteroid RQ36 to
Earth for in-depth study," said University of Arizona Lunar and Planetary
Laboratory (LPL) Director Michael Drake, Principal Investigator for the
proposed mission. The mission will be the first to return a sample of an
asteroid to Earth. NASA Goddard is managing the project. Lockheed Martin
is building the flight system, the sampling mechanism, and the sample
return capsule. Lockheed Martin is also performing spacecraft operations.

The OSIRIS team recently won a $1.2 million award from NASA to develop a
more detailed engineering study of how the mission will accomplish its
scientific objectives. OSIRIS will launch in 2011, acquire a sample of
RQ36 in 2013, and return it to Earth in 2017.

OSIRIS is both a mythological figure and an acronym. "O" stands for the
scientific theme, origins. "SI" is for spectral interpretation, or taking
images of the NEO at wavelengths that will reveal its composition. "RI,"
or resource identification, is surveying the asteroid for such useful
resources as water and metals. "S" stands for security, learning how to
predict the detailed motion of Earth-approaching asteroids.

"OSIRIS of Egyptian mythology is the god of life and fertility, the god
who taught Egyptians agriculture," said Dante Lauretta, OSIRIS Deputy
Principal Investigator, also with the University of Arizona. "There's an
analogy to the proposed 21st century space mission. We're looking at the
kind of object that we think brought life to Earth; that is, objects that
seeded Earth with early biomolecules, the precursors of life."

Returning a sample to Earth will allow for a much more comprehensive study
of the NEO, according to the team. "The equipment in my lab is small,
merely desk-sized, but that's not easy to fly. Let alone the enormous
synchrotrons, which dwarf cars and are impossible to fly," said Jason
Dworkin, also of NASA Goddard, who is the Deputy Project Scientist and a
Co-Investigator on OSIRIS. "Furthermore, there are also a lot of steps to
prepare a sample. That would all have to be automated and work perfectly
on a spacecraft."

"Also, you can't respond to surprises with the limited equipment on board
a spacecraft," added Nuth. "About thirty years ago, the Viking landers
scooped up a sample of Martian dirt and tested it for signs of microscopic
life. The results were contradictory, and ever since then, there's been a
controversy over whether there really was life or whether it was just some
kind of exotic chemical reaction. If instead we were able to return
samples to Earth, we could have tested the sample in other ways. And when
technology improves, we just take samples out and test with the latest
equipment. That's what we'll be able to do with the sample returned by
OSIRIS."

OSIRIS samples will be available to the world-wide community, so people
with diverse skills and techniques can offer unique insights. "The
Stardust mission returned samples of comet Wild 2 with a total weight of
just a tenth of a milligram, but it is enough to be analyzed by
researchers all over the world," said Dworkin. "OSIRIS will return 150
grams -- about five ounces. We'll take it apart almost atom by atom. It
will keep a lot of people busy for a long time."

The mission will also help to better track the orbits of asteroids that
might hit Earth by accurately measuring the "Yarkovsky effect" for the
first time. The Yarkovsky effect is a small push on an asteroid that
happens when the asteroid absorbs sunlight and emits heat. The small push
adds up over time, and it is uneven due to an asteroid's various surface
materials, wobble, and rotation. There's no sure way to predict an
Earth-approaching asteroid's orbit unless you can factor in how the
Yarkovsky effect will change that orbit, according to the team. "It's like
trying to make a complex, banking shot in a game of pool with someone
shaking the table and kicking the legs," said Nuth.

RQ36 is roughly 580 meters in diameter, or about two-fifths of a mile. It
orbits between about 83 million and 126 million miles from the sun,
swinging within about 280,000 miles of Earth orbit, or roughly 40,000
miles more distant than the moon. The International Astronomical Union's
Minor Planet Center has officially classified RQ36 as a "potentially
hazardous asteroid."

"It doesn't present any near-term hazard, but the small Yarkovsky push
over hundreds of orbits may eventually be enough to cause an 'oops'," said
Nuth.

The OSIRIS proposal was among approximately two dozen submitted in
response to NASA's Discovery Program 2006 Announcement of Opportunity in
April. NASA also selected two other proposed new Discovery-class missions,
and three more Discovery-class proposals that would make use of existing
NASA spacecraft, for concept development funding. NASA may select one or
more investigations to continue into a development effort after detailed
review of the concept studies. Decisions about which mission concepts will
proceed to development are expected in late 2007.

IMAGE CAPTION:
[http://www.nasa.gov/centers/goddard/...iris_lgweb.jpg
(40KB)]
This is an artist's concept of the OSIRIS spacecraft taking a sample of
asteroid RQ36. Credit: NASA/U. of Arizona