WWW.ASTRONOMY.COM 59(JAXA) launched Hayabusa, originally
called MUSES-C, to collect and return
samples from the small near-Earth asteroid
Itokawa. This minor planet belongs to the
second most common class (S type, stony).
The goal of the mission was to understand
its composition and formation history.
The Hayabusa spacecraft arrived at Ito-
kawa in September 2005 and spent 2½
months making remote observations of the
asteroid’s shape and composition. Follow-
ing these observations, JAXA scientists
intended the spacecraft to perform three
touch-and-go maneuvers during which a
gun was to fire and broken-off asteroid
chips were to be collected. But the gun
failed to fire on two attempts.
The collection mechanism did not per-
form as expected, and at the time research-
ers could not confirm whether sample
collection was successful. Despite a series of
subsequent communication and control
failures, JAXA engineers returned Haya-
busa to Earth in June 2010. They recovered
its sample capsule in the Woomera Prohib-
ited Area in South Australia.
Although the sampling mechanism (pri-
marily the gun) did not operate as scientists
intended, the sample canisters contained
thousands of tiny particles from Itokawa.
Scientists extracted these particles and ini-
tially examined them in a specially
designed laboratory in Sagamihara, Japan.
According to an agreement with NASA,
JAXA delivered 10 percent of the particles
to the Johnson Space Center.
Most of our current understanding of
asteroids comes from studying meteorite
samples that astronomers believe origi-
nated in asteroidal bodies. It has been dif-
ficult, however, to match the compositions
of the different kinds of meteorites with
those of the known types of asteroids
because processes, such as bombardment
by solar wind particles (“space weather-
ing”), change the way asteroid surfaces
appear in telescopic observations. The Ito-
kawa particles are the first samples from an
asteroid. What’s more, because of the
remote observations the spacecraft made
prior to sampling, researchers understand
the geologic context for these particles.
By studying these particles, we have
learned that S-type asteroids are similar in
composition to the most commonly found
meteorites, ordinary chondrites. More spe-
cifically, Itokawa appears to be most similar
to the low-iron variety of ordinary chon-
drites. So, studying these particles allows us
to better understand asteroids. In particu-
lar, it appears that Itokawa was originally
much larger but broke apart as a result ofimpacts; only a small fraction of the origi-
nal material reassembled.Small is indeed beautiful
Scientists can glean a tremendous amount
of information from the tiniest of extrater-
restrial samples. In fact, the smallest mate-
rials in NASA’s collections preserve the
oldest records of solar system history.
Technological advances in instrumenta-
tion are allowing researchers from around
the world to handle and study these tiny
fragments in fantastic detail. It all leads to
some amazing insights into the origin of
the solar system and possibly even how life
developed on our planet.THE STARDUST MISSION
1) Members of the Star-
dust mission team care-
fully opened the
sample return capsule
in a specially-built,
ultraclean curation lab-
oratory at NASA’s John-
son Space Center in
Houston. 2) The curato-
rial team examined and
documented the sur-
faces of the aerogel
blocks in the Stardust
collector tray using an
optical microscope. 3)
The tennis-racket-sized
collector on the Star-
dust mission contained
124 blocks of aerogel
and provided more
than 155 square inches
(1,000 square centime-
ters) of surface area to
capture cometary —
and possibly some
interstellar — dust
grains. 4) Science team
members examine the
aerogel collector array.1 2
3 4
This fragment is from the asteroid Itokawa.
The Japanese Aerospace Exploration Agency’s
Hayabusa spacecraft returned the approximately
50-micron long specimen to Earth in June 2010.