Artist's conception of the Hayabusa
spacecraft deploying one of the surface target markers that will be used
to guide the spacecraft's descent to the surface of asteroid Itokawa.
Hayabusa's Contributions Toward Understanding the Earth's Neighborhood
August 11, 2005
Beginning in early September 2005, the Japanese Hayabusa spacecraft will rendezvous
with near-Earth asteroid (25143) Itokawa. Itokawa, a 600 meter sized,
potato-shaped asteroid, is named after Hideo Itokawa, a Japanese rocket
pioneer. Although the primary objectives of the Hayabusa mission are
to test new technologies, the mission will also provide a wealth of scientific
returns. For the three month period from September through November 2005,
the science instruments on board the Hayabusa spacecraft will undertake
an intensive study of near-Earth asteroid Itokawa. After closely observing
the asteroid for several weeks, a few pellets will be fired from the spacecraft
at close range into the asteroid's surface and about a gram of the pellet's
impact ejecta will be collected into a sample capsule. This capsule will
then be brought back to Earth and parachuted into the Australia outback
in June 2007 so that some of the asteroid's surface minerals can be
studied in Earth-based laboratories. This will be the first asteroid
sample return mission.
After the successful launch of the spacecraft
on May 9, 2003 from the Japanese Kagoshima Launch site, the mission name
was changed from MUSES-C to Hayabusa.
Hayabusa, which is Japanese for
"falcon," will act much like its namesake, descending to the asteroid's
surface, capturing its prey and returning it to Earth. While the scientific
knowledge of near-Earth asteroids will be significantly advanced by the
Hayabusa mission, the primary goals are to test four advanced technology
systems: the electric propulsion (ion drive) engines; an autonomous navigation
system; the sample collection system; and the sample capsule that re-enters
the Earth's atmosphere.
A year after launch, on May 19, 2004, the
spacecraft returned to Earth and made a close approach (altitude = 3725
km), thereby gaining the extra velocity it needed to reach the near-Earth
asteroid Itokawa. During the Earth swing-by, the spacecraft also took
images of the Earth and moon to test and calibrate the on board camera
called AMICA (Asteroid Multi-band Imaging Camera). These Earth and lunar
images can be viewed at:
Because the efficiency of the solar panels were slightly degraded as
a result of a solar flare in late 2003, the ion engines no longer receive
quite as much electricity as they should so the spacecraft's arrival
at the asteroid was delayed from mid-summer until September of 2005.
Upon arriving at the asteroid, the Hayabusa spacecraft will spend about three
months hovering above the asteroid with its high gain antenna pointed
toward Earth and its science instruments pointed toward the asteroid's
surface. Using the spacecraft camera, the entire surface of the asteroid
will be mapped so that its size, shape and volume can be determined.
The Hayabusa spacecraft carries infrared and X-ray spectrometers that
will identify the asteroid's most common minerals and chemical constituents.
In mid-September, the spacecraft will evolve down to its so-called "gate
position," 20 kilometers above the asteroid's surface, where it will
begin the global mapping of the surface features and determine its surface
composition. Toward the end of September, the spacecraft will move to
its "home position," which is only seven kilometers above the surface.
At this home position, a more detailed surface map will be generated
and the surface composition differences will be examined as the asteroid
rotates underneath the hovering spacecraft.
In the second half of November, the spacecraft
will collect up to three surface samples as its sample horn captures small
pieces of the asteroid ejected when tantalum pellets are fired into its
surface at 300 meters per second. With these surface samples tucked safely
into the spacecraft's sample capsule, the spacecraft will return to
Earth, arriving in June 2007, and the sample capsule will parachute to
the ground in Australia. The samples will be analyzed in various laboratories
to study their detailed chemical composition and determine which meteorite
examples in Earth-based collections provide the best match for Itokawa's
particular composition. Once this question is answered, then future Earth
based observations can be used to identify the likely minerals in other
asteroids that share the same spectral characteristics as Itokawa.
Artist's conception of the Hayabusa spacecraft and the Minerva surface
During the first descent to fire a pellet into the surface, a small
coffee-can-sized surface hopper, called MINERVA, will be dropped slowly
onto the asteroid's surface. For one to two days it will slowly leap
about the asteroid taking surface temperature measurements and high-resolution
images with each of its three miniature cameras.
will address each of three major issues concerning asteroids:
1.) their role as the building blocks of the solar system, 2.) their
potential for impacting Earth and 3.) their future use as raw materials
for building space structures.
- The scientific interest in asteroids is due
largely to their status as the remnant debris from the inner solar system
formation process that occurred some 4.6 billion years ago. Since the
chemical compositions of asteroids have remained relatively unchanged
since their formation, knowledge of their elemental makeup would provide
an understanding of the chemical mix from which the inner planets, including
- From time to time, near-Earth asteroids collide
with Earth. Should one of them be found upon an Earth threatening trajectory,
scientists would need to understand its composition and structure before
a successful strategy could be undertaken to deflect the object away from
- Some of the near-Earth asteroids that are potentially the
most hazardous because they can closely approach the Earth are also the
objects that could be most easily reached and exploited for raw materials.
The minerals, metals and water ices on near-Earth asteroids and comets could be
used to manufacture the space structures and rocket fuel that will be
required to explore and colonize our solar system in the 21st century.
We need to examine the chemical composition of some of these objects
to understand which among them are richest in mineral wealth and other
The Hayabusa asteroid sample return mission is the next
giant step forward in understanding the role of near-Earth asteroids in
the origin of the solar system, their potential threat to Earth and the
future use of their raw materials to expand the human presence beyond
Hayabusa Project (JAXA main site)
SPACE NEWS (JAXA) -- Hayabusa acquired images of the earth and the moon.
Hayabusa Science Objectives
AMICA - Asteroid Multiband Imaging Camera
- Map surface morphology including surface features to one 1-m resolution
- Determine spin state, colors, size, shape, volume, and rotation characteristics
- Search for possible asteroid satellites and dust rings
- Establish a global map of surface features and colors
- Reveal history of impacts from other asteroid and comet fragments
- Determine optical parameters of regolith particles using polarization degree vs.
phase curve at large phase angles
- Map mineralogical composition of asteroid and identify rock types present
- Determine most likely meteorite analog for composition of asteroid
- Map mineralogical composition of asteroid and provide main evidence for rock types
present on surface at scales as small as 20 m
- Characterize surface heterogeneity
- Together with elemental composition measurements provided by (XRS) and color
imagery from camera, IR spectrometer will provide link between this asteroid and
a meteorite type
X-Ray Spectrometer (XRS)
- Map the major elemental composition of the surface as the asteroid rotates under
- Determine the major elemental composition at localized
areas during asteroid approach phases
- Measure surface composition accurately enough to establish relationship between
asteroids and meteorites and identify type of meteorite to which asteroid is linked
- Provide elemental abundance maps to investigate inhomogeneity of regolith
Sample Return Analysis
- Samples returned to Earth will provide a detailed and definitive elemental
composition analysis of the asteroid's surface materials and hence forge an
unambiguous link between the asteroid's composition and a meteorite type
- Provide accurate shape and mass determinations for asteroid
- Map asteroid's surface with a maximum resolution of about 1-meter