In July, Japanese scientists announced that they had found something inside Hayabusa’s 40cm-wide sample return capsule, but it was far from certain as to what that “something” was. Was it dusty contamination from reentry? Or was it precious asteroid dust, the very thing the sample return mission set out to capture?
Now we have an answer.
The trouble-plagued Hayabusa did return asteroid dust. In fact, 1,500 particles of the stuff have been recovered so far.
“This is a world first and it is a remarkable accomplishment that brought home material from a celestial body other than the moon,” Yoshiaki Takagu, Japanese science and technology minister, told a press conference announcing mission success.
On June 13, the Japanese mission came to a spectacular end. Slamming into the atmosphere after a 7-year round-trip, the spacecraft dazzled on re-entry, disintegrating and burning up over the Australian outback.
Before the fireworks however, the Hayabusa probe jettisoned a precious sample return capsule that reentered the atmosphere safely ahead of the doomed spacecraft to parachute to Earth.
Since that day, scientists have been patiently waiting to find out whether that capsule carried any precious cargo. And now, after six months of study, the Japanese space agency JAXA has confirmed everyone’s wildest dreams: Hayabusa successfully completed its mission and brought dust from the 400 meter-wide asteroid Itokawa home.
After analysis, JAXA researchers have found iron-rich olivine and pyroxene particles mostly less than 10 microns across (1/5th the width of a human hair). This confirms the particles are indeed of extraterrestrial origin and not contamination from an Earth-based source.
Also, the samples have little iron or nickel, consistent with our understanding of the composition of the small asteroid.
Itokawa is an S-type asteroid, something that has not only been observed from ground-based observatories, but now confirmed by analyzing samples direct from the asteroid’s surface. This provides priceless confirmation that our methods for classifying asteroids (or at least S-type asteroids) is accurate. You can’t beat grabbing samples direct from the asteroid you’re looking at from afar!
S-type asteroids are of a stony composition, and Itokawa is often referred to as a “rubble pile” due to the boulders, rocks and dust all stuck together by gravity (and possibly van der Waals forces).
This successful mission conclusion is of critical importance to not only science but also the well-being of our civilization.
Hayabusa has proven that we can send a probe to an asteroid, dock with it, overcome all the odds and return a sample of dust back to Earth. On a global scale, our understanding of asteroids has just been enhanced, helping us better understand these potentially hazardous space rocks, ultimately aiding our ability to deal with them should a “big one” be aimed right at us.
Images: The “rubble pile” asteroid Itokawa (top); tiny particles line the edge of a special spatula used to extract them from Hayabusa’s sample container (middle); artist’s impression of Hayabusa taking a sample from Itokawa (bottom). Credit: JAXA.
Source: Sky and Telescope