It seems years ago – November 29, 2005, to be exact – since a Japanese spacecraft named Hayabusa touched down on a small asteroid in the hope of grabbing samples of its dusty surface and returning them to Earth. Had the mission gone according to plan, the precious bits from asteroid 25143 Itokawa would have reached waiting scientists in June 2007.
But the flight of Hayabusa, Japanese for “falcon,” has been anything but nominal. In fact, it’s been more of a train wreck.
The craft was nearly lost during its grab-and-go encounter due to a series of malfunctions that should have doomed the spacecraft. But it hung on, despite suffering a massive fuel leak, battery failure, and being incommunicado for two months. Then its attitude-control system failed. The loss of three of its four xenon-powered engines meant it would take three extra years to get the crippled craft home, nursed every step of the way by its dedicated team of engineers.
Well, folks, Hayabusa is almost home. Late word from project manager Jun’ichiro Kawaguchi is that the sole remaining engine was commanded to shut down on March 27th, having gently accelerated the craft by 400 metres per second over the past year and nudged it onto a trajectory that will pass within several thousand kilometres of Earth. “What is left is a series of trajectory corrections,” Kawaguchi explains, “and the project team is finalizing the preparations for them.”
Barring an eleventh-hour setback, in mid-June a small 18-kilogram descent capsule will separate from the main spacecraft and slam into the atmosphere over south-central Australia. The larger craft will then manoeuvre to avoid Earth. Streaking through the darkness at 12.2 kilometres per second, the capsule should parachute to the ground somewhere along a target zone, measuring 100 by 15 km, in the remote Woomera Test Range.
After whisking it back to a clean room at the Japan Aerospace Exploration Agency (JAXA), scientists will carefully open the 40-cm capsule to learn, finally, whether it contains any asteroidal bits. It’s hardly a sure thing – despite sitting on Itokawa’s surface for 30 minutes, Hayabusa failed to fire two small tantalum pellets designed to kick surface material into a collection cone.
Hayabusa’s successful return would be a big deal in Japan, and plans for the welcome-home party are well under way. Kawaguchi has been careful not to divulge the exact date publicly, pending the engine shutdown and a sign-off from Australian authorities. “It is not at the beginning of June, and it is not at the end of June,” he teases. JAXA has produced an informative 21-minute video about the mission, in English, that you can view here. There’s even a dramatic movie treatment: Hayabusa: Back to the Earth.
Because spacecraft rarely come down through the atmosphere so fast – Earth-orbiting satellites fall in about a third slower – there’s plenty of scientific interest in the re-entry itself. The capsule should create an artificial fireball beginning at an altitude of about 200 km and hit a peak brightness of magnitude -6.7 (several times brighter than Venus) before deploying its parachute.
For the past year, meteor specialist Peter Jenniskens of the SETI Institute in California has been organising an international team to observe the capsule’s arrival from an instrument-packed DC-8 jet flying near the recovery zone. Jenniskens mounted a similar effort for the return of the Stardust sample capsule in January 2006.
Will Hayabusa, despite all its problems, make it back to Earth? Will the capsule contain hard-won bits of asteroid Itokawa? Will Kawaguchi and his team get a ticker-tape parade through downtown Tokyo? Stay tuned for the final chapter of this remarkable mission!
Courtesy of Sky and Telescope magazine
Some more info here.
Spacecraft to deliver asteroid sample over Australia
TOMORROW night at about midnight, a spacecraft will shoot across the northwest border of Australia, drop a saucer-shaped capsule to Earth above Woomera, then race on at 12km a second to burn up in the atmosphere.
If all goes well, Australians along the trajectory of Japan’s Hayabusa, or peregrine falcon, spacecraft may spot it, said Sydney Observatory astronomer Nick Lomb.
“I imagine it will look like a bright meteor or shooting star,” he said, adding that Hayabusa should be visible for up to 450km on either side of its flight path.
More distant space fans can follow Hayabusa’s re-entry live, as scientists aboard NASA’s DC-8 Airborne Laboratory will chase its progress, sending a video feed via the INMARSAT uplink, and by internet after landing in the Woomera Prohibited Area near Glendambo, South Australia.
Launched on May 9, 2003, by the Japan Aerospace Exploration Agency (JAXA), Hayabusa’s mission was to travel about 2 billion km to the asteroid Itokawa, named after Japanese rocket scientist Hideo Itokawa.
In November 2005, Hayabusa made two successful landings to collect samples of Itokawa’s rocky surface. But its return was delayed for three years after fuel leaks in one of its chemical engines, then deterioration of its next-generation ion engines and communication problems.
Australian National University geochemist Trevor Ireland will join JAXA and NASA scientists during retrieval of the Hayabusa’s sample return capsule.
“It will be a major scientific prize,” Professor Ireland said. “It will be only the fourth sample return mission from outside Earth.”
The first samples were collected on the moon by Apollo astronauts and Russian cosmonauts, the second were solar wind particles collected during the Genesis mission in 2004, and most recently cometary dust samples returned by the Stardust spacecraft in 2006.
If Hayabusa’s capsule contains a few grams of material, even a grain, it will provide new details about the early history of the solar system, said NASA stratospheric dust expert Michael Zolensky.
“You can do incredible things with a sample that small,” Dr Zolensky said, noting that a “microscopic grain” could be cut into 100 or more slices.
Scientists could use the slices to reveal Itokawa’s chemical characteristics and mineralogical composition, both key to how and when it was formed