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Japan’s Journey to an Asteroid Ends With a Hunt in Australia’s Outback
The Hayabusa2 mission cements Japan’s role in exploring the solar system, but finding its asteroid cargo presents one last challenge.
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Japan’s space agency is nearing the end of a journey of discovery that aims to shed light on the earliest eons of the solar system and possibly provide clues about the origins of life on Earth.
But first, it is going to have to go on a scavenger hunt in the Australian outback.
This weekend, bits of an asteroid will land in a barren region near Woomera, South Australia. These are being ferried to Earth by Hayabusa2, a robotic space probe launched by JAXA, Japan’s space agency, in 2014 to explore an asteroid named Ryugu, a dark, carbon-rich rock a bit more than half a mile wide.
The success of the mission and the science it produces will raise Japan’s status as a central player in deep space exploration, together with NASA, the European Space Agency and Russia. JAXA currently has a spacecraft in orbit around Venus studying that planet’s hellish climate and is collaborating with the Europeans on a mission that is on its way to Mercury.
In the coming years, Japan plans to bring back rocks from Phobos, a moon of Mars, and contribute to NASA’s Artemis program to send astronauts to Earth’s moon.
But the immediate challenge will be searching in darkness for a 16-inch-wide capsule containing the asteroid samples somewhere amid hundreds of square miles in a region 280 miles north of Adelaide, the nearest large city.
“It’s really in the middle of nowhere,” said Shogo Tachibana, the principal investigator in charge of the analysis of the Hayabusa2 samples. He is part of a team of more than 70 people from Japan who have arrived in Woomera for recovery of the capsule. The area, used by the Australian military for testing, provides a wide open space that is ideal for the return of an interplanetary probe.
The small return capsule separated from the main spacecraft about 12 hours before the scheduled landing, when it was about 125,000 miles from Earth. JAXA will broadcast live coverage of the capsule’s landing beginning at 11:30 a.m. Eastern time on Saturday. (It will be pre-dawn hours on Sunday in Australia.)
The capsule is expected to hit the ground a few minutes before noon.
In an interview, Makoto Yoshikawa, the mission manager, said there is an uncertainty of about 10 kilometers, or about six miles, in pinpointing where the capsule will re-enter the atmosphere. At an altitude of six miles, the capsule will release a parachute, and where it will drift as it descends will add to the uncertainty.
“The landing place depends on the wind on that day,” Dr. Yoshikawa said. The area that searchers might have to cover could stretch some 60 miles, he said.
The trail of the fireball of superheated air created by the re-entering capsule will help guide the recovery team, as will the capsule’s radio beacon. The task will become much more difficult if the beacon fails or if the parachute fails to deploy.
There is a bit of a rush, too. The team hopes to recover the capsule, perform initial analysis and whisk it back to Japan within 100 hours. Even though the capsule is sealed, the worry is that Earth air will slowly leak in. “There is no perfect sealing,” Dr. Tachibana said.
Once the capsule is found, a helicopter will take it to a laboratory that has been set up at the Australian air force base at Woomera. There an instrument will extract any gases within the capsule that may have been released by the asteroid rocks as they were shaken and broken during re-entry. Dr. Yoshikawa said the scientists would also like to see if they can detect any solar wind particles of helium that slammed into the asteroid and became embedded in the rocks.
The gases would also reassure the scientists that Hayabusa2 did indeed successfully collect samples from Ryugu. A minimum of 0.1 grams, or less than 1/280th of an ounce, is needed to declare success. The hope is the spacecraft brought back several grams.
In Japan, the Hayabusa2 team will begin analysis of the Ryugu samples. In about a year, some of the samples will be shared with other scientists for additional study.
To gather these samples, Hayabusa2 arrived at the asteroid in June 2018. It executed a series of investigations, each of escalating technical complexity. It dropped probes to the surface of Ryugu, blasted a hole in the asteroid to peer at what lies beneath and twice descended to the surface to grab small pieces of the asteroid, an operation that proved much more challenging than expected because of the many boulders on the surface.
Small worlds like Ryugu used to be of little interest to planetary scientists who focused on studying planets, said Masaki Fujimoto, deputy director general of the Institute of Space and Astronautical Science, part of JAXA. “Minor bodies, who cares?” he said. “But if you are serious about the formation of planetary systems, small bodies actually matter.”
Studying water trapped in minerals from Ryugu could give hints if the water in Earth’s oceans came from asteroids, and if carbon-based molecules could have seeded the building blocks for life.
Part of the Ryugu samples will go to NASA, which is bringing back some rocks and soil from another asteroid with its OSIRIS-REX mission. The OSIRIS-REX space probe has been studying a smaller carbon-rich asteroid named Bennu and it will start back to Earth next spring, dropping off its rock samples in September 2023.
Ryugu and Bennu turned out to be surprisingly similar in some ways, both looking like spinning tops and with surfaces covered with boulders, but different in other ways. The rocks on Ryugu appear to contain much less water, for one. The significance of the similarities and differences will not become clear until after scientists study the rocks in more detail.
“When the OSIRIS-REX sample comes back, we will have lessons learned from the Hayabusa2 mission,” said Harold C. Connolly Jr., a geology professor at Rowan University in New Jersey and the mission sample scientist for OSIRIS-REX. “The similarities and differences are absolutely fascinating.”
Dr. Connolly hopes to go to Japan next summer to take part in analyzing the Ryugu samples.
Hayabusa2 is not Japan’s first planetary mission. Indeed, its name points to the existence of Hayabusa, an earlier mission that brought back samples from another asteroid, Itokawa. But that mission, which launched in 2003 and returned in 2010, faced major technical problems. So did JAXA’s Akatsuki spacecraft, currently in orbit around Venus, which the Japanese agency managed to restore to a scientific mission after years of difficulty. A Japanese mission to Mars also failed in 2003.
By contrast, operations of Hayabusa2 have gone almost flawlessly, even though it retains the same general design as its predecessor. “Actually, there are no big issues,” Dr. Yoshikawa, the mission manager, said. “Of course, small ones.”
He said the team studied in detail the failures on Hayabusa and made changes as needed, and also conducted numerous rehearsals to try to anticipate any contingencies it might encounter.
The Japanese missions generally operate on smaller budgets than NASA’s and thus often carry fewer instruments. Hayabusa2’s cost is less than $300 million while OSIRIS-REX’s price will run about $1 billion.
Dropping off the Ryugu samples is not the end of the Hayabusa2 mission. After releasing the return capsule, the main spacecraft shifted course to avoid a collision with Earth, missing by 125 miles. It will now travel to another asteroid, a tiny one designated 1998 KY26 that is only 100 feet in diameter but spinning rapidly, completing one rotation in less than 11 minutes.
Hayabusa2 will use two flybys of Earth to fling itself toward KY26, finally arriving in 2031. It will conduct some astronomical experiments during its extended deep space journey, and the spacecraft still carries one last projectile that it may use to test that space rock’s surface.
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