Inside the daring mission to bring pieces of ancient asteroid Ryugu back to Earth

In a gray camouflage tee and blue denim jeans, Masaki Fujimoto is dressed all too casually for a man about to make history. Queen’s Don’t Stop Me Now has been playing on repeat, in his head, for weeks. One line is particularly prophetic for the 56-year-old astrophysicist.

“I’m burning through the sky…”

It’s less than 48 hours from when a 16-inch-wide steel capsule will do just that, rocketing through the atmosphere before unfurling a parachute and gently landing in a sparsely populated area of the Australian outback. Locked inside is ancient cargo — pieces of a 4.6 billion-year-old near-Earth asteroid collected by Hayabusa2, the star spacecraft in the Japan Aerospace Exploration Agency fleet.

Over the past six years, Hayabusa2 has achieved an extraordinary engineering triumph, filled with exhilarating firsts. It visited the dark, enigmatic Ryugu, an asteroid orbiting between Earth and Mars, and landed hopping robots on its surface. It imaged the exterior of the asteroid in exquisite detail and blasted a hole in its side with a copper cannonball. But the mission’s masterstroke was sampling material from that wound it created in Ryugu’s side — the first time a spacecraft has snatched rock from beneath an asteroid’s surface. 

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The spacecraft’s achievements are some of the most valuable in the history of deep space exploration, akin to NASA’s feats of landing rovers on Mars or exploring Pluto and its moons up close. On a smaller budget than NASA’s, with a much smaller team, Japan wrote its way into space history. Yet for the mission to be considered a complete success, the team must land Hayabusa2’s sample capsule safely back on solid ground.

Fujimoto, the deputy director general of JAXA’s Institute of Space and Aeronautical Science, is responsible for bringing the spacecraft and its samples home. Trained as a theoretical physicist, he’s leading the sample capsule recovery from the ground in Australia, overseeing nearly 80 scientists and engineers who have descended on the tumbledown outback town of Woomera. 

Flat, ochre plains stretch for miles. The closest town is two hours away. Few places are as desolate, and yet as accessible, as Woomera. 

The perfect place to drop an asteroid sample.

Hayabusa2’s journey has been near flawless to date, but JAXA’s runsheet never included “global pandemic.” Travel restrictions forced Fujimoto to rewrite sample retrieval plans in April 2020, cutting the recovery team in half and mandating a quarantine period of 21 days for team members traveling to Woomera. 

“It’s been a very intense eight months,” he says.

Editors’ note: This piece was originally published March 17, 2021. It has been republished on June 30 to coincide with Asteroid Day

On Dec. 4, 2020, just over a day before the sample’s scheduled return, Fujimoto fronts a press conference in Woomera, discussing the mission. Over the past three weeks, he’s hardly slept, but the only hint he’s tired is a cappuccino he cradles in his hand. He takes a sip. “I don’t think you can sleep in my position,” he tells me.

Despite his scientific sensibilities, Fujimoto believes fate is guiding the asteroid sample back to Earth. Strange coincidences throughout the vehicle’s six-year journey, he says, demonstrate this theory. Signs the mission is destined for success. 

The strangest of them all? On the night Hayabusa2’s sample capsule comes careening back to Earth, the Woomera Theatre, which has 500 seats and only one screen, is scheduled to show Queen biopic Bohemian Rhapsody. 

Exterior of the Woomera Theatre and, nearby, a movie poster for Bohemian Rhapsody.

The Woomera Theatre was set to play the Rami Malek-led Queen biopic, Bohemian Rhapsody, just hours before the sample capsule’s return.

Jackson Ryan/CNET

I. Keep Yourself Alive

Hayabusa2’s journey began 18 years ago with its predecessor, Hayabusa. 

The original 2003 mission put JAXA on the world stage, highlighting its engineering prowess. The first asteroid sample-return mission ever attempted, Hayabusa was designed to travel to an irregular, slug-shaped body known as 4660 Nereus, briefly touch down on its surface, steal away pieces of rock and ferry them back to Earth. 

The thinking back then, Fujimoto says, was to perform a feat of cosmic exploration NASA “would never dare” attempt, but the mission was plagued by problems almost as soon as it launched. 

“Hayabusa was a very challenging mission,” says Saiki Takanao, a mission engineer with JAXA. Its initial launch was delayed, forcing it to change targets to a bean-shaped asteroid named Itokawa. Then, during its cruise phase, it was hit by a massive solar flare — during a year of hellacious sun activity — disrupting its solar cells and decreasing the efficiency of its engines. It arrived at Itokawa three months behind schedule, and an attempted landing proved disastrous when a leak in the spacecraft’s thrusters reduced its ability to manage its orientation. It spun out of control. Communication was lost. 

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The team tried everything to locate the spacecraft. Junichiro Kawaguchi, the JAXA scientist who led the mission, even remembers visiting a small shrine, about five minutes walk from mission control, to ask for divine intervention. “Parents used to go to that shrine and pray their kid will come back,” Fujimoto says. 

Within weeks, the spacecraft pinged home. 

Hayabusa cheated death, but two of its engines were busted. Data showed the spacecraft only glanced the surface of the asteroid and likely contained mere flecks of dust within the sample capsule. Clever engineering workarounds allowed the team to set course for Earth, but Hayabusa was headed for more misery. A third engine blew out on the way back.

It limped home three years late, ejected its sample capsule and slammed into the atmosphere. In its final moments, the spacecraft showered the skies over Woomera with thousands of fireballs. As the final sparks winked out, Hayabusa’s mission came to a close. JAXA was not deterred by the original mission’s problems, and plans for a sequel were already in motion. It would use Hayabusa as a starting point and visit an entirely new asteroid.

But if it was to succeed, the team would have to improve its futuristic propulsion system in just three years, half the time it had to build Hayabusa. 

II. Under Pressure

Ion engines appear to function as if by magic.

The complex wizardry that makes them work is officially known as “electric propulsion” and involves a mix of magnetic and electric fields, gas and plasma. But boil it down, and ion engines are essentially particle pinball machines strapped to the back of a spacecraft. Inside them, electrons collide with atoms to produce charged ions. These ions are pushed out of the engine at speed by a sustained electric field at the rear, delivering a very small amount of thrust. 

Unlike typical chemical engines, which use extreme amounts of fuel rapidly and deliver huge amounts of thrust in one big, violent burst, ion engines are designed to be used for tens of thousands of hours. They require a comparatively tiny amount of fuel. “If you need to do it fast, you use a chemical rocket,” says Nathan Brown, an aerospace engineer at the Georgia Institute of Technology. “If you want to do it cheaply and efficiently, you use electric propulsion.”

JAXA’s only option with the Hayabusa missions was cheap and efficient. The agency operates on a budget roughly 5% of NASA’s, with a team about one-tenth the size. The budget for Hayabusa2 is about one-third of NASA’s for Osiris-Rex, an asteroid sample return mission the US agency launched in 2016. 

Though troubled, Hayabusa’s ion engines, designed and built in house by now-ISAS director general Hitoshi Kuninaka and his team, provided a solid foundation for Hayabusa2. But the team was constantly under pressure. “We were behind schedule a lot of the time,” says Ryudo Tsukizaki, a JAXA engineer.

Hayabusa2’s engines would need to help carry the spacecraft 1.75 billion miles to reach its destination. Kazutaka Nishiyama, a JAXA engineer who led the ion engine team, says it was critical to increase the lifespan of the engines. Three of Hayabusa’s engines failed at around 10,000 hours — 14 months — due to a critical component of the engine known as a “neutralizer.” Tinkering with the neutralizer provided the necessary improvements to the lifespan. 

At the ISAS laboratory in Japan, an Earth-bound twin of the Hayabusa2’s ion engine system is still being tested in a vacuum chamber today. When I talked to Nishiyama in October 2020, it had been switched on for 67,000 hours (seven and a half years). The early results of the test imbued the team with renewed conviction. 

Hayabusa2 launched on Dec. 3, 2014, from Tanegashima Space Center in Japan. By the time launch day rolled around, the stress and pressure of ion engine development had all but faded. “We were very confident,” says JAXA engineer Tsukizaki. For large parts of the mission, it cruised through the dark, lit by the aqua glow of its ion thrusters and dim light from the sun. Unlike its predecessor, it had a faultless sojourn, marked only by an occasional wave of X-rays washing over the spacecraft and periodically stopping the engines. 

But when Hayabusa2 left Earth, it was headed to an asteroid without an official name. Its provisional designation, 1999 JU3, merely referred to the date and time of its discovery. The rock was a mystery.

“The asteroid is a new world,” says Yuichi Tsuda, the project manager of Hayabusa2. “Before getting there, we do not know anything about it.” 

In 2015, the team at JAXA put out a call to the Japanese public to name the rock. From 7,336 entries, the selection committee settled on one.

Ryugu.

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III. The Dragon Palace

According to an ancient Japanese folktale, some 1,500 years ago, the fisherman Urashima Taro pushed his boat out into the Sea of Japan, under a soft blue sky. Taro drifted on the waves for hours, waiting to hook a red bream or bonito. The other villagers thought of him as kindhearted but most believed him lazy and luckless. He often returned to shore empty-handed as the summer sun sank beneath the horizon.

But on this summer morning, Taro’s fortunes reversed. His rod stirred, clattering against the boat. A catch! Excitedly, Taro drew the line, but as he reeled in the prize, he realized it wasn’t a fish he had hooked. It was a turtle.

Taro delicately removed the line from the creature’s mouth and returned it to the sea with a gentle prayer. He placed his hands behind his head and lay down, dozing off, the sun’s heat prickling his skin. 

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As he slept, a beautiful woman rose out of the sea. She moved as if carried by the wind, her long, black hair caught in a zephyr, crimson and blue robes trailing her in waves. Gliding toward the boat, she woke Taro with a soft touch, whispering to him.

“Don’t be afraid,” she said. “I am Princess Otohime. Today you showed me great kindness when you set me free from your hook. My father, the Dragon King of the Sea, sent me to you. He wishes for you to attend his palace beneath the waves. There, you may take me as your wife if you wish and we will live happily forever.”

Urashima Taro agreed to go with the Princess to the Dragon Palace, Ryugu, an ornate castle made of coral and sand. There he met the Dragon King and married Otohime. In the enchanted land, he lived in an endless summer for three years.

By the fourth year, he grew restless. He’d fallen in love with Otohime, but began to worry about his elderly parents, alone at home. When he informed Otohime of his desire to return to them, she was crestfallen. She attempted to dissuade Taro from leaving but ultimately agreed to let him go, offering him a small treasure box, a tamatebako, tied with a silk string.

“If you wish to see me again, you must never open this,” she told him. Taro nodded, agreeing he would never so much as loosen the string. At this, he was whisked from the castle under the sea back to his boat, bobbing in the Sea of Japan. The sun was descending. He glided back into shore.

As he disembarked and stood upon the beach, his heart filled with doubt. 

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The village had changed. The Shinto temple he visited as a boy had been rebuilt with a new facade. The mountainside had been cleared of its trees. There were more houses than he remembered. The fisherfolk glanced skeptically at Taro as he bounced between houses, hoping to find his home. But he could not. Finally, an old man with a walking stick came by, and Taro asked where he might find the home of the Urashima family.

The old man laughed. “Do you not know the story of Urashima Taro?” he started. “The fisherman disappeared 400 years ago. Everybody says he drowned. His family is buried in the old graveyard.”

Taro rushed to the graveyard. The tombstones of his family…