Inside Japan’s daring 10-year mission to visit ancient asteroid Ryugu – CNET

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"

In less than 48 hours, 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.

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.

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.

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

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.

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.

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.

We were behind schedule a lot of the time.

JAXA engineer Ryudo Tsukizaki

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.

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.

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.

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 appeared decrepit and eaten by moss. A monument to his own death stood, crumbling, by their side. His parent's names were barely legible. At this, he believed himself to be the victim of some cruel illusion and returned to the beach, tamatebako in hand.

In desperation, he tore the silk string off the box and opened it.

Immediately, he was engulfed by a white fog as cold as the ocean. He cried out, knowing he would never see the Princess Otohime or the Dragon Palace ever again. The ghastly mist soared out to sea. Taro, on the shore, watched it fade into the tender blue sky, disappearing against the clouds.

Then, the burden of 400 years set upon his body all at once. His hair grayed, then fell out. His face drooped, his spine curled, his teeth dropped into the sand.

Asteroid Ryugu is nothing like its namesake.

Photos snapped by Hayabusa2 as it approached the rock showed a featureless gray diamond against the dark; a milky splotch on a black curtain. But when the spacecraft arrived on June 27, 2018, and moved within 12 miles of Ryugu's surface, its cameras captured every dip, bend and curve of its face. The team was shocked.

An image of Ryugu, taken by Hayabusa2's ONC-W1 camera on June 13, 2018, as the spacecraft began its approach.

It was no palace. It was a wasteland. Strewn with mammoth boulders and pockmarked by craters, Ryugu was immediately deemed "unfriendly" by members of the science team. "It was beyond our imagination," says Tsuda, project manager on the mission. "It's a really hopeless terrain."

Ryugu is what's known as a "rubble pile," a clotted mass of rock bound together by gravity. It likely formed when two large bodies collided in the earliest epoch of the solar system, some 4.5 billion years ago. The explosive impact would have showered space with debris. Over time, gravity pulled the wreckage together, forming Ryugu. It's been wandering in the orbit between Mars and Earth ever since.

Asteroids aren't considered sexy. They're dull, bumpy boulders traveling through an abyss. They're often maligned; we only really care for them when we think they might collide with the Earth. This is unfair. Asteroids are some of the most valuable resources in our solar system.

"Missions like Hayabusa and Hayabusa2, and Osiris-Rex, are a first step towards deflecting asteroids, and also mining them," says Jonti Horner, an astrophysicist at the University of Southern Queensland. Asteroid mining is too expensive to be feasible today, but demonstrating that samples can be gathered and returned from distant space rocks could lead to a greener, near-unlimited resource of Earth metals like copper, nickel and platinum. A similar process, Horner says, might help change the trajectory of an asteroid on a collision course with the Earth.

"One of the ways we could deflect it would be to send spacecraft there, land on the surface, and start digging bits off and firing those bits into space -- in a carefully calculated direction," he says.

Ryugu, the Dragon Palace, captured by Hayabusa2's ONC-W1 camera on June 30, 2018.

But asteroids aren't just destinations to visit, mine or move. They are also records of truly ancient history.

Rocks like Ryugu could hold clues to the evolution of the solar system and even the evolution of life on Earth. Observing Ryugu for over a decade, scientists learned it was a "C-type" asteroid rich in carbon, containing some of the oldest and most pristine material we know of, from a time when planets were only just beginning to form. They are believed to harbor water ice and organic compounds, making them "potentially important for supplying the basic ingredients for life on Earth and other planets," says Simon Turner, a geochemist at Macquarie University in Australia.

JAXA would be the first agency to visit a C-type asteroid and sample rock from its surface. But the team quickly realized just how problematic that surface would be.

If you want to tango with an asteroid, you have to have a really big dance floor.

"We needed a 100-meter-diameter flat area," says Tsuda, "but there's no such space on the surface of Ryugu." He was acutely aware of how things could go wrong, having worked on the first Hayabusa mission.

Hayabusa2 performed a touchdown rehearsal in September 2018, a month before the first landing operation was scheduled to occur. It approached Ryugu slowly, scanning the surface with a laser that gauges altitude. At a height of 600 meters, it stopped descending. The spacecraft had a memory lapse, losing track of the distance to the surface. To save itself, it autonomously backed away. After reviewing the issue, the team decided on postponing the first touchdown. They needed to find a good landing spot.

Scientists scoured images of Ryugu's surface, measuring the size of shadows cast by boulders and pebbles to estimate height. Tsuda thinks the science team counted 10,000 or more rocks to estimate the "bumpiness" of the terrain. After a week, the team located a safe area, dubbed L08-B, that was free from debris -- but it was one-fifth the size they required.

Tsuda reasoned that the team would have to rethink its strategy altogether. They would now perform a "pinpoint touchdown" method and, Takanao says, had to "study very, very hard" to pull it off.

JAXA members Hirotaka Sawada (left) and Satoru Nakazawa (right) in the Sagamihara control room during touchdown rehearsal on Sept. 11, 2018.

Originally, Hayabusa2 planned to drop a softball-sized, reflective marker to the surface during the touchdown operation and then follow it to the surface. But the team reasoned that if it dropped the marker a few months prior to touchdown, that would provide Hayabusa2 with a beacon it could use as a guide, like a lighthouse shepherding a ship to shore.

Fortunately, Hayabusa2 had already proved itself a master marksman. It had deployed two hopping rovers, Hibou and Owl, to Ryugu's surface, along with a third robotic scout, Mascot, developed by the German Aerospace Center and France's National Centre for Space Studies. The box-shaped hoppers were the first spacecraft to image an asteroid from the surface and measure properties never considered before. When it came time to land the target marker, the operation proceeded without fault.

Although the successes were mounting, the reason for visiting Ryugu was to sample it. "Without a successful touchdown, we could not go beyond Hayabusa," says Tsuda. Touchdown was all he could think about. He wasn't getting much sleep, he says. In late October 2018, the team dropped the target marker without issue. Two more touchdown rehearsals occurred in the new year, and the pinpoint method worked flawlessly. Finally, the team was ready.

With the sun rising over mission control in Sagamihara on Feb. 21, 2019, Tsuda donned his off-white Hayabusa2 mission jacket, and the team began its operation. The control room was calm. Expectant. But as they performed final checks on Hayabusa2 before descent, the mission was thrown into chaos.

Hayabusa2 was not where it was supposed to be.

The distance between Earth and Hayabusa2, floating above Ryugu, is about 210 million miles. Orders, uploaded from Japan, take about 20 minutes to reach the spacecraft. It's programmed to perform operations autonomously and, if something goes wrong, there's no opportunity to correct on the fly.

When JAXA found Hayabusa2 was not in position to start its descent, the touchdown plan had to be reworked once again. "We had to delay the start of the descent by five hours," says Tsuda. The slight delay might not seem significant, but in that time the team essentially reprogrammed Hayabusa2's guidance systems for the operation.

The "last hardship," as Tsuda calls it, changed the atmosphere in the room, but only slightly. The team quickly discovered a timing error had caused the mishap. They'd trained hard for these exact scenarios, running simulations hundreds of times on the ground. Tsuda's confidence and anxiety coalesced in the frenzied five-hour pause.

Finally, just after midday on Feb. 21, the touchdown operation was declared a "go." The new commands had been uploaded. The fate of Hayabusa2 rested solely in the spacecraft's hands. It descended.

Dozens of members crowded around a wall-size projection, in the control room, providing a readout of data streaming back from Hayabusa2. There was no live video, so the team followed the spacecraft's Doppler data: Against a gray table, drawn like a graph in Excel, they waited for a red line to appear -- a sign the spacecraft had survived its encounter with Ryugu and was moving away from the surface.

Takanao Saiki (front) and Yuichi Tsuda embrace.

The pressure was huge, Takanao, the engineer, says. As the team waited, Sakanao interlaced his fingers, as if in prayer, staring at the screen. Almost 25 hours after JAXA began the operation, the thin, red line blinked into existence on the screen. They'd done it. Hayabusa2 was not equipped with cameras inside the sample capsule, but data streaming back from the spacecraft showed it had fired its projectile and picked up a bucketful of material, storing it away for the return journey.

Applause broke out. Tsuda and Takanao high-fived. Team members embraced. The muted celebrations might have seemed strange to those used to watching broadcasts from NASA control rooms; energetic displays of relief and joy overwhelming team members. That wasn't the JAXA way. Tsuda recalled the feeling as one of "pure pleasure" and surprise. "We actually did that?" he asked himself, as other scientists wrapped him in fleeting hugs.

Hayabusa2 had done what Hayabusa could not. It had retrieved innumerable treasures from the ancient space rock. The team nicknamed the touchdown site tamatebako.

With its treasure box tucked safely away, the spacecraft could have waited the year out, analyzing Ryugu from orbit until it was time to return home. JAXA wanted to go one better.

One of Hayabusa2's major upgrades was the addition of a bomb.

Strapped to the underside of the spacecraft was an explosive known as the Small Carry-on Impactor that JAXA scientists, including Takanao, had designed for Hayabusa2 to drop on Ryugu to create an artificial crater and allow the team to sample material from beneath the asteroid's surface. But the team agonized over one key decision: Should they use it?

A second touchdown was a risky operation. Would JAXA take a chance on losing the ancient cargo it'd already captured to perform another risky touchdown and nab this pristine material? There was great uncertainty within the team.

Fujimoto says there were many "interesting" conversations leading up to the operation, describing heated debates about whether it was worth the risk. Tsuda notes that the first touchdown was "mandatory" for the mission's success, but the second touchdown was "the first time we purely pursued the scientific value."

It wasn't necessary to extract the first subsurface sample from an asteroid, but the team's scientists wanted to try. The material could unravel some of the secrets of C-type asteroids. For Fujimoto, not trying to collect the subsurface sample was akin to revealing the team wasn't confident in itself. He didn't want to risk "getting that reputation," he says. Eventually, a consensus was reached: They would go for it.

On April 5, 2019, a five-pound copper disc was volleyed from the SCI at a speed of 2 kilometers per second. It collided with Ryugu's side and sprayed rock across its body, leaving a scar on the surface about 32 feet wide and six feet deep. "This exposed subsurface material around the artificial crater," Tsuda says.

The SCI departing Hayabusa2 en route to bombing Ryugu.

Scientists could pick practically anywhere safe on the surface for Hayabusa2's first landing. But for the second, there were no options. "To collect subsurface materials, we must land near the artificial crater," says Shota Kikuchi, a JAXA engineer who helped plot the second landing. But the team did get "really lucky," according to Yuri Shimaki, a post-doctoral engineer at ISAS, because the SCI hit at such an angle that Hayabusa2 could retrieve an abundance of ejected material. Not before a lot more training, though.

The engineering and science teams simulated touchdown operations from the mission control room on Earth, running through hundreds of scenarios. One team member would be assigned the role of "God," tasked with simulating the entire second touchdown from start to finish.

During one simulation, "God" was in on a conspiracy to derail the simulation. The member had tasked one of the engineers to complain of stomach problems, right as the spacecraft in the sim began its descent to the surface. The engineer played along, crying out in pain, rushing to the toilet and disappearing. But the simulated mission carried on in that engineer's absence.

"Make the most of your chances!" The Ryugu-no-tsukai in JAXA mission control.

Tsuda says the team pulled together and, ultimately, the simulation was a success.

On July 10, 2019, the second touchdown operation began. It was a carbon copy of the first, but this time a plush Japanese oarfish (a "Ryugu-no-tsukai") hung in the room with a message: "Make the most of your chances! That is the principle of space research!"

Team members huddled around the Doppler data on the wall for a second time. At 10:51 a.m. on July 11, Tsuda declared the mission a success. The celebrations, too, were a carbon copy, but this one meant a little more. JAXA had taken the risk and succeeded. Looking back, Fujimoto calls the second touchdown "one of the defining moments" of his career.

With two bags of ancient rock now stowed safely within its sample capsule, it was time for JAXA to bring Hayabusa2 home.

See the article here:

Inside Japan's daring 10-year mission to visit ancient asteroid Ryugu - CNET