In the dusty red heart of the South Australian outback, a small town with an explosive past is waiting for a delivery from space.
Established in secret in 1947, Woomera was at the centre of the Australian and British space race projects for more than three decades. Its flat, expansive landscape just 500 kilometres north of the city of Adelaide was perfect for rocket and missile testing – but this time, a payload isn’t going up: it’s coming down.
In the small hours of Sunday morning, the landing capsule from the asteroid-sampling mission Hayabusa2 will touch down in the Woomera Prohibited Area.
This capsule has travelled 5.2 billion kilometres over the past six years, and just last year took two samples from the primordial asteroid Ryugu, a 4.5-billion-year-old lump of rock left over from the chaos of the formation of the solar system.
This will be only the second time an asteroid sample has been returned to Earth – and the first-ever sample from beneath an asteroid’s surface.
Needless to say, scientists are excited: 79 Japanese mission specialists are currently on the ground in Woomera, having overcome COVID-19 setbacks to reach Australia to recover their precious cargo.
Glad to be out of their two weeks of quarantine in Adelaide, the Japanese Aerospace Exploration Agency (JAXA) team is busy training for the big moment, when they’ll use a helicopter to scan the rust-red expanse of desert and find where the capsule – just 40 centimetres in diameter – has parachuted down to Earth.
“Around 4am in the morning of the sixth of December, there will be a fireball running across the sky above Cooper Pedy, 400 kilometres north of Woomera,” says Masaki Fujimoto from JAXA. “That’s going to be a spectacular view so if you happen to live close to it, you better wake up early and watch the sky.”
The fireball will be brightest when it’s approximately 40-50 kilometres above the Earth’s surface. Fujimoto explains that this might seem “like the grand finale – “Oh the capsule has come back to Earth!” – but for us, it’s really the bell that’s ringing and telling us this is not a drill.”
As it heads towards Woomera and its altitude drops, the capsule will deploy a parachute and a beacon will be activated.
“We will triangulate the signal to reconstruct the trajectory of the capsule, then we’ll get a good guess of where the landing spot of the capsule will be,” Fujimoto says.
By then, JAXA mission specialists will be on the move, launching from the Woomera heliport to head out across the predicted landing area.
But they won’t have a precise location. Right now, JAXA has calculated a conservative landing area spanning 100 by 200 kilometres, but once weather predictions – in particular, wind predictions – become more accurate, the landing area will narrow to within tens of kilometres.
The helicopter will need to rapidly trace the capsule’s signal over this predicted area, zeroing in on the landing spot. Sample scientists will be among the recovery team, trusting no one else to take care of their rare and long-awaited cargo.
This is an urgent process. Fujimoto explains that within 100 hours, the sample needs to be recovered and returned to Japan to be stored in a specialised facility – otherwise it risks becoming degraded.
But although the capsule won’t be opened until it’s in Japan, the team will be able to take a quick look at it in Woomera to determine whether or not they have actually recovered a sample. Fujimoto says that judging from video clips the spacecraft took during its landing on Ryugu, they appear to have obtained a one-gram sample.
“One gram may sound small for some of you, but for experts, one gram is huge – it’s enough to address the science questions.”
The fact that this sample will be sealed – and therefore uncontaminated by Earth’s organic material – is an even bigger deal, as it will allow for a more accurate study of asteroids and of the early solar system in general.
This isn’t the first time that the JAXA scientists have been waiting in Woomera, eyes turned to the sky to await a piece of outer space. In 2010, the Hayabusa1 mission returned the first-ever asteroid rock samples to Earth. When the capsule was opened back in Japan, scientists found just 1500 tiny dust grains – less than a milligram in total, but perhaps the most hard-won geological sample in history.
Ryugu is very different to the stony asteroid Hayabusa1 visited: Ryugu is carbonaceous, meaning it is rich in water and carbon. Scientists are frothing at the mouths to get their hands on unspoiled samples of this chunk of rock, hoping it will teach them more about the formation of the solar system – and perhaps even help them understand whether these types of asteroids first brought water and the building blocks of life to Earth.
But JAXA mission specialists aren’t the only ones currently up in the desert.
near Woomera, seven years and two billion kilometres
after its journey began. Credit: JAXA
Australian scientists are on the ground as well, and they can’t wait for Sunday morning, according to Ellie Sansom of the Desert Fireball Network (DFN). She’s in the middle of preparations to observe the “fireball” the landing capsule creates during its blistering re-entry into the atmosphere.
“Fireballs are so rare that it’s a once-in-a-lifetime event to see one in any case,” she says. “The bright fireballs we look at normally last about four to six seconds, whereas this one should be about 30 to 40 seconds. It’s going to be really amazing to see.”
The Desert Fireball Network, based at Curtin University in Western Australia, has an existing network of cameras set up across the country to capture images of meteors as they burn up in the atmosphere. They use the information to not only triangulate where the meteorite landed, but also to trace back its previous orbit and figure out where it came from – and thus learn more about our solar system.
The Hayabusa2 event provides a unique opportunity for their research. Usually, they have no idea when or where meteors might appear – but on Sunday, the team will have all the information.
“This is a fantastic test for our software, figuring out how well we can actually predict the position of that capsule as it comes through our atmosphere, as well as where it lands,” Sansom says. “And, most importantly, how well we can match the orbit that it came from.”
Sansom and colleagues have based themselves in Cooper Pedy, which will have the best view of the capsule as it soars through the sky at 12 kilometres per second, bound for Woomera. Her team is currently busy setting up over 50 instruments at sites all along the Stuart Highway – not just cameras, but also seismometers and infrasound microphones to capture the sonic boom it creates as it travels through the sky.
These extra instruments were recently shipped to Sansom’s team by their collaborators in Japan.
“Unfortunately, our colleagues from Japan were unable to come in person because of COVID-19, and we’ve been given the huge responsibility of carrying on their projects,” Sansom explains. “When COVID happened when we went to Plan B, and now we’re working on Plan E or F – I’m not quite sure which one we’re on now!”
After going through their own pandemic-related setbacks – almost unable to make it across the WA-SA border due to a recent outbreak in SA – the team have spent the last week scouting out where to place the instruments and securing final permissions. They recently met with a JAXA infrasound specialist down in Woomera to discuss the infrasound microphones, and they’ve been talking with station owners – many of whom are currently busy mustering – about where to place their instruments without getting in the way.
They’re also monitoring the weather forecast pretty closely – cloudy skies are on the horizon, though the team is crossing their fingers for no wind.
Either way, come Sunday morning, four of the instrument sites along the Stuart Highway will be manned as Sansom and her team await the capsule’s re-entry. “I don’t think there will be any sleep involved – the adrenaline is too high,” Sansom says with a laugh.
She and her team will need to quarantine on their return to Western Australia, just like the two weeks of quarantine facing the JAXA team when they head back to Japan later in the month. But it undoubtedly will be worth it for the out-of-this-world rock collection they’ll be taking home.
And while the landing capsule’s journey will soon be over, Hayabusa2 – the half-tonne spacecraft itself – is far from finished. On Sunday morning, not all eyes will be on the capsule; the Deep Space Network (DSN) in Canberra will instead be keeping tabs on Hayabusa2 as it skips back out from the Earth’s atmosphere and returns to space for another decade of work.
“After the Hayabusa2 mothercraft releases the sample capsule, it will divert its course and travel to three other asteroids, encountering them between 2026 and 2031,” says Ed Kruzins, director of the Australian node of the DSN: CSIRO’s Canberra Deep Space Communication Complex.“One of those will be called 1998 Ky 26, which will be approximately 10 billion kilometres away from Earth.”
Along with tracking 35 other international space missions, the DSN – which also has nodes in California and Spain – will keep tabs on the Hayabusa2 mission into the future.
The journey from outer space to the outback might be over, but the mission to understand the Solar System has only just begun.
Lauren Fuge
Lauren Fuge is a science journalist at The Royal Institution of Australia.
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