A telescope the size of a stadium is rising in the Chilean desert. It promises images of the cosmos sharper and richer than we've ever seen. The only problem? It's never been done before.
Davide Deiana could be a building site manager anywhere. He wears the fluoro vest and unflappable demeanour of a bloke who knows what he's doing.
"We are pushing the current engineering limit," he says matter-of-factly.
"Everything has to work perfectly."
Mr Deiana's assignment looms atop the mountain behind him, flanked by cranes leaning up into the wide blue skies of the Atacama Desert.
The task is simultaneously gargantuan and fiddly: a thumping great building which is also a delicate scientific instrument.
The Extremely Large Telescope or ELT will be the most powerful optical telescope ever built.
When it opens for business in 2028, it promises to reshape our view of the cosmos.
Astronomers from more than a dozen countries will start bidding for the chance to use it — and Australians could be among them.
But that invitation currently hangs in the balance.
There's remote work, and then there's this
Big telescopes are often tucked away in remote locations — mountains, islands, deserts — because astronomy needs quiet spaces.
But this landscape is desolate.
In the two-hour drive from the mining port of Antofagasta, there's not a tree in sight.
The only rare signs of life are industrial — a train carrying ore, or a distant solar farm — and it's all dwarfed by undulating dunes and ridges in never-ending shades of brown.
At the crest of one of those ridges 2,500 metres above sea level is the Paranal Observatory: a suite of existing telescopes run by the European Southern Observatory (ESO) and a hotel custom-built for stargazers.
The red-brown brutalist building, which doubled as the villain's lair in the 2008 film Quantum of Solace, is an oasis housing up to 150 staff.
"We try to make this place feel like a home away from home," head of logistics and facilities Vanessa Peidro says.
"Because our staff members and contractors … spend more or less half their life here."
Like many staff, Ms Peidro alternates weeks living here with a home in Santiago: "In the end, it's like a family. After many years people really know each other."
Maintaining a facility like this in the desert is not cheap, nor easy. A pool in the entrance hall helps to soften the parched Atacama air; there's a well-stocked kitchen and a nine-megawatt solar farm nearby.
Water arrives by truck: 12 tankers every week.
"It's a lot," Ms Peidro says. "So we are making a lot of effort to become much more sustainable. This is one of our main goals."
There are also requirements that are peculiar to an astronomy hotel.
"You will see shutters and curtains everywhere. It's very important that we do not have any light pollution."
A trailblazing predecessor
On the crest of the hill beside the residence stands the Very Large Telescope or VLT: the existing top-of-the-range "eye on the sky" run by the ESO.
"We might not be very creative with naming our telescopes, but the names are very descriptive!" media officer and astronomer Juan Carlos Muñoz says.
"It may sound cheesy, but even as a kid I used to read about the first light of the VLT … I didn't imagine that I would end up working here."
The VLT, which is actually a set of four 8m telescopes, recorded its "first light" in 1998.
It has a long list of scientific achievements, including the first ever image of a planet outside our Solar System and Nobel-winning measurements of how fast the universe is expanding.
These discoveries happen in the depths of night, thanks to astronomers and telescope operators who work the graveyard shift.
Straight after sunset, the VLT control room fills up with staff and visitors who will spend the rest of the night directing the telescopes and monitoring data collection.
"I like to think of us as a Formula One pilots," says Eleonora Sani, deputy head of science operations at Paranal.
"The systems here are all prototypes — each instrument is unique. So to keep it performing and to execute observations, you need someone very specialised in it."
Other staff here work more usual hours, keeping the place running, doing engineering work and making plans — including for the ELT, which is taking shape 20 kilometres to the east.
"The ELT is going to be a revolution," Dr Sani says.
"Each single observation with the ELT is going to be mind blowing — something that has never been seen with such depth, with such granularity … It's going to allow us not just a step forward, but a jump."
Location is everything
Besides technology, the key to the success of the VLT — and the promise of the ELT — is their real estate.
It's very high and unbelievably dry, which helps the telescopes record crisp images.
It's also very, very dark.
Going outside on a moonless night is like suddenly putting on a blindfold that you can't feel.
At first, there's nothing.
This kind of darkness challenges the senses; it feels almost as profound as seeing the stars.
They come next — slowly — as your eyes turn up the volume on the sky.
Soon they are deafening.
And on some nights, you might see the VLT shining lasers into sky.
At 22 watts each — roughly 4,000 times more powerful than a standard laser pointer — these four dead-straight beams are clearly visible to the naked eye.
Each laser creates an artificial "guide star" when it hits sodium atoms 90km above the ground.
A computer tracks how much these fake stars twinkle, which happens because of turbulence in the air. It then reshapes one of the telescope's mirrors, using small electronic pistons pumping up to 1,000 times each second, to cancel out the distortion in real time.
It's as if the VLT, already under a privileged sky because of its altitude and climate, were actually in space.
The ELT will have this system too — and, like almost every aspect of its construction, for a telescope five times larger the engineering challenge is at least five times greater.
When daylight returns, if you stand next to the VLT and look to the east, you can actually see the bones of its successor rearing up from the desert.
But you need to get much closer to understand its scale.
The future is even larger
At the end of a winding 30-minute drive further into the desert, there's a cluster of demountable sheds.
This "base camp" is tucked into the shoulder of Cerro Armazones: the mountain whose peak was levelled with dynamite to make way for the ELT's foundations.
It's where Davide Deiana works as the deputy site manager of the ELT's main structure. He seems perfectly at home here, doling out dizzying numbers as if picking them from orderly shelves somewhere inside his head.
The dome reaches 22 storeys high and 87m in diameter …
This 6,000-tonne building will rotate up to a full turn-and-a-half … The telescope inside will spin independently with microscopic precision, sliding on a hair's width of oil …
The 39m main mirror will be a curved honeycomb of 798 hexagonal panels, each with three pistons and 12 edge sensors to maintain its perfect parabolic shape …
Both telescope and dome rest on dozens of custom-designed seismic devices to cushion the $2.4 billion machine from Chile's famous earthquakes.
"I've been asked once, 'What do you find most fascinating about this project?'" Mr Deiana recalls. "My answer is, 'Which branch of engineering do you like more?'
"You have the civil engineering point of view, the mechanical installation, control systems, environmental controls, optics, chemistry for the selection of the material for the mirrors, the physics behind the instrumentation.
"Everything has to work together like a symphony."
From Mr Deiana's office, it's a slow and careful 15-minute drive to the top.
Stepping out of the minibus into a swirling, bone-dry wind, he says with a proud half smile, "Welcome to the Colosseum of Chile".
A skeletal steel dome squats on an immense, circular concrete base.
It dwarfs the dozens of scurrying workers on the ground, doing what they can on a blustery day. At 74m, it's actually taller than the Colosseum in Rome.
Standing in its shadow, it's impossible to take in the ELT with a single glance. I find myself turning in circles, alternating between the construction and the view over the Atacama.
It's difficult to imagine this dusty, noisy building site as a finely tuned astronomical instrument.
But back across the desert, inside a hangar near the Paranal Residence, work is underway on the glittering jewel that will sit beneath the dome: a mirror the size of four tennis courts.
The hall of mirrors
Making telescope mirrors is a finicky business. Everyone who steps inside the cleanroom at the ELT Technical Facility must be shrouded head to toe like a surgeon; stray particles are a hazard to science.
This lofty space is where the gleaming hexagonal segments are tested, fitted with electronics and coated in silver.
Each arrives from Germany in its own refrigerated container.
"All the electronics and the mechanics are quite sensitive to changes in temperature," optic coatings engineer Ricardo Parra explains.
There will be six matching "petals" of 133 hexagons in the main mirror — 798 in total, plus another 133 spares. Once the ELT is operational, a petal's-worth of segments will always be here in the technical facility being cleaned and refreshed, ready to be rotated into service on the mountain.
As a final kicker to these mind-boggling logistics, each of the 133 segments in a "petal" is slightly different. If they get muddled, "the telescope will not work", engineer Tobias Müller says.
"And our expectation is, once we start with the first segment, everything will be perfect. We will not fail."
The science
At present, humanity's sharpest-ever views in visible and infrared light come from the James Webb Space Telescope. Its 6.5m mirror stares into space from a vantage point 1.5 million km from Earth, regularly snapping images of the faintest, farthest stars and galaxies on record.
Sitting firmly on the rocky Atacama, the ELT aims to leap beyond that — both in the brightness and sharpness of its view.
With its 39m main mirror, it will catch 15 times more starlight than the biggest telescopes on Earth to date and 40 times more than the James Webb Telescope.
Plus, with its ideal location and laser beams working to subtract the atmosphere's twinkle, the ELT promises to pick out individual stars in faraway galaxies and transform the search for alien worlds.
"For the first time, we should be able to directly detect Earth-like planets, in Earth-like orbits, around stars like our Sun, over a big volume of the nearby galaxy," says Matthew Colless, an astronomer at the Australian National University who served on the ESO governing council.
"So hopefully we'll come up with a list of other Earth-like planets that we can try talking to and see if there's anybody home."
Who gets the view?
The ELT is not the only planned "mega-observatory" of its kind. But right now, it's the only one with a clear path to completion.
Two US-led schemes stalled and are seeking more funding from Congress. One of them, the Giant Magellan Telescope, has at least laid its foundations, a day's drive south across the Atacama from the ELT.
Meanwhile the "Thirty Meter Telescope" slated for Hawaii faced fierce protests from Indigenous Hawaiians and may have to relocate.
The ESO, by contrast, gets large annual contributions from its 16 member states. Despite tense periods in its 60-year history, the consortium has a mostly positive relationship with Chilean authorities and the local community.
As host nation, Chile is allocated 10 per cent of the operating hours of all ESO telescopes, while astronomers from European member countries compete for the rest.
Australian researchers have also been using ESO facilities, including the VLT, since 2017 under a "strategic partnership".
But this entry-level membership expires in 2027.
"At the end of that 10-year trial period, Australia has to decide whether it wants to join as a full member state or withdraw entirely," explains Professor Colless.
"It's an up-or-out situation."
The price tag for full membership is about $400 million, spread over 10 years to 2037.
Professor Colless says this would mean about a 50 per cent increase in what Australia currently spends on astronomy — and probably no longer supporting the Anglo-Australian Telescope at Siding Spring, a 4m telescope with a proud 50-year history.
Nonetheless, Professor Colless believes that $40 million per year for access to everything the ESO offers is a no-brainer.
"I think that you'll find that most Australian astronomers would say joining ESO is make-or-break for our field in this country."
A spokesperson for Industry and Science Minister Ed Husic said full ESO membership was "yet to be considered".
If it's going to happen, the government will need to start allocating funds in the 2025 federal budget.
The next generation
Inside the busy control room of the VLT, Nicholas Borsato is visiting for one precious night of observing.
He's a PhD student from Macquarie University and Lund University, still at the beginning of his astronomy career.
"I'm looking at the transit of a sub-Neptune," Mr Borsato explains.
"It's a planet that's smaller than Neptune but larger than Earth and it's very, very close to its star."
He first saw pictures of ESO telescopes as a first-year undergrad. Ten years later, he got a VLT observing proposal accepted thanks to Australia's strategic partnership.
It has lived up to the dream.
"It's like Disneyland for astronomers. You have everything you could want here."
By the time the ELT comes online, Mr Borsato will have finished his PhD and hopes to be a working astronomer. He would love to bid for a chance to point its gigantic mirror at a target of his choosing.
If he's to get that chance, it will depend on Australia joining the ESO — or his choice of country for his next career move. He hopes it's not the latter.
"I think if Australia wasn't part of [ESO], we would start to be left behind, or most of our optical scientists would probably have to look for jobs overseas."
Now past the official midpoint in its construction, the ELT is gradually looking more like a telescope.
Cladding is starting to cover its skeleton. A support structure for the main mirror is in place.
But there are innumerable challenges still ahead.
"It is a tough environment, this is for sure," deputy site manager Davide Deiana says.
"But … you are building something that is a once-in-a-lifetime project.
"If you are working here, it's because you love what you do."
Credits:
- Reporting and digital production: Jonathan Webb
- Editing:
- Drone videos: G Hüdepohl / ESO; Jakub Kyncl; Ace / Cimolai
- Night sky VLT stills: M Zamani / ESO; Jakub Kyncl
Jonathan Webb's travel and accommodation costs to visit the ELT were covered by the European Southern Observatory. The ABC’s policies on independence and acceptance of free travel can be found in our Editorial Policies.
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