New Mexico’s Plains of San Agustin are otherworldly: Silence, sand and sharp plants reign on the valley floor. Knobbly volcanic rock rises above. Pronghorns’ legs and jackrabbits’ ears break up the landscape.
And so, too, does one of the world’s largest telescopes.
The plains house the aptly named Very Large Array (VLA)—a radio telescope made of 27 different antennas, each of which looks like a home satellite dish on steroids. In the otherwise empty desert, they spread into a Y shape that can extend 22 miles end-to-end. When the antennas are pointed at the same thing in the sky at the same time, they function together as one large telescope, simulating an instrument as wide as the distance between the dishes. In this case, then, images from the VLA have as much resolution as they would if it were a single telescope 22 miles wide: high definition, in other words. The VLA became iconic, and inspirational to a generation of astronomers, thanks to the movie Contact, in which Jodie Foster’s character uses the array to hear an alien communication.
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The VLA’s antennas, the true stars of the film, simultaneously look like they don’t belong in the landscape and also like they’ve always been here. They haven’t, of course, but their construction began in the 1970s, making the VLA the oldest instrument in the portfolio of the National Radio Astronomy Observatory (NRAO). This federally-funded organization builds, maintains and operates radio telescopes that any astronomer—regardless of their institutional affiliation or citizenship—can apply to use.
But the VLA, now in its middle age, is due for a replacement. After all these decades, astronomers want something shiny, fully modern and more capable: a new build with all the bells and whistles rather than a charming old Colonial that’s been remodeled piecemeal. NRAO is working on that, planning the VLA’s proposed successor: the Next-Generation Very Large Array (ngVLA). (Astronomers may be scientifically creative, but they are linguistic straight shooters.)
A close-up view of a prototype antenna for the proposed Next Generation Very Large Array radio telescope.
National Science Foundation/National Radio Astronomy Observatory
On a Friday afternoon in late April, the organization gathered political leaders together, alongside scientists and engineers, to unveil a prototype antenna—one that will be cloned a couple of hundred times to make up the future ngVLA. It loomed on the plains just beyond the partygoers, standing alongside its predecessors, the old and the new in stereo with each other. “The amount that technology has advanced since the VLA was created is amazing,” says Jill Malusky, NRAO’s news and public information manager. “A VLA antenna and an ngVLA antenna look very different because they are.”
Guests wandered near the antennas, checking out a spread of food that included a sculpture, made in the medium of watermelon, of a radio telescope antenna. A chamber quartet played in the background, a single fern fronting them, with an open bar lubricating the event. It was fancy—for science. But for astronomers, the ngVLA is a big deal, and the event was intended, in part, to bolster the political support needed to make it happen. At the moment, it’s a proposed project—and still requires final funding. “Having a physical antenna we can point to, and test, to prove the value of this project is such a milestone,” Malusky says. “It makes it all more real.”
Representing an orders-of-magnitude improvement to the VLA that would complement other radio telescopes in the U.S. and abroad, the ambitious project has the enthusiastic yes of the astronomical community. But whether big-science telescopes, radio or otherwise, will survive the current funding environment remains a dark matter. That uncertainty is part of why NRAO’s event elicited a spectrum of emotions for Malusky. “It’s a mix of excitement and trepidation,” she says. “Can we get people invested in the potential of a major project that is still gathering resources and just over a decade to fruition?”
A Vanguard Antenna
That Friday afternoon, Tony Beasley, director of NRAO, stood at the front of a hardy event tent and faced the prototype. Its dish was made up of shiny panels assembled into an octagon. From its bottom edge, supportive struts held up a secondary reflecting surface and a receiver (basically the radio version of an optical telescope’s camera) that looked a bit like the spaceship Foster’s character boarded in Contact.
The antenna, about as wide as a bowling lane is long, has been designed to collect radio waves from space—beamed from stars that are being born or dying, the stuff between stars, and more. As radio light comes in, it will hit the main dish and bounce up to the secondary reflector and then the receiver, which will catch the waves and turn them into digital signals that will then be sent to computers.
As a start, the prototype dish will hook up to VLA’s aging ones and gather data alongside them—it will be an apprentice of sorts.
“You see one antenna out there,” said Beasley, directing the audience’s attention beyond the tent, which was being shaken by the wind to such an extent that people also cast their eyes upward to assess its structural integrity. NRAO ultimately plans to build 262 more antennas and spread them across the U.S., with their numbers concentrated in the Southwest. Of those antennas, Beasley continued, “192 of them will be visible from where I’m standing right here.”
Together, the ngVLA’s antennas could pick up a cell-phone signal from 500 billion kilometers (more than 310 billion miles) away (although that wouldn’t be the most likely find). That means it could detect an Android embedded in the Oort Cloud, the collection of comets that makes up the outer part of the solar system. The future telescope’s resolution should be high enough to pass a no-glasses eye exam in New York City if the chart of letters were placed in Los Angeles.
That precision gives it scientific latitude, allowing it to address some of astronomers’ highest-priority questions, such as how planets come to be and how solar systems like ours form. “You could, say, probe a cloud that is forming planets and find out where the planets are—like individual gaps in the cloud that the planets are carving out,” says David Kaplan, an astronomer and physics professor at the University of Wisconsin–Milwaukee.
Of all the radio telescopes out there, the ngVLA would be the planetary “flagship” for star and planet formation, Kaplan says. At high radio frequencies and big antenna separations, “it would be the only game in town.”
The ngVLA will also look for the organic molecules and chemical conditions of new solar systems that might someday spur life. It will show how galaxies come together and evolve, use the Milky Way’s center to test ideas about how gravity works and investigate how stars develop. And it will hunt black holes and their outbursts.
Given those varied abilities, the telescope was highly ranked in astronomers’ “decadal survey,” a yearslong process in which the astronomical community takes stock of its most valued scientific questions and assesses which future telescopes are best suited to find some answers. Funding from agencies such as the National Science Foundation (NSF), which bankrolls NRAO, typically follows the survey’s recommendations.
The survey recommended the ngVLA as a top priority. “It can change the landscape,” says Matt Dobbs, a physicist at McGill University, who studies the origin and evolution of the universe and worked on the survey alongside Kaplan.
Telescope Prospects
NRAO hopes to start construction on the ngVLA in 2029, with initial operations beginning in 2033. The possibility is a bright spot for American radio astronomy. The VLA is more than 40 years old; the Green Bank Telescope, completed in 2001, is more than 20. And NRAO’s latest instrument, the Atacama Large Millimeter/submillimeter Array, opened 12 years ago.
The latter two, though not new, aren’t going anywhere, as far as anyone knows. But they do different kinds of scientific analyses than the VLA does and the ngVLA will.
The new telescope does, though, have a whippersnapper nipping at its heels. Another future radio observatory, called the Deep Synoptic Array 2000 (DSA-2000), is planning an order of magnitude more dishes than the ngVLA—2,000 of them. But each will be only around 16 feet across, whereas ngVLA’s dishes will measure 60 feet. DSA-2000 will also work at a different radio frequency range than the ngVLA.
DSA-2000’s development is also moving faster than that of the VLA’s successor, though, in large part, that is because the former has relied on private funding more than federal resources, as the ngVLA’s prototyping has.
In taking a step back from dependence on the NSF, the DSA-2000 crew might be on to something. Just days before the ngVLA ceremony, the NSF canceled more than 400 active grants; one day before, the agency’s then director Sethuraman Panchanathan resigned. “This is a pivotal moment for our nation in terms of global competitiveness,” he said in his goodbye letter. “NSF is an extremely important investment to make U.S. scientific dominance a reality. We must not lose our competitive edge.”
No one knows what the future of NSF-funded astronomy, let alone NSF-funded radio astronomy, looks like. President Donald Trump hasn’t said much about that particular domain yet. But not building the ngVLA could put that edge in jeopardy.
Dobbs, though, holds out hope for the U.S.’s role in radio astronomy’s future, in part because of the propulsion of its past.
“The United States has everything it needs to make that project a reality,” he adds. Whether it will do so, though, requires gathering more data from the future. After all, it’s bad luck to count your antennas before they hatch.
Dobbs has been putting his focus on smaller radio telescopes, such as one called the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and its successor, acronymed CHORD. Both map how hydrogen was distributed in the early universe and detect fast radio bursts. Their antennas are cheap(ish), their overall footprint small, and their ambition is limited to specific science—in this case, gas maps.
At the prototype-antenna unveiling, then, it made sense that there was a liminal feeling to what was otherwise a celebratory gathering. And it was conspicuous that representatives from NSF, the agency that would fund the telescope’s construction and operation, weren’t there, which Beasley said was the case “for various reasons.”
Chris Smith, interim director of the NSF’s division of astronomical sciences, did send a letter to be read to the wined-and-dined crowd. “NSF funded this development not just to ensure the technical feasibility of the advanced capabilities of ngVLA,” he wrote. It also supported the prototype as “a way of creating new innovations in the field of radio astronomy.”
And that may be true. But those who gathered at NRAO’s event also hope, specifically, that the ngVLA, a receptacle for optimism about the future of radio astronomy in the U.S., will sprout from this dry ground.
“It starts with a single step,” Beasley said at the event—in this case, a single antenna.
