American astronomers are calling for the development of a whole new suite of grandiose space telescopes that will be able to peer into the atmospheres of planets beyond our Solar System, listen to black holes ringing as they form throughout the Universe, and look back in time to when galaxies first emerged. It’s all part of an ambitious long-term strategy to create the next generation of tools to study the most distant reaches of space, with the hopes of launching these spacecraft throughout the 2030s and the 2040s.
Astronomers laid out their vision for this future in a report known as the Decadal Survey on Astronomy and Astrophysics, released today by the National Academies of Sciences. Compiled every 10 years after extensive meetings and debate, the survey is essentially a wishlist, detailing the highest priority missions astronomers would like NASA to build in the coming decade. Decadal surveys of the past have led to the formation of some of NASA’s most enterprising missions, such as the Hubble Space Telescope currently in orbit around the Earth, and the James Webb Space Telescope, or JWST, which is set to launch into deep space before the end of the year.
Typically in their report, astronomers will provide a list of missions they’d most like to see move forward, ranked in order of priority. This year, the recommendations are a little different. Similar to past surveys, the new survey recommends building one big “flagship” space telescope—a behemoth that can see infrared, optical, and ultraviolet light in the atmospheres of planets that are 10 billion times fainter than the stars they orbit, searching for signs of life. But the report also recommends developing two smaller telescopes—one that sees X-rays and one that sees in far-infrared—almost simultaneously while investing in various ground-based telescopes and space missions already in development. They’re calling this pipeline the “Great Observatories Mission and Technology Maturation Program,” and it would result in multiple spacecraft being built together.
That way, in several decades’ time, astronomers will have an entire fleet of new space telescopes providing the most comprehensive picture ever of the distance Universe. Many in the science community are thrilled about that idea. “The Decadal team rose to the challenge,” Heidi Hammel, the vice president for science at Association of Universities for Research in Astronomy, a consortium of academic institutions that operate major telescopes, tells The Verge in an email. “They laid out the awesome science, and they made bold choices, both for ground-based and space-based facilities. I am so happy right now.”
The Search for Another Earth
The biggest goal laid out in the Decadal Survey — and the priority of its flagship space telescope — is finding and cataloging worlds beyond our Solar System. The first of these distant planets, known as exoplanets, were only discovered in the early 1990s. Since then, astronomers have cataloged thousands more, completely transforming our understanding of the cosmos. Now that we know exoplanets are common, scientists are on the hunt for one — or more — that might be home to alien life.
The problem is that studying exoplanets is unbelievably difficult. These worlds are extremely far away, typically orbiting very bright stars that overwhelm them in light and wash them out. That prevents astronomers from seeing exoplanets directly. Instead, scientists must infer their presence, either by staring at a distant star and waiting for it to dim ever so slightly — a sign that a tiny world is passing in front of it, blocking its light — or measuring how distant stars wobble due to the gravitational pull of a nearby planet.
But just knowing an exoplanet exists is not enough to answer the ultimate question: are we alone? Astronomers are desperate to peer into the atmospheres of these distant worlds to see if they might resemble our own. The pinnacle of exoplanet discovery would be to find an exoplanet with just the right gases in its atmosphere, parked in a Sun-like star’s habitable zone — a spot where it’s not too hot and not too cold, allowing water to pool on the planet’s surface. But we’ll never find that if we’re stuck watching stars as they dim and shake.
With a giant space telescope that sports a 20-foot (6-meter) dish that can see in bright types of light, astronomers believe they’ll be able to finally see an abundance of exoplanets directly, including the ones that are just too faint to look at now. That way, we might be able to find Earth’s twin and perhaps even confirm the existence of life on it. “We focus our specifics around the scientific achievements that we want to see happen,” Keivan Stassun, a professor of physics and astronomy at Vanderbilt and one of the committee members who wrote the new Decadal Survey, tells The Verge. “We want to discover Earths. We want to discover habitable worlds. That is a specific scientific priority.”
To design this new giant telescope, engineers will likely draw from two proposed observatory ideas that have already been sketched out in detail. Before completing the decadal survey, four teams of scientists came up with four different proposals for space telescopes, providing a framework for what future flagship missions could look like. Two of the four teams, LUVOIR and HabEx, proposed telescopes that could search for habitable worlds. HabEx called for a bold plan to build a starshade, which would fly in front of the telescope and block out light from distant stars, making their exoplanets easier to see. LUVOIR called for a monster space telescope that looked a bit like NASA’s upcoming JWST spacecraft, upgraded to the extreme. HabEx’s proposed budget hovered between $8 and $10.5 billion, according to the new survey, while LUVOIR’s was a whopping $17 billion.
The decadal survey doesn’t recommend building either HabEx or LUVOIR specifically. The report notes that HABEx wasn’t quite ambitious enough in scope and that LUVOIR was a bit over the top in terms of budget. Instead, the report simply lays out what the astronomy community wants these telescopes to do, which should help inform their final design. The researchers who worked on these projects are pretty happy about the decision.
“It’s absolutely amazing,” Scott Gaudi, a professor of astronomy at Ohio State University and co-community chair for the HabEx study, tells The Verge. “It is the best possible outcome I could have hoped for, not just for me, but also for all the people that worked on these large mission concepts.”
More than One Great Observatory
Searching for habitable worlds isn’t the astronomy community’s only goal for the next 10 years. It also wants to learn more about the densest objects in our Universe, like black holes and neutron stars, and the cataclysmic events that give rise to them. Astronomers also want to be able to peer inside distant galaxies right as they’re forming to learn more about how they evolve and birth millions of new stars.
It’s a lot to accomplish, which is why the decadal survey calls for more than just one new spacecraft. The authors say that the addition of an X-ray telescope and a far-infrared telescope will be the best way to achieve all of these tasks. In order to get everything they want, the report’s authors propose that mission planners get started on development of the big exoplanet-hunting telescope right away, sketching out the exact technologies they’ll need to start building the spacecraft. If that process goes well over the next five years, then it’ll be time to begin designing the X-ray telescope and the far-infrared telescope. All of these vehicles can then be developed and built around the same time. The two smaller telescopes would cost between $3 and $5 billion and launch in the 2030s, while the larger telescope would cost roughly $11 billion and launch in the mid-2040s.
It feels like a bold plan, especially since space telescopes typically go over budget. NASA’s next big space telescope, the JWST, was originally supposed to launch as early as 2007 and cost less than $1 billion. Now, it’s set to launch this December, and its overall budget has ballooned to $9.7 billion. Another space observatory that NASA is currently working on, the Nancy Grace Roman Space Telescope (formerly called WFIRST), also struggled with rising costs, so much so that the Trump administration tried to cancel the project. Both of these telescopes were considered the highest priority missions in previous decadal surveys.
The committee that penned the decadal report claims it’s making these recommendations with those lessons learned. For one, it argues that many of the technologies that were needed for JWST to work simply did not exist when the telescope was envisioned. “Doing that invention and technological maturation and testing and engineering — that just took a long time,” Stassun says. “And when things take a long time, they are expensive.” He’s hopeful that by getting started on the large telescope’s blueprints now, astronomers won’t be as blindsided by the technologies they’ll need to create.
Stassun also argues that the staggered development approach will allow mission planners to do check-ins from time to time to see how things are progressing. If one mission is ballooning out of control, then it can be paused or tweaked while the others stay in development. That way, there isn’t one mission that sucks up all the energy — and money — in the room the way that JWST did. Most of NASA’s astrophysics budget was dedicated to JWST during its most crucial development years, making it harder for small projects to get significant funding.
It might be a hard sell to Congress, which ultimately determines NASA’s budget and has been critical of JWST’s ballooning costs. But scientists are optimistic. NASA’s science budget has increased over the last few decades, and Gaudi thinks people will be inspired by what these future telescopes could tell us. “We have come to Congress and the American people saying, ‘Look, this is fantastic science that can answer the huge questions that are going to inspire generations to come,’” Gaudi says. “And it requires a modest increase in astrophysics development budget. I think we can make that case.”
The decadal survey calls for more than just building telescopes. The authors want to ensure that the people who are working on these projects are being protected. The report calls for a diversity and inclusion strategy for these missions, one that would make harassment and discrimination a form of scientific misconduct — a potentially career-ending move. And they also want the mission teams to be more mindful of how their work impacts indigenous communities and the environment. For instance, the authors suggest astronomers embrace remote conferencing long-term to decrease their carbon emissions from flying.
There’s a long road ahead to turn these dreams into reality. But for now, astronomers are excited for what looks like a bright future. “We stand at the threshold of a new golden era of discovery, both on the ground and in space: might we actually find evidence for life on another planet?” Hammel says. “This report — true to its name — lays out robust pathways to answer this question, and we can be the generation that answers it.”