About 20 years from now astronomers will be in the midst of a revolutionary era of discovery, using new telescopes on the ground and in space to study the cradle-to-grave evolution of galaxies, probe the deepest origins of black holes, glimpse the earliest moments of cosmic time and gather breakthrough images of Earth-like worlds orbiting other stars. On average, those future researchers should also be healthier and happier, more diverse and inclusive, than their present-day counterparts.
At least, that is the plan, according to the long-awaited major report “Pathways to Discovery in Astronomy and Astrophysics for the 2020s.” Also known as Astro2020, it is the seventh iteration of a once-every-10-years “Decadal Survey” process for astronomy conducted by the National Academies of Sciences, Engineering, and Medicine. Its overarching purpose is twofold: to codify communal consensus on the future of the field via a ranked list of research priorities and, perhaps more important, to muster vigorous support from federal policy makers for sustaining the broader enterprise of U.S. astronomy.
In pursuit of those goals, this latest Decadal Survey deviates sharply from its predecessors, which traditionally reserved their highest recommendations for specific new telescopes that were tightly bound to a small slice of the electromagnetic spectrum. Instead Astro2020’s highest space-based recommendation envisions a fundamental shift in the way that NASA plans and develops large, multibillion-dollar “flagship” astronomy projects. Dubbed the Great Observatories Mission and Technology Maturation Program, the initiative would invest $1.2 billion in the 2020s toward key enabling technologies for multiple proposed facilities in hopes of lowering the overall cost and risk associated with building and launching an entire fleet of next-generation telescopes to work together across a wide range of wavelengths, from infrared to x-rays.
The need for better management of NASA’s future astrophysical mega projects is particularly urgent, given missteps in handling those of the present and recent past. The James Webb Space Telescope—the top flagship recommendation of the first Decadal Survey of the new millennium—finally launched in late 2021 after a series of near-catastrophic multibillion-dollar budget overruns and agonizing schedule slips. The top recommendation from the Decadal Survey of 2010, the Nancy Grace Roman Space Telescope, fared somewhat better but has still suffered costly setbacks that delayed its launch until circa 2027.
The premier result of Astro2020’s top-recommended new program would be a supersize and far more sophisticated successor to the Hubble Space Telescope, which itself was the first in NASA’s sequence of four “Great Observatories” sent aloft between 1990 and 2003. Like Hubble, it would operate in optical, infrared and ultraviolet wavelengths, but it would be perhaps three times larger than that storied observatory and built for an estimated $11 billion. Beginning development at the end of this decade for a notional launch in the mid-2040s, it would snap pictures of dozens of potentially habitable exoplanets and study their atmospheres for signs of life while also being a workhorse for a wealth of traNSFormative astrophysics. Although it has no catchy formal name as of yet, astronomers are already referring to this project as “LuvEx,” referencing two progenitor telescope concepts—LUVOIR (Large Ultraviolet Optical Infrared Surveyor) and HabEx (Habitable Exoplanet Observatory)—that fed into its creation. In short order, it would be followed by two additional facilities, one focused on the far infrared and the other on x-rays, each built for a projected cost of $3 billion to $5 billion. These follow-on facilities also reflect two preexisting proposals: the far-infrared Origins telescope and the Lynx X-ray Observatory.
A Bright Future
“This report sets an ambitious, inspirational, and aspirational vision for the coming decade of astronomy and astrophysics,” said Fiona Harrison, a California Institute of Technology astronomer and co-chair of the Astro2020 steering committee, in a statement. “In changing how we plan for the most ambitious strategic space projects, we can develop a broad portfolio of missions to pursue visionary goals, such as searching for life on planets orbiting stars in our galactic neighborhood—and at the same time exploit the richness of 21st-century astrophysics through a panchromatic fleet.”
Many astronomers are understandably ecstatic. “I believe this is the smartest, most executable and pragmatic Decadal Survey ever written,” says John O’Meara, a vocal champion of the LUVOIR concept and chief scientist of the W. M. Keck Observatory on Mauna Kea in Hawaii. “The steering committee understood that we must redefine how we develop large missions so that we can realize this vision of new Great Observatories. They have brilliantly laid out how to achieve civilization-changing science in an uncertain world, and I hope NASA and other federal agencies embrace the spirit of the document.”
“We stand at the threshold of a new golden era of discovery,” says Heidi Hammel, vice president for science at the Association of Universities for Research in Astronomy. “Might we actually find evidence for life on another planet? This report, true to its name, lays out robust pathways to answer this question, and we can be the generation that answers it!”
Marc Postman, a distinguished astronomer at the Space Telescope Science Institute and a long-time proponent of large exoplanet-imaging observatories, holds a somewhat longer but no less gleeful view. “I’m walking on air right now because this is the culmination of a personal 15-year journey to get to this point. People ask me why I’ve spent time on this, because when [LuvEx] launches, I will certainly be retired but hopefully still in my mortal shell. I tell them I’m doing this for the future even if I never use it or see it get off the ground. And based on this Astro2020 report, the future is very bright. This is a generational initiative that is beyond any individual. Humanity is about to truly embark on a quest to learn whether we are alone in the universe.”
Besides the big-ticket item of a life-hunting telescope as the first of a line of flagship Great Observatories, Astro2020’s space-based recommendations also call for new once-per-decade “probe-class” missions with $1.5-billion cost caps, as well as significant spending to enhance astronomers’ abilities to study split-second celestial phenomena in real time using not only light but subatomic particles and gravitational waves as well.
Astro2020’s purview also extends to U.S. ground-based projects, which are typically funded and managed by the National Science Foundation (NSF) or occasionally by the Department of Energy. In this category, the report gives top ranking to a program to invest some $1.6 billion of NSF funding in the Giant Magellan Telescope (GMT) and the Thirty Meter Telescope (TMT), two gargantuan observatories in early phases of construction with an estimated total price tag in excess of $5 billion. With the GMT in the Southern Hemisphere, on a Chilean mountaintop, and the TMT in the Northern Hemisphere—either on the summit of Hawaii’s Mauna Kea or on a peak on La Palma in Spain’s Canary Islands—U.S. astronomers would gain profound new views of the entire sky through these extremely powerful telescopic eyes.
Other than helping these twin titans across the finish line, the report also recommends that the NSF and DOE jointly spend $660 million to create the Cosmic Microwave Background Stage 4 Observatory (CMB-S4), a facility to survey the big bang’s afterglow in exquisite detail. An additional $2.5 billion of NSF funds would go to building the Next-Generation Very Large Array (ngVLA), a radio observatory that would be 10 times more sensitive than the aging facilities it would replace. Additionally, Astro2020 strongly endorses further upgrades to two projects opening entirely novel windows on the cosmos: the Laser Interferometer Gravitational-wave Observatory (LIGO) and the IceCube Neutrino Observatory, a facility with thousands of detectors arranged within a cubic kilometer of Antarctic ice. Paired with traditional observatories, LIGO and IceCube can help astronomers divine the arcane mechanics at play within the cores of exploding suns and between merging black holes and neutron stars.
Power to the People
The pathway forward may be clear, but abundant obstacles remain. Much depends on whether Congress and the White House fully embrace—and fund—Astro2020’s recommendations, a not at all certain prospect in the modern era of hyperpolarized politics. Then there is the looming issue of satellite mega constellations. Despite their benefits for global broadband connectivity, these groups of satellites pose existential threats to multiple major projects via the optical and radio contamination they inescapably add to exquisitely delicate observations of the heavens. For that increasingly dire problem, Astro2020 offers only the rather dissatisfying solution of engaging in interagency, as well as international, collaboration to devise better, more protective regulatory frameworks.
But as the authors of the report themselves note, despite such challenges, the success of their audacious vision may ultimately hinge on how they handle the most valuable assets of U.S. astronomy, which are not dollars but people.
“Our report says serious attention also needs to be paid to investments in the foundations of this research—including in the people who carry it out,” said Astro2020 steering committee co-chair Robert Kennicutt, an astronomer who holds professorships at the University of Arizona and Texas A&M University, in a statement.
That recognition, deep in the Decadal Survey’s bones, is one reason Astro2020 is “a huge win for U.S. astronomy,” says Scott Gaudi, an astronomer at the Ohio State University and co-chair of the HabEx mission concept study. “The decadal steering committee really thought about how to create a balanced portfolio—not just with a new set of Great Observatories and projects like the GMT and TMT but also with significant support for basic things like more research grants and mid-scale programs. And that’s exactly what we need to make the more ambitious parts of this vision even plausible in the first place.”
In recent years the community has been left reeling not only from budget-blowing projects but also from sexual harassment scandals, anemic support for early-career researchers and their smaller-scale projects, and brutal asymmetries in work-life balance that have led to burnout and poor well-being. There is also a worrisome lack of diversity among the ranks. In this melting pot nation, the typical practitioners of astrophysics remain overwhelmingly white and male, with all the privileges, obvious or subtle, this entails—something keenly felt when, for instance, some of them seek to build new facilities on the sacred grounds of historically disenfranchised minority groups, as is the case of the TMT and the project’s preferred construction site on Mauna Kea.
To remedy these and other social ills, Astro2020 recommends more spending on research grants and independent postdoctoral fellowships, increased funding and institutional support for diversity-boosting initiatives at the university and federal agency levels, and a formal recognition at NASA, the NSF and the DOE that harassment and discrimination are corrosive forms of scientific misconduct. With the TMT imbroglio at Mauna Kea clearly in mind, the report also calls for a “Community Astronomy” model of engagement that would seek to “respect, empower, and benefit local communities while advancing scientific research,” according to a National Academies press release.
Such acts, says University of New Hampshire cosmologist Chanda Prescod-Weinstein, would be “steps in the right direction” to address the growing storm of cultural crisis cresting over the field’s horizons. But even so—especially in the case of engaging with historically marginalized Indigenous people—she says this Decadal Survey’s recommendations do not go far enough.
“Sometimes scientists have to accept a hard ‘no’ from Indigenous people,” Prescod-Weinstein says. “Instead [Astro2020] focuses more on what the characteristics and quality of a collaboration between Indigenous communities and scientists should be. It never directly acknowledges the scenario that Indigenous people may not want to collaborate.... My view may change once I’ve had more time to sit with the report, but my first impression is that scientific goals are still supreme and that we are still not ready, as a community, to talk to nonastronomer Indigenous people as if they are our equals and their concerns matter as much as ours.”