New era of 'Great Observatories' may be coming for NASA

A view of the Hubble Space Telescope in orbit. Hubble is one of NASA's four "Great Observatories," which launched between 1990 and 2003. The agency has been urged to start a new Great Observatories program, to help get big, powerful space telescopes off the ground more efficiently.
A view of the Hubble Space Telescope in orbit. Hubble is one of NASA's four "Great Observatories," which launched between 1990 and 2003. The agency has been urged to start a new Great Observatories program, to help get big, powerful space telescopes off the ground more efficiently. (Image credit: NASA)

A new "Great Observatory" era may be just around the bend.

On Thursday (Nov. 4), the U.S. National Academies of Sciences, Engineering, and Medicine released its highly anticipated astronomy and astrophysics decadal survey, which lays out scientific priorities and funding recommendations for the next 10 years in those two related fields.

One of the top priorities identified in the 614-page report is the establishment of a "Great Observatories Mission and Technology Maturation Program," which would help NASA get big, powerful space telescopes off the ground more quickly and efficiently.

The new program "is aimed at increasing the cadence of large missions by designating appropriate scope at an early stage and making significant investments in maturing missions to the appropriate level prior to ultimate recommendation and implementation," the survey states.

Ideally, the program would result in the overlapping operation of a diverse set of highly capable space telescopes. This would allow astronomers to study cosmic objects and phenomena in great detail and depth — a vision that NASA achieved with its original Great Observatories program several decades ago.

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Four Great Observatories

The four original Great Observatories were the roughly $10 billion (in 2020 dollars) Hubble Space Telescope, which views the heavens mainly in visible and ultraviolet light; the $1.2 billion Compton Gamma-Ray Observatory and the $3.1 billion Chandra X-ray Observatory, whose specialties are indicated by their names; and the $1 billion Spitzer Space Telescope, which was optimized to observe in low-energy infrared light.

NASA launched all four of these scopes between 1990 and 2003, pulling off a cadence that seems especially impressive in retrospect. After all, it has taken more than two decades to develop the $10 billion James Webb Space Telescope, which NASA bills as Hubble's successor. (Webb is finally nearing the finish line; it's scheduled to launch from French Guiana on Dec. 18.)

The four Great Observatories worked quite well together. Hubble and Spitzer were frequent partners on exoplanet studies, for example; astronomers used data from both scopes to determine that the atmospheres of "hot Jupiters" are surprisingly dry, among other finds. 

(The past tense is not entirely appropriate here, by the way. While Compton and Spitzer are no longer with us, Hubble and Chandra are still going strong — though Hubble is dealing with a glitch at the moment.)

The original Great Observatory mission suite demonstrated the "power of broad wavelength coverage" and sets a good example for NASA to follow in the next decade and beyond, according to the new survey.

"This was an extremely successful model that propelled major scientific advances on broad fronts over the course of two decades or more," the report states. "The survey committee believes that it is scientifically compelling to replicate this approach today."

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First up: A big exoplanet-studying space telescope

The survey also identifies what it thinks should be the first mission in the new Great Observatories program: an infrared/optical/ultraviolet (IR/O/UV) space telescope with a primary mirror about 19.7 feet (6 meters) wide. For comparison, Hubble's main mirror is 7.9 feet (2.4 m) wide, and Webb's is 21.5 feet (6.4 m) across. 

The proposed new scope would be optimized for studying habitable exoplanets — scanning their atmospheres for possible biosignatures, for example — and making general astrophysics observations. The new observatory could be developed for about $11 billion and be ready for launch by the early 2040s, the survey determined.

The report further recommends that, five years after beginning work on the IR/O/UV telescope, NASA should start developing both a far-IR mission and an X-ray mission.

Each of these following two missions should have "a target scope of between $3 and $5 billion and the goal, therefore, of being able to develop rapidly by the start of next decade," Fiona Harrison, co-chair of the National Academies' steering committee for the survey, said during a news conference on Thursday.

"I think if we can really achieve this new paradigm for developing large strategic missions at NASA, that really has the potential to be transformative, because we can sort of plan and develop them more coherently [and] increase the launch rate of very important capabilities over a wide range of wavelengths," added Harrison, who chairs the division of physics, mathematics and astronomy at the California Institute of Technology in Pasadena.

The decadal survey makes recommendations, not rules, so there's no guarantee that the new Great Observatories program will come to be. But the odds are decent, given the track record of high-priority items identified in other decadals.

For example, the 2001 survey flagged Webb — then known as the Next Generation Space Telescope — as the highest-priority mission to develop over the next 10 years. And the 2010 report highlighted the Wide-Field Infrared Survey Telescope (WFIRST) and the Large Synoptic Survey Telescope (LSST) as especially important projects. WFIRST, now called the Nancy Grace Roman Space Telescope, is slated to launch no later than May 2027, and the ground-based LSST, now known as the Vera C. Rubin Observatory, will open its eyes on a Chilean mountaintop a year or so from now, if all goes according to plan.

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook

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Mike Wall
Senior Space Writer

Michael Wall is a Senior Space Writer with and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.