Roman Scientists Describe a Telescope Built to Find What We Do Not Expect
Before the Nancy Grace Roman Space Telescope launched, NASA gathered a panel of mission experts at Kennedy Space Center to explain what the observatory was designed to do once it reached space. The conversation looked beyond the launch itself, focusing on the questions Roman will investigate, the technologies it will test, and the enormous volume of data it will make available to scientists and the public.
The science briefing featured Sean Domingo Goldman, director of NASA’s Astrophysics Division; Julie McEnry, Roman senior project scientist; Vanessa Bailey, Roman Coronagraph Instrument scientist; Kristen McQuinn, Roman Science Operations Center lead; and Lee Armas, Roman Science Support Center lead scientist. Together, they described an observatory built not only to examine some of astronomy’s largest unanswered questions, but also to uncover phenomena scientists have not yet anticipated.
A Wider View of the Universe
Roman combines the precision associated with the Hubble Space Telescope with a field of view more than 100 times larger. According to the panel, it will be able to survey the sky roughly 1,000 times faster than Hubble. McEnry explained that a survey Roman could complete in one month would take Hubble approximately a century. That speed and reach will allow Roman to study the universe on a scale that has not previously been possible. Its surveys will examine billions of galaxies, monitor hundreds of millions of stars, detect tens of thousands of supernovae, and build a much larger census of planets beyond our solar system.
Roman’s surveys will:
Examine billions of galaxies
Monitor hundreds of millions of stars
Detect tens of thousands of supernovae
Build a much larger census of exoplanets
The panel emphasized that Roman is not simply intended to perform the same science as Hubble more quickly. Its broad view will allow researchers to examine how galaxies and other large-scale structures formed and changed over time. By measuring both the distribution of matter and the expansion of the universe, scientists hope to better understand dark matter and dark energy—two major components of the universe that remain poorly understood.
Roman will also repeatedly observe large regions of the sky, giving scientists a better opportunity to detect short-lived events. These may include exploding stars, stellar flares, stars disrupted by supermassive black holes, and the aftermath of neutron-star collisions. Because many such events appear and fade quickly, Roman’s ability to monitor wide areas over time will be especially important.
Expanding the Search for Other Worlds
Roman will search for exoplanets using both transit observations and gravitational microlensing. The transit method detects the slight dimming that occurs when a planet passes in front of its star. The panel estimated that Roman could identify as many as 100,000 new transiting planets.
Microlensing offers a different view. When a foreground star passes in front of a more distant star, its gravity bends and magnifies the background starlight. A planet orbiting the foreground star can create an additional change in that light. Roman’s microlensing survey is expected to find thousands of planets, including worlds located farther from their stars than those most commonly detected through transit surveys. It may also identify free-floating planets and isolated black holes.
Sean Domingo Goldman explained that this difference matters because previous detection methods have generally favored planets orbiting close to their stars. Roman’s microlensing observations will help scientists examine the more distant portions of planetary systems, including the outer regions of habitable zones, and develop a more complete picture of how common different types of planets may be.
A Stepping Stone Toward Imaging Earth-Like Planets
Roman’s second instrument, the Coronagraph Instrument, will demonstrate technologies needed to photograph faint planets beside much brighter stars. Bailey compared the challenge to trying to see a firefly next to a lighthouse hundreds of miles away.
“It’s like trying to see a firefly next to a lighthouse hundreds of miles away.” Bailey states.
The instrument will block a star’s light and use deformable mirrors to correct tiny optical imperfections that would otherwise create glare. Those mirrors can be adjusted with precision approaching the scale of an atom. The goal is to detect planets approximately 100 million times fainter than their stars—a major improvement over current capabilities and an intermediate step toward eventually imaging Earth-like planets.
The coronagraph will primarily study planets that have already been detected through other methods rather than conduct a broad, blind search. Because preparing the instrument for an observation requires a lengthy process of tuning and correction, the team plans to point it toward systems where a planet is already expected. Scientists can then study visible light reflected from those planets and look for information about their atmospheres. The instrument will also observe debris disks and asteroid belts for clues about how planetary systems form and evolve.
Making Roman’s Data Available to Everyone
Roman’s scientific reach will create a practical challenge: how to process and use an extraordinary amount of information. The mission is expected to produce about 20,000 terabytes of data during its operations, including thousands of images processed each day.
McQuinn and Armas described a cloud-based system designed to process, archive, and distribute those observations. Instead of requiring researchers to download massive datasets, the Roman Research Nexus will allow them to work with the information in the cloud. Raw and calibrated data will enter through a common access point, while processing teams will create science-ready images, spectra, and other products.
The data will not have a proprietary period. Students, professional researchers, educators, and members of the public will be able to access it at the same time. McQuinn noted that a high-school classroom could work with new Roman observations alongside researchers at major institutions. Tutorials, shared accounts, and prepared workflows are intended to help people do more than simply locate the data; they are meant to make meaningful analysis possible.
The mission will also periodically reprocess earlier observations as calibration methods and algorithms improve. These enhanced releases should produce more consistent datasets and may lead to new waves of discoveries throughout Roman’s five-year primary mission.
Discoveries Expected (and Unexpected)
The panel cautioned that Roman’s biggest cosmological findings will take time. Early observations may quickly produce discoveries involving exoplanets, transient events, and small galaxies, but precise measurements of dark energy and the evolution of the universe will require larger datasets, extensive calibration, and years of analysis.
Still, the speakers repeatedly returned to Roman’s potential to reveal something no one had thought to look for. Its combination of sensitivity, speed, repeated observations, and open access will give scientists an unprecedented view of a changing universe.
As McEnry explained during the briefing, “The most exciting science is going to be the thing that you didn’t expect.” Roman was designed to investigate questions already central to modern astronomy. Its greater promise may be the new questions that emerge once it begins showing the universe in a way we have never seen before.
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