NASA publishes simulated universe previews from upcoming 'Roman' telescope

Astronomers have released a set of more than a million simulated images showcasing the cosmos "as NASA's upcoming Nancy Grace Roman Space Telescope ("Roman") will see it," says the statement from NASA. This preview will help scientists explore a myriad of the science goals of Roman, which is scheduled to launch into a Sun-Earth "L2" orbit by May 2027.

Roman is managed at NASA's Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA's Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a science team comprising scientists from various research institutions. Industrial partners include BAE Systems, L3Harris Technologies, and Teledyne Scientific & Imaging.

"We used a supercomputer to create a synthetic universe and simulated billions of years of evolution, tracing every photon's path all the way from each cosmic object to Roman's detectors," said Michael Troxel, an associate professor of physics at Duke University in Durham, North Carolina, who led the simulation campaign. "This is the largest, deepest, most realistic synthetic survey of a mock universe available today."

The project, called OpenUniverse, relied on the now-retired Theta supercomputer at the U.S. Department of Energy's Argonne National Laboratory in Illinois. The supercomputer accomplished a process that would take over 6,000 years on a typical computer in just nine days.

In addition to Roman, the 400-terabyte dataset will also preview observations from the Vera C. Rubin Observatory, which is jointly funded by the National Science Foundation and the U.S. Department of Energy, and approximate simulations from the European Space Agency's Euclid mission, which has NASA contributions. The Roman data is available now here, and the Rubin and Euclid data will soon follow.

'Look back 12 billion years'

The team used the most sophisticated modeling of the universe's underlying physics available and fed in information from existing galaxy catalogs and the performance of the telescopes' instruments. The resulting simulated images span 70 square degrees, equivalent to an area of sky covered by more than 300 full moons. In addition to covering a broad area, it also covers a large span of time - more than 12 billion years.

The project's immense space-time coverage shows scientists how the telescopes will help them explore some of the biggest cosmic mysteries. They will be able to study how dark energy and dark matter shape the cosmos and affect its fate.

Scientists will also be ale to get closer to understanding dark matter by studying its gravitational effects on visible matter. And by studying the simulation's 100 million synthetic galaxies, they will see how galaxies and galaxy clusters evolved over eons. Repeated mock observations of a particular slice of the universe enabled the team to stitch together movies that unveil exploding stars crackling across the synthetic cosmos like fireworks.

Scientists are already using OpenUniverse data as a testbed for creating an alert system to notify astronomers when Roman sees such phenomena. The system will flag these events and track the light they generate so astronomers can study them. This is necessary because Roman will send back far too much data for scientists to comb through themselves.

"Most of the difficulty is in figuring out whether what you saw was a special type of supernova that we can use to map how the universe is expanding, or something that is almost identical but useless for that goal," said Alina Kiessling, a research scientist at NASA's Jet Propulsion Laboratory in Southern California and the principal investigator of OpenUniverse.

While Euclid is already actively scanning the cosmos, Rubin is set to begin operations late this year and Roman will launch by May 2027. Scientists can use the synthetic images to plan the upcoming telescopes' observations and prepare to handle their data. This prep time is crucial because of the flood of data these telescopes will provide.

In terms of data volume, "Roman is going to blow away everything that's been done from space in infrared and optical wavelengths before," Troxel said. "For one of Roman's surveys, it will take less than a year to do observations that would take the Hubble or James Webb space telescopes around a thousand years. The sheer number of objects Roman will sharply image will be transformative."