NASA’s Roman Space Telescope Enters Final Commissioning Phase

NASA's Nancy Grace Roman Space Telescope mission has now entered the science commissioning phase, having successfully completed a comprehensive checkout and refinement of the observatory and primary instrument performance.

"We've established that the observatory is fully functional," said Julie McEnery, Roman's senior project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The telescope can guide and take exposures, data flows appropriately, and we can slew from one place to another for observations. So now we're drilling into the fine details of the quality of the images we're collecting."

Thus far, the commissioning process is going smoothly, and the observatory has already undergone several challenging activities. For example, scientists thought Roman might have difficulty observing places that are both chock full of stars, or nebulae that are shrouded by dense dust.

"The way Roman locks onto a target is by holding steady on individual stars found in the direction it needs to point," said Tom Barclay, Roman operations project scientist at NASA Goddard. "We had a concern that in regions where stars are either packed extremely close together or embedded in thick dust, the fine guidance system might get confused or have trouble staying tethered to those stars. But test observations of such regions have shown that Roman performs wonderfully in all cases."

Roman's observing requirements are extraordinarily stringent. Multiple factors can influence the consistency of a telescope's images. If some images were blurrier or brighter than others, it would be difficult to determine whether cosmic objects were truly changing or just appeared to differ because of effects intrinsic to the telescope.

"To achieve the groundbreaking science we expect from Roman, we need to have a crystal clear window into space, not one marred by pointing jitter or out-of-focus images," said Josh Schlieder, Roman's Wide Field Instrument scientist at NASA Goddard. "Any imperfections that affect image quality must be minimized because even very small flaws could mask the small signals we are aiming to measure."

Now, the team is performing a series of carefully planned test observations that will allow them to characterize observatory performance, calibrate how the instruments respond to light, and refine the telescope's image quality before transitioning to science operations. The mission's initial test observations have gone so well that the team is beginning to experience Roman's superpower: speed.

"During commissioning, we are taking several test observations of famous parts of the sky," said Jeremy Perkins, an astrophysicist serving as Roman's observatory integration and test scientist at NASA Goddard. "I am marveling at the level of detail Roman provides in very short time periods."

Fast survey speeds translate to enormous cosmic vistas, each packed with planets, stars, and galaxies galore. Large mosaics that used to be reserved for special occasions will soon become routine, and rare sightings will become customary.

"In a typical observation with Roman's Wide Field Instrument, we'll see objects that are a hundred million times fainter than the human eye can detect," Schlieder said. "So just imagine what strange and unexpected things might be buried in all that data."

Fine-tuning Roman's image detail during science commissioning will help scientists more fully understand what to expect. Since some of the observatory's systems are performing even better than required, it could open up new scientific capabilities, adding even more to the data deluge the mission will return.

To learn more about Roman's commissioning process, visit:

science.nasa.gov/missions/roman-space-telescope/roman-commissioning