Roman Space Telescope completes key Instrument alignment

NASA’s Nancy Grace Roman Space Telescope completed instrument alignment work on Nov. 13, 2026, clearing a key milestone toward science operations. Roman must remain at least ten times more stable than Hubble or Webb to conduct its planned science, said Dominic Benford, Roman’s program scientist at NASA Headquarters in Washington. The requirement is central to the telescope’s dark-energy and exoplanet-imaging objectives. “Roman requires exquisite alignment because it has to be at least ten times more stable than our Hubble or Webb space telescopes,” Benford said. Before launch, Roman’s team lined up the observatory’s optics and instruments on the ground, but shaking during liftoff, temperature changes, and the absence of gravity in space can cause small movements in orbit. Scientists compare observed star positions with expected positions to update Roman’s “internal map,” keeping the telescope pointed correctly. Tony Sohn, an astronomer at the Space Telescope Science Institute, said the alignment reaches a tiny fraction of a hair’s breadth of perfection, essential for pointing and holding still during observations. The Wide Field Instrument’s 18 detectors must work together when Roman locks onto guide stars, said Tyler Desjardins, an astrophysicist at the Space Telescope Science Institute in Baltimore. Precise guide star positions allow accurate aiming and correction of tiny drifts. The Wide Field Instrument doubles as Roman’s primary instrument and guider, tracking stars to keep the observatory pointed and steady while the Coronagraph Instrument images nearby stars for planets and dusty disks in an adjacent patch of sky. Bonus deep fields from those neighboring patches will come at no extra cost, Benford said. To prepare the coronagraph, Roman’s team moved the secondary mirror, a smaller mirror linking the telescope to the Coronagraph Instrument, and every mask and optic inside the instrument itself. Brian Kern, an optical engineer at NASA’s Jet Propulsion Laboratory in Southern California, said starlight spills into areas where planets could be found because of the wave nature of light, and coronagraph masks absorb and redirect that spilled light. The next step is to exercise more than 3,000 small moving parts that drive the coronagraph’s deformable mirrors. Lab tests with an artificial space environment showed how the mirrors control starlight, but using real starlight and real planets in space will be a record-breaking first-time accomplishment. On October 17, 2026, engineers reported that after precision adjustments, Roman’s Wide Field Instrument produces image quality nearly 30% better than predicted. Engineers had set a pre-launch image quality requirement of approximately 90 nanometers RMS, and after corrections they measured an optical error of just 63 nanometers RMS. Ninety nanometers is about 1,000 times thinner than a human hair. On October 17, 2026, engineers moved Roman’s secondary mirror by about one-sixteenth of the diameter of a human hair to improve alignment, said Alden Jurling, a senior optical engineer at NASA Goddard. Matthew Bolcar, Roman’s optical systems lead at NASA Goddard, said the mirrors were already well aligned before launch, so engineers needed only minor corrections after ground preparation and testing by Goddard and contractors L3Harris and BAE Space and Mission Systems. Following activation of the Wide Field Instrument in September 2026, engineers tested its 18 detectors, each about the size of a sticky note, along with the electronics that run them. They checked the element wheel carrying filters and other optical parts, turned on the internal calibration system’s LEDs, moved the alignment mechanism out of its deliberately unfocused launch position, and verified the thermal control system. Maxime Rizzo, a Wide Field Instrument systems engineer at NASA Goddard, compared the work to tuning a piano or guitar before a concert. On October 17, 2026, the team initially concentrated on the Coronagraph Instrument, which had been producing slightly out-of-focus images, a problem less severe than anticipated. Engineers corrected the coronagraph focus relatively straightforwardly, then returned to the Wide Field Instrument for another round of adjustments. The team will test the coronagraph’s ability to block stray light in the coming weeks, checking whether it can keep illumination away from faint targets beside bright stars. Both scientific instruments now meet or surpass expected performance, clearing another important milestone in preparation for routine observations. Roman launched on Aug. 30, 2026, aboard a SpaceX Falcon Heavy rocket from Kennedy Space Center under a $255 million NASA Launch Services II contract. The 4.2-metric-ton observatory with a 2.4-meter primary mirror matching Hubble’s aperture carries active thermal isolation systems to keep its focal plane and optical train at cryogenic temperatures near Sun-Earth Lagrange Point 2, about one million miles from Earth. After orbital insertion, Roman will execute a three-month transit to L2, enter a halo orbit, and perform three months of calibration, cooling, and alignment before primary science. Nancy Grace Roman Space Telescope, formerly known as WFIRST, was designated by the National Academies’ Decadal Survey as the top-priority large space mission for astrophysics. Roman’s primary scientific objectives focus on dark energy dynamics, dark matter distribution, and exoplanet demographics through a five-year baseline mission. Its Wide Field Instrument uses a 300-megapixel focal plane array with 18 specialized detectors measuring infrared light across wavelengths from 0.48 to 2.3 microns. The instrument’s field of view is 100 times larger than Hubble’s while surveying the sky more than 1,000 times faster, and the Coronagraph Instrument suppresses host star glare by a factor of one billion. “All of Roman’s sweeping surveys will rely on the Wide Field Instrument,” said Dave Hickey, a Wide Field Instrument systems engineer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, adding that goals such as studying dark matter and dark energy could not be achieved without it. Measurements of the universe’s expansion and cosmic structure growth have produced tensions with current predictions, which Roman may help resolve by surveying billions of galaxies and supernovae using weak gravitational lensing, baryon acoustic oscillations, and Type Ia supernovae. If discrepancies are confirmed, researchers might need to consider evolving dark energy or a basic change in how gravity operates on the biggest scales. Roman will search for planets using the transit method and gravitational microlensing, which can find planets farther from their stars than transit surveys, including Earth-sized planets in outer habitable zones. Its microlensing survey will monitor 200 million stars in the inner Milky Way, and the method could also turn up rogue planets drifting through the galaxy and isolated black holes and neutron stars. The coronagraph will demonstrate technology that might eventually make imaging an Earth twin possible, though it is not intended to photograph an Earth twin itself; researchers expect direct images of Jupiter-like planets and studies of dusty debris disks around stars. Roman will work alongside Hubble and Webb rather than replace them, with Roman’s surveys locating unusual targets for the older telescopes to follow up in detail. “Roman doesn’t do Hubble science faster,” said Julie McEnery, Roman’s senior project scientist, on Aug. 29, 2026. NASA is also creating a cloud-based system that lets scientists work directly with Roman’s observations instead of downloading the whole archive; the data will be open to the public with no exclusive period, and groups including students can analyze the observations together. McEnery said she hopes and expects that Roman’s most exciting science will turn out to be a surprise.