Roman space telescope passes key construction milestone ahead of launch window

by Clarence Oxford
Los Angeles CA (SPX) Dec 05, 2025

NASA has completed assembly of the Nancy Grace Roman Space Telescope, joining the inner and outer sections of the observatory in the largest clean room at the agency's Goddard Space Flight Center in Greenbelt, Maryland, on Nov. 25, 2025. The mission is scheduled to launch no later than May 2027, with teams currently working to be ready for a launch opportunity as early as fall 2026 on a SpaceX Falcon Heavy rocket from NASA's Kennedy Space Center in Florida. After final environmental and performance testing, the spacecraft will ship to Kennedy in mid 2026 and then head to an operational orbit about one million miles from Earth.

NASA officials describe completion of the observatory as a major step toward a mission designed to address fundamental questions about the universe. "Completing the Roman observatory brings us to a defining moment for the agency," said NASA Associate Administrator Amit Kshatriya. "Transformative science depends on disciplined engineering, and this team has delivered - piece by piece, test by test - an observatory that will expand our understanding of the universe. As Roman moves into its final stage of testing following integration, we are focused on executing with precision and preparing for a successful launch on behalf of the global scientific community."

Roman is optimized for infrared observations, detecting light at wavelengths longer than the human eye can see to study objects from the solar system to near the edge of the observable universe. NASA plans a five year primary mission during which Roman will survey wide areas of the sky to investigate dark energy, dark matter, exoplanets, stellar populations, galaxies, and compact objects such as isolated black holes. Nicky Fox, associate administrator for NASA's Science Mission Directorate, said the mission is tailored to probe why the expansion of the universe appears to be accelerating and to explore something fundamental about space and time that remains unexplained.

"With Roman's construction complete, we are poised at the brink of unfathomable scientific discovery," said Julie McEnery, Roman's senior project scientist at NASA Goddard. "In the mission's first five years, it's expected to unveil more than 100,000 distant worlds, hundreds of millions of stars, and billions of galaxies. We stand to learn a tremendous amount of new information about the universe very rapidly after Roman launches." Roman's large field of view and sensitivity are designed to return vast imaging and spectroscopic datasets that will support multiple science programs simultaneously.

The observatory carries two instruments: the Wide Field Instrument and the Coronagraph Instrument technology demonstration. The coronagraph is built to block starlight and directly image planets and dusty disks around nearby stars in visible light, targeting older, colder, giant planets in closer orbits than those primarily detected so far with direct imaging. "The question of 'Are we alone?' is a big one, and it's an equally big task to build tools that can help us answer it," said Feng Zhao, the Roman Coronagraph Instrument manager at NASA's Jet Propulsion Laboratory in Southern California. "The Roman Coronagraph is going to bring us one step closer to that goal. It's incredible that we have the opportunity to test this hardware in space on such a powerful observatory as Roman."

During Roman's first 18 months of operations, the coronagraph team will carry out a pre planned set of observations spanning roughly three months of telescope time to evaluate the instrument's performance. Further coronagraph use may follow based on feedback and proposals from the wider scientific community. The Wide Field Instrument, a 288 megapixel camera, will capture images covering areas of sky larger than the apparent size of the full Moon in each exposure and is expected to collect about 20,000 terabytes of data over the primary mission, far exceeding the data volume returned by the Hubble Space Telescope.

Roman's observing plan allocates about 75% of the primary mission to three core surveys. The High Latitude Wide Area Survey will combine imaging and spectroscopy to map more than a billion galaxies, tracing how structure forms and evolves and providing measurements that will help constrain dark matter and the growth of galaxy clusters over cosmic time. The High Latitude Time Domain Survey will repeatedly monitor the same regions to build time series datasets, enabling studies of variable and transient phenomena and providing independent constraints on dark energy by tracking how cosmic expansion changes with time.

Roman's Galactic Bulge Time Domain Survey will target the central regions of the Milky Way to monitor hundreds of millions of stars and search for microlensing events caused by intervening stars, planets, and compact objects. This survey will probe planets in and beyond the habitable zones of their host stars, including analogs of the outer planets in the solar system, and detect free floating rogue planets that do not orbit stars as well as isolated black holes. The same observations are predicted to reveal about 100,000 transiting exoplanets that pass in front of their stars, broadening Roman's exoplanet census.

The remaining 25% of the mission will support competitively selected observing programs proposed by the scientific community, beginning with a Galactic Plane Survey that has already been chosen as the first such investigation. A General Investigator Program will enable astronomers worldwide to request Roman observations or analyze archival data, with NASA planning to release all mission data without an exclusive use period so that multiple teams can pursue different science questions from the same datasets. Mission managers expect that the breadth of the surveys and open data policy will yield discoveries well beyond the core dark energy and exoplanet goals.

The telescope is named for Dr. Nancy Grace Roman, NASA's first chief astronomer, who championed early space based observatories and played a central role in making space astronomy a core part of the agency's science program. "The mission will acquire enormous quantities of astronomical imagery that will permit scientists to make groundbreaking discoveries for decades to come, honoring Dr. Roman's legacy in promoting scientific tools for the broader community," said Jackie Townsend, Roman's deputy project manager at NASA Goddard. Roman's project team includes NASA's Goddard Space Flight Center and Jet Propulsion Laboratory, Caltech/IPAC in Pasadena, the Space Telescope Science Institute in Baltimore, a distributed science team, and industrial partners BAE Systems Inc., L3Harris Technologies, and Teledyne Scientific and Imaging.