Nancy Grace Roman Space Telescope

Nancy Grace Roman Space Telescope, U.S. satellite observatory designed to investigate dark energy, dark matter, and exoplanets. The telescope carries a primary mirror 2.4 meters (7.9 feet) in diameter and two scientific instruments: the Wide Field Instrument (WFI) and the Roman Coronagraph Instrument. The WFI will give the telescope a field of view over a hundred times larger than that of the Hubble Space Telescope (HST), and the coronagraph will enable it to directly image Jupiter-size exoplanets. The telescope is named for NASA’s first chief of astronomy, Nancy Grace Roman, who is known as the “Mother of Hubble” for her instrumental role in the creation of the HST. It was launched by a SpaceX Falcon Heavy rocket from the Kennedy Space Center in Florida on August 30, 2026.

The telescope will gather data on how dark energy and dark matter have influenced galaxies over billions of years by tracking the movement and clustering of galaxies over various phases in the universe’s history. This capability is a product of two sources: the telescope’s large field of view, which can capture millions of galaxies in a single image, and the ability of powerful telescopes to peer back in time. Because light from distant galaxies can take billions of years to reach Earth, these telescopes see these galaxies as they appeared billions of years ago. These large-scale surveys will help scientists understand how dark energy and dark matter have shaped the universe’s evolution.

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The telescope will also shed light on how common Earth-like planets are in the Milky Way Galaxy by expanding scientists’ survey of exoplanets. Previous exoplanet detection methods, such as the transit method, struggle to detect planets far from their host stars (the transit method relies on exoplanets passing in front of their stars so that they block a small amount of light). The telescope will use gravitational microlensing to detect planets in and beyond the habitable zones of their star systems. An exoplanet’s gravity can bend the light of background stars as the exoplanet passes in front of them. This focuses the star’s light onto Earth like the lens of a giant magnifying glass, resulting in small increases in the brightness of stars as seen through telescopes. With a representative sample of exoplanets in the galaxy, scientists can more accurately determine whether planets like Earth are rare or plentiful.

Proposed as a top-priority space observatory in a 2010 decadal report by the National Academy of Sciences, the Roman Space Telescope was known as the Wide Field Infrared Survey Telescope until 2020. Although the original proposal had been for the telescope to carry a primary mirror 1.5 meters (4.9 feet) in diameter, the telescope’s design was revised to carry a 2.4-meter (7.9-foot) mirror instead when the National Reconnaissance Office donated two of those mirrors to NASA in 2012.