NASA's Nancy Grace Roman Space Telescope is fully assembled and on track for a September 2026 launch, eight months ahead of schedule, with a science mission expected to dwarf any previous observatory.
NASA's Nancy Grace Roman Space Telescope is ready to launch. What's more, it's doing so eight months ahead of schedule and under budget, which in space terms is something close to miraculous. All being well, the fully assembled observatory will launch in September 2026 on a SpaceX Falcon Heavy.
NASA expects Roman to unveil more than 100,000 distant worlds, hundreds of millions of stars, and billions of galaxies during its primary mission, potentially making it the single biggest contributor to astronomical data ever conceived.
Named after Nancy Roman, the pioneering first female executive at NASA who served as its first Chief of Astronomy throughout the 1960s and 1970s, the Roman Space Telescope is a next-generation observatory designed to survey the infrared universe.
The telescope has an unusual origin. In 2012, the National Reconnaissance Office offered NASA two surplus spy satellite mirrors, each 2.4 m (7.9 ft) across, roughly the same aperture as Hubble but with a shorter focal length and wider field of view. NASA had already been developing WFIRST (the Wide Field Infrared Survey Telescope) around a 1.5 m primary, but decided the switch was worthwhile. Adopting the larger NRO hardware meant scaling up much of the surrounding architecture, but it also delivered higher-resolution imaging and more room for science instruments.
Roman is an observatory optimized for survey work on a scale no previous space telescope has attempted. Its Wide Field Instrument combines 18 detectors, each 4096 x 4096 pixels, to cover a patch of sky roughly 100 times larger than Hubble's widest images (about the apparent size of a full Moon).
That generates 1.4 terabytes of data per day. NASA senior project scientist Julie McEnery offered a sense of scale at a press conference announcing the potential launch date, saying that to display a full Roman survey image at single-pixel resolution on 4K monitors would require enough screens to cover the face of El Capitan in Yosemite.
A filter carousel allows the instrument to work across multiple infrared bands. It also carries a prism and a grism for spectroscopic observation, enabling Roman to measure both the composition of light sources and the redshift of distant objects.
The second instrument is the first space-based coronagraph. This features active optical elements that can block out the light from a star in the center of the field of view to allow direct imaging of exoplanets in wide orbits.
Roman will also conduct a microlensing survey of the galactic bulge, observing the same fields every 15 minutes to catch the brief brightening events that betray the presence of a planet crossing a background star. The expectation is tens of thousands of planet detections, including so-called rogue planets that have been ejected from their original systems.
Compared to the long, drawn-out and high-stakes drama that was the deployment of the James Webb Space Telescope over weeks, Roman carries relatively few deployable components. Solar arrays and the high-gain antenna are spring-loaded and should open within 20 minutes of separation from the launch vehicle. Commissioning is planned for 90 days, and the telescope may begin science operations even before completing its final burn into the Sun-Earth L2 Lagrange point.
Having got used to the longevity of an instrument like Hubble, which has been in orbit for over 36 years, the 10-year predicted lifespan of Roman is a bit of a surprise. Fuel load is the primary constraint on mission life, but that 10 years is a conservative estimate and there is hope that it might be able to carry on its science mission a considerable way beyond the projected completion.