NASA's Nancy Grace Roman Space Telescope is producing sharper images than its team expected. On October 14, 2026, NASA said the observatory's main instrument passed its checkouts and the telescope's focus had been fine-tuned, leaving the Wide Field Instrument performing nearly 30% better than predicted.
Roman launched on August 30, 2026.
The numbers
The image-quality requirement for the Wide Field Instrument was about 90 nanometers RMS (root mean square). That means the optics can deviate from perfection by no more than 90 nanometers, which NASA says is about 1,000 times thinner than a human hair.
After corrections, NASA says the instrument's optics have an error of just 63 nanometers RMS.
"All of the images from Roman's cosmic surveys will be even sharper than we expected," said Alden Jurling, a senior optical engineer on Roman at NASA's Goddard Space Flight Center.
A very small adjustment
NASA says the optics arrived in space nearly perfectly aligned, so only small corrections were needed. The team moved the secondary mirror by about one-sixteenth of the diameter of a human hair.
Jurling put it in scale: if the mirror's height above the primary mirror were scaled up to the height of the Empire State Building, the change would be a little less than stacking a single U.S. penny on top of the tower.
Matthew Bolcar, Roman's optical systems lead, credited ground testing at Goddard and work by contractors L3Harris and BAE Space and Mission Systems.
Checking out the Wide Field Instrument
The Wide Field Instrument was switched on in September. Since then, NASA says the team has:
- Checked its 18 detectors and their electronics
- Tested the element wheel, which holds filters and other tools
- Turned on the internal calibration LEDs used to measure how the detectors respond to light
- Moved the alignment mechanism from its launch position to its predicted best focus
- Tested the thermal system that keeps components at the right temperatures
NASA says the instrument is central to Roman's goals, including studying dark matter and dark energy.
The coronagraph is next
Roman's second instrument, the Coronagraph Instrument, was initially slightly out of focus, though less than the team expected, and that has been corrected. The team will keep calibrating its camera and deformable mirrors before trying to demonstrate its starlight-blocking abilities in the coming weeks.
