NASA's Nancy Grace Roman Space Telescope is performing better than expected after engineers finished a round of tests and precision adjustments. The Wide Field Instrument now delivers image quality nearly 30% better than predicted, NASA said.
The pre-launch requirement was about 90 nanometers RMS of optical error; after the latest corrections, engineers measured 63 nanometers RMS. The key adjustment moved the secondary mirror by roughly one-sixteenth of the width of a human hair. The team also checked the instrument's 18 detectors, filter wheel, calibration LEDs, alignment mechanism and thermal control system. The Coronagraph Instrument was slightly out of focus and has been brought to its performance targets, with blocking tests planned in the coming weeks.
The sharper optics matter for Roman's dark matter and dark energy surveys. NASA Goddard's Alden Jurling said the survey images "will be even sharper than we expected." Roman launched on August 30.