Roman

A 2.4 m telescope with the Wide Field Instrument: eighteen 4k × 4k H4RGHgCdTe detectorMercury-cadmium-telluride infrared arrays (Teledyne H2RG and H4RG) used by JWST, Euclid and Roman. Each pixel is read non-destructively, so an exposure is sampled many times up the ramp.-10 detectors imaging 0.281 deg²square degreeUnit of solid angle: one degree by one degree on the sky. The whole sky is about 41,253 deg²; the full Moon covers about 0.2 deg². at 0.11″ per pixel from 0.48 to 2.3 µm, with slitless spectroscopyslitless spectroscopyPlacing a dispersing element (often a grism, a prism–grating combination) in the beam with no slit, so every source in the field gets a spectrum at once. Efficient for surveys; spectra of neighbours can overlap.. Hubble-class resolution over about 200 times the field of WFC3/IR. Core surveys measure weak lensingweak gravitational lensingCoherent distortion of distant galaxy shapes, at the percent level, by mass along the line of sight. Averaged over millions of galaxies it maps dark matter and the growth of structure; it needs exquisite PSF control., BAObaryon acoustic oscillationsA preferred separation of about 150 Mpc (comoving) in the galaxy distribution, imprinted by sound waves in the early Universe. Measuring it at many redshifts traces the expansion history like a standard ruler. and type Ia supernovae and monitor the Galactic bulgeGalactic planeThe plane of the Milky Way's disc, a band around the sky at Galactic latitude b ≈ 0°. Dense in stars, gas and dust: rich for stellar work, crowded and heavily extincted for extragalactic surveys, which usually avoid it. for microlensingmicrolensingBrightening of a background star as a foreground star passes almost in front of it and bends its light. A planet around the lens adds a short anomaly, revealing planets at several AU independent of their brightness. planets; a coronagraph demonstrates high-contrast imaging.

Operator

NASA

Orbit

Sun–Earth L2

Aperture

2.4 m mirror

Passband

0.48 µm – 2.3 µm

Launch

30 August 2026