The observatory
Nancy Grace Roman Space Telescope
Hubble's mirror, a hundred times Hubble's field of view, in the near-infrared. Nobody can ever touch it again, and every design choice follows from that.
2.4 m
Primary mirror
Same diameter as Hubble's, at ≈186 kg against ≈828 kg
0.281 deg²
Field of view
~100× Hubble's WFC3/IR
300.8 MP
Focal plane
18 tiled H4RG detectors
95 K
Detector temperature
Reached passively, no cryocooler
≈4,166 kg
Observatory mass
5-year primary mission
1.50M km
Operating orbit
Halo about Sun–Earth L2
Cutaway
Aperture up, Sun below. Select a numbered component.
Click a numbered component — on the diagram or in the list — to see what it does.
Optical Telescope Assembly
Instruments
Structure & thermal
Spacecraft bus
Schematic, not to scale. Figures from published mission documentation.
Mission
Optical elements
Eight imaging filters spanning 0.48–2.30 µm, a grism (R≈461) and a prism (R≈80–180) on one wheel, plus the two coronagraph bands
| Element | Type | Pivot | Width | Coverage | Notes |
|---|---|---|---|---|---|
| F062 | imaging | 0.620 µm | 0.280 µm | Bluest imaging band; overlaps ground-based R and I. | |
| F087 | imaging | 0.869 µm | 0.217 µm | z-band analogue, used heavily for photometric redshifts. | |
| F106 | imaging | 1.060 µm | 0.265 µm | Y-band; a core High Latitude Wide Area Survey filter. | |
| F129 | imaging | 1.293 µm | 0.323 µm | J-band; a core survey filter. | |
| F146 | imaging | 1.464 µm | 1.030 µm | Very wide band for maximum depth — the microlensing workhorse. | |
| F158 | imaging | 1.577 µm | 0.394 µm | H-band; a core survey filter. | |
| F184 | imaging | 1.842 µm | 0.317 µm | Reaches past the H band for the highest-redshift sources. | |
| F213 | imaging | 2.125 µm | 0.350 µm | Reddest band; probes the most obscured and most distant objects. | |
| G150 | spectroscopy | 1.465 µm | 1.070 µm | Slitless grism, R ~ 461 — emission-line redshifts across the field. | |
| P127 | spectroscopy | 1.050 µm | 1.100 µm | Low-resolution prism for supernova classification. | |
| DARK | dark | — | — | Blocked position for dark-current and reference calibration. | |
| CGI-B1 | imaging | 0.575 µm | 0.058 µm | Coronagraph Band 1 — the primary narrow-FOV imaging demonstration. | |
| CGI-B4 | imaging | 0.825 µm | 0.083 µm | Coronagraph Band 4 — wide-field-of-view mask configuration. |