| Telescope Parameter | NASA Nancy Grace Roman (WFI) | Hubble Space Telescope (WFC3) | James Webb Space Telescope (NIRCam) |
|---|---|---|---|
| Field of View (FOV) | 0.281 deg² (100x Hubble) | ~0.0028 deg² | ~0.0026 deg² |
| Primary Mirror Diameter | 2.4 meters (identical to Hubble) | 2.4 meters | 6.5 meters (segmented beryllium) |
| Angular Resolution | ~0.11 arcseconds/pixel | ~0.13 arcseconds/pixel | ~0.031 to 0.063 arcsec/pixel |
| Primary Science Mission | Galactic microlensing, rogue exoplanets, dark energy survey | Deep individual galaxy/stellar targets, UV-optical astronomy | Deep high-z cosmos, pencil-beam exoplanet atmospheric spectroscopy |
| Exoplanet Detection Method | Gravitational Microlensing (wide statistical census) | Direct imaging of young massive giants, transits | Transit transmission & emission spectroscopy |
As addressed in astrophysics community debates, Roman is not an inferior competitor to JWST. JWST is a colossal pencil-beam observatory designed to scrutinize single planetary atmospheres or ultra-faint first galaxies. Roman is a wide-field survey engine that captures 100 times the sky area of Hubble in a single shot with equal sharpness, finding thousands of rare targets for JWST to follow up.
Normal exoplanet hunting relies on radial velocity wobbles or transit shadow dips, requiring a bright host star. Free-floating "rogue" planets drift isolated through interstellar space without a star. General Relativity dictates that their mass acts as a gravitational lens, bending and temporarily magnifying light from background stars for 1 to 3 days when passing in front.
Roman's Wide Field Instrument incorporates eighteen 4096×4096 pixel HgCdTe infrared focal plane arrays (300 megapixels total). In 5 years of operation, Roman will survey over 20,000 square degrees, charting over 100,000 gravitational microlensing light curves in the dense stellar fields toward the Galactic Center.