Science

PRETTY

European CubeSat (GNSS Reflectometry — Ice & Ocean Height) · ESA / Beyond Gravity / TU Graz

PRETTY (Passive REflecTometry and dosimeTrY), a shoebox-sized ESA CubeSat that measures ice sheet and ocean height using a genuinely clever trick: it compares a GPS or Galileo signal arriving directly from a satellite with the same signal bouncing off Earth's surface first, then measures the tiny timing difference between the two to calculate surface height to within half a meter. It launched October 9, 2023 on the same Vega rocket as THEOS-2 and FORMOSAT-7R, and is the first CubeSat ever to attempt this measurement technique at a shallow grazing angle rather than looking straight down — a viewing geometry ESA's own engineers compared to looking at a sea through Venetian blinds instead of from directly above.