PRETTY

The mission

The Passive REflecTomeTry and dosimetrY (PRETTY) is a 3U CubeSat mission which was launched successfully in October 2023. It is the first CubeSat to exploit GNSS-R grazing altimetry technique at L5 frequency and using beam steering to measure sea state, ice and ocean currents at high precision. It also provides a characterization of the radiation dose environment.

Platform: 3U CubeSat with 3-axis pointing.
Payloads: Software-defined GNSS-Reflectometry receiver & L-band multi-patch antenna (BGA, TU Graz), Radiation dosimeter (Seibersdorf Labs).
Programme: General Support Technology Programme (GSTP).
Consortia: Beyond Gravity Austria, TU Graz, Seibersdorf Labs.

Mission description

PRETTY (Passive REflecTometry and dosimeTrY) is a 3U CubeSat, launched in October 2023, demonstrating for the first time Global Navigation Satellite Systems (GNSS) reflectometry (GNSS-R) at low grazing angles using the E5/L5 frequency, transmitted by the European Galileo and American GPS constellations. 
The passive reflectometry payload is adopting a novel approach that receives direct and reflected signals from the same GPS satellite at low grazing angles geometry (incident angle 75-85 degrees) and correlates them for producing relative altimetry data. The measurement technique, called “grazing altimetry”, was demonstrated for the first time in space by PRETTY using the L5/E5 frequency in order to measure ice surfaces over polar areas, sea ice and Eddie currents over the ocean area to an accuracy of 100 cm (goal of 50 cm). Measuring eddies and their energy at sub-mesoscale level (down to 10 km scales), will significantly improve our understanding of the total ocean energy transport and its role in natural and anthropogenic climate change.  

PRETTY's second payload, SATDOS, is a compact reference dosimeter tailored for CubeSat applications. The platform is outfitted with dose integration enabling the evaluation of mission total ionizing dose (TID), as well as in-orbit single event effects (SEE), which will in fine support the reliability and sustainability of future missions on similar orbits. 

The main mission objectives are: 

• Demonstrate the passive reflectometry payload focusing on grazing altimetry, applying cross-correlation of direct and reflected signals.
• Measure and map the relative height of ice surfaces and sea ice in the polar regions.
• Measure the relative height of the sea surface and map the eddy currents.
• To assess the total radiation dose and the dose at different geographic regions of interest, providing a technology demonstration of a reference dosimeter system.

Mission status

Launch: 08/10/2023 to SSO 568 km on Vega VV-23.
Status: Operations successfully ended on Oct. 2024, after planned 1 year of nominal operations, Post Flight Review (PFR) in Nov. 2024.