Joint mission of CNES and NASA
The SWOT mission is a joint CNES and NASA mission in collaboration with the Canadian (CSA) and UK (UKSA) space agencies. It is dedicated to measuring the surface water level of lakes and rivers, the flow of rivers and to the very fine and precise determination of the dynamics of the sea. This is the first space mission that will study almost all the water on Earth’s surface. This altimetry scientific adventure began 30 years ago, in 1992, with the launch of the TOPEX/Poseidon satellite and continued with the Jason satellites, including NOAA (National Oceanic and Atmospheric Administration) and EUMETSAT.
Major technological breakthrough
SWOT is based on a major technological breakthrough: wide-swath interferometry with the KaRIn instrument, designed by the Jet Propulsion Laboratory (JPL), to which CNES and Thales Alenia Space contribute by producing the radio frequency part of the instrument. KaRIN has two Ka-band SAR antennas with a distance of 10 meters. They offer a two-dimensional observation 120 km wide, with a horizontal resolution of the order of 50-100 m. SWOT will also carry the NADIR module, which consists of the same instruments as the Jason 1, 2 and 3 satellites, including the Poseidon the dual frequency altimeter manufactured by Thales Alenia Space. The Nadir module includes the DORIS system, manufactured by Thales, for precision orbitography, as well as an AMR (Advanced Microwave Radiometer) microwave radiometer, GPSP localization payload (GPS Payload) and a set of laser reflectors LRA (Laser Retro-reflector Array) ) made by JPL.
Able to closely observe coastlines
Specifically, the SWOT satellite from 2023 will expand the current capabilities of oceanographic altimetry to coastal currents and hydrology. In this field, thanks to measurements of continental water surface elevations, SWOT will be able to assess river flows and freshwater stocks on a planetary scale and monitor changes. In oceanography, with a resolution 10 times greater than existing technologies, the mission will observe, with a resolution of 10 to 20 kilometers, the fine structures of ocean circulation and their interactions with the deep ocean. In turn, this will provide a better understanding of the effects on marine life, ecosystems, water quality and energy transfers. Finally, SWOT with radar interferometry will be able to closely observe coastlines to study their interactions with ecosystems, water quality and shoreline erosion, etc.
Enable more sustainable management of freshwater stocks
In general, by measuring more precisely the level of the seas, the flow and levels of rivers and lakes, but also by studying the coasts, SWOT will allow a more sustainable management of freshwater resources on Earth. The satellite data will help to better understand the rise in sea level and the development of coastlines in a changing climate. In this regard, the mission will provide essential information to many scientific communities at an international level.