On Friday, December 16, 2022, a SpaceX Falcon 9 rocket launched with the Surface Water and Ocean Topography (SWOT) spacecraft on board from Space Launch Complex 4E at Vandenberg Space Force Base in California. Developed jointly by NASA and the National Center for Space Studies (CNES), with contributions from the Canadian Space Agency (CSA) and the UK Space Agency, SWOT is the first satellite mission to observe almost all water on the surface of the Earth, measuring the height. of water in the lakes, rivers, reservoirs and ocean of the planet. Credit: NASA/Keegan Barber
The Surface Water and Ocean Topography (SWOT) mission, led by NASA and the French space agency CNES, will provide high-definition data on salt and fresh water on Earth’s surface.
A satellite built to observe nearly all of our planet’s surface water lifted off on its way to low Earth orbit at 3:46 am PST on Friday, December 16. The Surface Water and Ocean Topography (SWOT) spacecraft was launched on a SpaceX rocket. from Space Launch Complex 4E at Vandenberg Space Force Base in California. SWOT was built for NASA and the French space agency Center National d’Études Spatiales (CNES) and also has contributions from the Canadian Space Agency (CSA) and the United Kingdom Space Agency.
With a main mission of three years, the SWOT satellite will measure water height in freshwater and ocean bodies over 90% of the Earth’s surface. This data will provide new insights into how the ocean influences climate change; how global warming affects lakes, rivers and reservoirs; and how communities can better prepare for disasters such as floods.
After SWOT separated from the second stage of a SpaceX Falcon 9 rocket, ground controllers successfully acquired the satellite’s signal. Initial telemetry reports showed the spacecraft to be in good health. The SWOT will now undergo a series of checks and calibrations before it begins collecting scientific data in about six months.
“Warming seas, extreme weather, more severe wildfires — these are just some of the consequences humanity faces as a result of climate change,” said NASA Administrator Bill Nelson. “The climate crisis requires a comprehensive approach, and SWOT is the realization of a long-term international partnership that will ultimately better equip communities to meet these challenges.”
SWOT will cover the entire Earth’s surface between 78 degrees south and 78 degrees north latitude at least once every 21 days, sending approximately one terabyte of raw data per day. The scientific heart of the spacecraft is an innovative instrument called the Ka-band Radar Interferometer (KaRIn), which marks a major technological advance. KaRIn bounces the radar pulses off the surface of the water and receives the return signal via two antennas on either side of the spacecraft. This arrangement (one signal, two antennas) will allow engineers to accurately determine the height of the water’s surface in two strips at once, each 30 miles (50 kilometers) wide.
This illustration depicts the Surface Water and Ocean Topography Satellite, a mission led by NASA and the French space agency Center National d’Études Spatiales (CNES). The scientific heart of the SWOT satellite is the Ka-band Radar Interferometer (KaRIn) instrument, which will measure the height of water in Earth’s lakes, rivers, reservoirs and ocean. To do this, KaRIn will transmit radar pulses to the Earth’s surface and use two antennas, seen to the left and right of the spacecraft bus, to triangulate the bouncing back signals. Mounted at the ends of a 10-meter-long boom, the antennas will collect data on two strips of the Earth’s surface at the same time, each 50 kilometers wide and located on either side of the satellite. KaRIn will operate in two modes: a lower resolution mode over the ocean will involve significant onboard processing of the data to reduce the volume of information sent during downlinks to Earth; a higher resolution mode will be used primarily on land. Credit: NASA/JPL-Caltech
“We look forward to seeing SWOT in action,” said Karen St. Germain, director of NASA’s Earth Sciences Division. “This satellite embodies how we are improving life on Earth through science and technological innovations. The data this innovation will provide is essential to better understanding how Earth’s air, water and ecosystems interact , and how people can thrive on our changing planet.”
A significantly clearer picture of Earth’s freshwater bodies is among the many benefits the SWOT mission will deliver. It will provide data on more than 95% of the world’s lakes larger than 15 acres (62,500 square meters) and rivers larger than 330 feet (100 meters) in diameter. Currently, freshwater researchers only have reliable measurements for a few thousand lakes around the world. SWOT will push that number into the millions.
Along the coast, SWOT will provide information on sea level, filling observational gaps in areas that lack tide gauges or other instruments that measure sea surface height. Over time, this data can help researchers better track sea level rise, which will directly affect coastal communities and ecosystems.
This illustration depicts the SWOT (Surface Water and Ocean Topography) satellite, a mission led by NASA and the French space agency Center National d’Études Spatiales (CNES). The scientific heart of the SWOT satellite is the Ka-band Radar Interferometer (KaRIn) instrument, which will measure the height of water in Earth’s lakes, rivers, reservoirs and ocean. Credit: NASA/JPL-Caltech
Such an ambitious mission is made possible by NASA’s long-standing commitment to working with agencies around the world to study Earth and its climate. NASA and CNES have built a decades-long relationship that began in the 1980s to monitor Earth’s oceans. This collaboration pioneered the use of a space-based instrument called an altimeter to study sea level with the launch of the TOPEX/Poseidon satellite in 1992.
“This mission marks the continuation of 30 years of collaboration between NASA and CNES in altimetry,” said Caroline Laurent, director of orbital systems and applications at CNES. “It shows how international collaboration can be achieved through an innovative mission that will help us better understand climate change and its effects around the world.”
SWOT measures will also help researchers, policy makers and resource managers better assess and plan for things, including floods and droughts. By providing information about where water is, where it comes from, and where it’s going, researchers can improve river flood projections and monitor the effects of drought on lakes and reservoirs.
“SWOT will provide vital information given the pressing challenges posed by climate change and sea level rise,” said Laurie Leshin, director of NASA’s Jet Propulsion Laboratory. JPL developed the KaRIn instrument and manages the US portion of the mission. “This SWOT will fill the gaps in our knowledge and inform future actions is the direct result of commitment, innovation and collaboration going back many years. We are excited to put SWOT science into action.”
More information about the mission
The Jet Propulsion Laboratory (JPL), which is managed for NASA by the California Institute of Technology (Caltech) in Pasadena, California, is leading the US component of the project. For the flight system payload, NASA provided the KaRIn instrument, a GPS science receiver, a laser retroreflector, a dual-beam microwave radiometer, and NASA instrument operations. CNES provided the Doppler Orbitography and Radioposition Integrated by Satellite (DORIS) system, the dual-frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio frequency subsystem (together with Thales Alenia Space and with the support of the UK Space Agency), the satellite platform and the ground control segment. CSA provided the KaRIn high power transmitter assembly. NASA provided the launch vehicle, and the agency’s Launch Services Program, based at Kennedy Space Center, managed the associated launch services.