Launch of the Water Watcher

Launch of the Water Watcher

The Surface Water and Ocean Topography (SWOT) satellite launched on its way to low-Earth orbit on December 16, 2022, commencing its mission to survey Earth’s surface water. This photo was taken during launch, just after 3:46 a.m. Pacific Time, as the SpaceX rocket carrying the satellite lifted off from Vandenberg Space Force Base in California.

SWOT is an international collaboration, jointly developed by NASA and the Centre National D’Etudes Spatiales (CNES) with contributions from the Canadian Space Agency (CSA) and United Kingdom Space Agency (UKSA).

The SUV-sized satellite will measure the height of water in freshwater bodies and the ocean on more than 90 percent of Earth’s surface. This information will provide insights into how the ocean influences climate change; how a warming world affects lakes, rivers, and reservoirs; and how communities can better manage freshwater and 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 in good health. SWOT will now undergo a series of checks and calibrations before it starts collecting science data in about six months.

“Warming seas, extreme weather, more severe wildfires—these are only some of the consequences humanity is facing due to climate change,” said NASA Administrator Bill Nelson. “The climate crisis requires an all-hands-on-deck approach, and SWOT is the realization of a long-standing international partnership that will ultimately better equip communities so that they can face 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 back about one terabyte of unprocessed 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 radar pulses off the water’s surface and receives the return signal using two antennas on either side of the spacecraft. This arrangement—one signal, two antennas—will enable engineers to precisely determine the height of the water’s surface across two swaths at a time, each of them 30 miles (50 kilometers) wide.

“We’re eager to see SWOT in action,“ said Karen St. Germain, NASA Earth Science Division director. “This satellite embodies how we are improving life on Earth through science and technological innovations. The data that 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.”

Among the many benefits the SWOT mission will provide is a significantly clearer picture of Earth’s freshwater bodies. It will provide data on more than 95 percent of the world’s lakes larger than 62,500 square meters (15 acres) and rivers wider than 100 meters (330 feet) across. Currently, freshwater researchers have reliable measurements for only 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 in observational gaps in areas that don’t have tide gauges or other instruments that measure sea surface height. Over time, that data can help researchers better track sea level rise, which will directly impact communities and coastal ecosystems.

Photograph by NASA/Keegan Barber. Story derived from a NASA news release, adapted for Earth Observatory by Emily Cassidy. Read the full story here.