NASA Launches New Satellite to Study Earth’s Water

The mission’s data could paint a clearer picture of the effects of climate change

An illustration of the SWOT satellite orbiting Earth
An illustration of the SWOT satellite orbiting Earth NASA / JPL-Caltech

Early Friday morning, the new Surface Water and Ocean Topography (SWOT) satellite launched from the Vandenberg Space Force Base in California, beginning its journey toward a low-Earth orbit.

From its perch, the satellite will measure water on more than 90 percent of Earth’s surface. The data will help scientists better understand the role oceans play in climate change, the effect of global warming on bodies of water and how people can prepare for natural disasters, per a statement. The mission is a collaboration between NASA and ​​the French space agency Centre National d’Études Spatiales.

SWOT “will help us understand where water is, where it’s coming from and where it’s going,” Katherine Calvin, chief scientist and senior climate advisor at NASA, said at a press conference, per The Verge’s Georgina Torbet.

“It’s a game changer,” Rosemary Morrow, an oceanographer at the Laboratory of Space, Geophysical and Oceanographic Studies in France and one of the science leads for the mission, tells Nature News Jeff Tollefson. “It will be like putting on a pair of glasses when you are short-sighted: Things are sort of vague, and then suddenly everything comes into clarity.”

The satellite launched at 6:46 a.m. Eastern time on a SpaceX Falcon 9 rocket and was expected to take about 52 minutes to reach low-Earth orbit. SWOT will spend six months calibrating, then begin collecting data from 554 miles above the Earth, writes’s Josh Dinner.

Most of the data will be collected by an instrument called the Ka-band Radar Interferometer, according to Wired’s Ramin Skibba. It will shoot a pulse of radar off water’s surface, and the spacecraft’s two antennae will receive the reflected return signal. The antennae are on either end of a 33-foot-long boom, per CNN’s Ashley Strickland.

The satellite will allow scientists to collect more detailed measurements of Earth’s water than ever before. It will observe the planet’s entire surface between 78 degrees south and 78 degrees north latitude at least once every 21 days, according to NASA’s statement. As a result, SWOT will be able to observe nearly all of Earth’s lakes larger than 15 acres and rivers wider than 330 feet across.

Scientists currently only have data on 10,000 to 20,000 lakes larger than a hectare. SWOT will look at nearly all 6 million. “We’ve never had measurements like this before,” Tamlin Pavelsky, a hydrologist at the University of North Carolina at Chapel Hill and a SWOT science lead, tells Nature News. “We don’t even have a baseline.”

SWOT will also allow scientists to measure water’s depth. Currently, satellite imagery captures the areas of lakes and rivers, but it’s been difficult to glean how much water is in them. SWOT’s measurements will help scientists “see how the volume of lakes and reservoirs increases and decreases over time,” Pavelsky tells The Verge. “We’ll be able to track the volume of water flowing through rivers from space.”

The new satellite will provide particularly precise data. “This instrument will be able to measure the height of water with centimeter accuracy,” Daniel Esteban-Fernandez, an engineer with NASA’s Jet Propulsion Laboratory (JPL) who helped develop the interferometer, says to Wired. “To think we can improve accuracy by a factor of 100, and from a distance of almost 900 kilometers away from the surface, is kind of incredible.”

SWOT’s data will help scientists study sea-level rise along coastlines and better predict future changes, per CNN. It will also provide insights into flooding and droughts, Benjamin Hamlington, a research scientist at JPL, said in a Tuesday press briefing, per

Hamlington tells Wired that SWOT will also help scientists study factors that influence how much heat and carbon oceans absorb from the atmosphere.

“If SWOT does what we think it’s going to do, it’s going to change the face of hydrology,” Colin Gleason, a geographer at the University of Massachusetts Amherst, says to Nature News.

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