You know that good feeling of accomplishment you get when you finish a project after working on it for a couple days?
The feeling gets stronger when a project that’s taken two weeks or two months is wrapped up.
Now imagine seeing something to fruition after TWO DECADES!
Yep, oh what a feeling that would be.
That’s what Tamlin Pavelsky, Ph.D., a professor of global hydrology at UNC Chapel Hill, experienced when he watched a Falcon 9 rocket launch from Vandenberg Space Force Base in California in December 2022.
The rocket’s payload was the Surface Water and Ocean Topography (SWOT) satellite. The satellite and its mission are the product of a collaboration between NASA and scientists around the world. Pavelsky is the U.S. representative and the hydrology science lead.
SWOT is designed to provide an unprecedented global picture of the world’s river flows, lake water storage and ocean circulation.
“Water is perhaps the single most important resource for humans and nature, but it also drives the most destructive natural disasters,” said Pavelsky during a talk at Morehead Planetarium and Science Center in Chapel Hill. “Yet even though it is so important, there is a lot we don’t know about where our water is and how it is changing.”
SWOT will utilize radar in a unique way. It will measure the height of water’s surface in lakes, rivers and oceans across the globe while also using radar to detect where water is.
The $1.1 billion satellite will send radar waves about one centimeter long toward Earth, where they will bounce off the surface water and back to two antennas on the ends of a 35-foot boom attached to the satellite.
That will effectively create two triangles on either side of the satellite, each covering 30 miles. By measuring how long it takes the pulse to return to the satellite, scientists can measure the distance the radar beam traveled and figure out where the surface is.
Scientists can then combine the height of the water’s surface with data about the underwater topography and figure out how much water is in each body of water.
Yep, that’s quite the calculation!
Pavelsky also hopes SWOT will provide a better understanding of flood events, which should result in the creation of a more accurate flood-warning system.
The satellite will measure the water level, inundation extent and slope of rivers and flood plains. The data will help researchers create a 3D model of a river system and show how a flood moves through the area.
SWOT will also turn its radar on more than two million lakes, measuring how big and deep the lakes are. That information will help scientists understand how the water volume in the lake is changing. That’s especially important when those lakes serve as reservoirs, providing water supplies to cities and towns.
Scientists can also use data about ocean height to better understand ocean currents.
Pavelsky calls ocean currents a massive air conditioner for the globe. Not only does water absorb heat, oceans conduct air currents around the globe. This cooling effect is becoming more important as the world warms due to climate change.
“The currents take the extra energy created by global warming and mix it into the ocean depths,” said Pavelsky. “SWOT will give us a better insight into ocean circulation, how currents work and how the increased warmth is impacting the ocean. That will be used to study the ocean’s role in climate change.”
The SWOT satellite project will orbit Earth between the 78th parallels north and south. That’s roughly between the Arctic Ocean and Antarctica. It will take observations of each location on Earth every 10 days.
NASA expects the SWOT mission to last at least 3 1/2 years. Pavelsky is hoping for longer.
