Before sunrise Thursday, a rocket carrying the Surface Water and Ocean Topography satellite will take off from Vandenberg Space Force Base north of Santa Barbara. Once the SWOT reaches its target at 553 miles above the Earth’s surface, a new era in the study of climate change will begin. The satellite will be the first to survey nearly all of the Earth’s surface waters, allowing researchers to consistently monitor the volume and movement of every ocean, river, lake and stream on the planet.

This joint mission, led by NASA and the French National Center for Space Research, is supported by a unique alliance of Earth scientists working to answer important questions about floods, climate models and our future water supply. The satellite will be able to see through storm clouds and accurately measure the height of floodwaters when ground sensors are submerged. If a country refuses to share information about water use along a river, spacecraft can provide it instead.

SWOT is designed to observe the planet with unprecedented accuracy and frequency, returning tons of data to help scientists and policymakers plan for floods, droughts and sea level rise.

Scientists say the $1.2 billion mission could change our understanding of water on Earth just as much as the microscope changed our understanding of the human body.

“The possibilities are so endless that I’m almost not sure where to start,” said Tamlin Pavelski, a global hydrologist at the University of North Carolina at Chapel Hill and the mission’s scientific director of hydrology. “It’s like hitting a piñata with a baseball bat and all that candy comes out and you don’t know what to get first.”

Previous satellites observed either the oceans or fresh water. SWOT will be the first to observe both. This mission is the result of a joint effort in oceanography and hydrology, two related scientific disciplines that are often separated.

“The entire water cycle is really important for understanding how climate change is affecting Earth’s surface processes — and not just the transport of water, but also heat,” said Patrick Barnard, Director of Pacific Coast and Marine Science Studies at the US Geological Survey. Headquarters in Santa Cruz, not affiliated with the mission.

The data collected through SWOT will “significantly improve our understanding of not only climate change but also climate variability and how that affects things like droughts and monsoon rains,” he said.

The main instrument of the satellite is the Ka-band radar interferometer, or KarIn. The satellite sends out radio waves, and Karin records how much of that energy returns to the satellite and how long it takes to arrive. Combined with other measurements, these feedback signals tell the satellite whether it senses water and the height of the water surface.

Once fully operational in June, SWOT will scan everything between the Arctic Ocean and Antarctica at least every 21 days. The first mission will run for three years.

“We now have satellites that can tell us where the water is, and we have satellites that can tell us how high the water is, but we don’t have satellites that can do both effectively at the same time. That’s a killer thing Karin can do,” Pavelsky said. “It transforms the world’s water from 2D to 3D.”

For freshwater, SWOT will provide the first comprehensive survey of the planet’s network of rivers, lakes and streams that are too numerous and often too distant to be continuously monitored from the ground. Source