Update for 8:30 am ET: A SpaceX Falcon 9 rocket has successfully launched NASA's Surface Water and Ocean Topography satellite into orbit to study Earth's oceans and water like never before. See launch and rocket landing video, and read our full launch wrap story.
SpaceX will launch a powerful NASA water-monitoring satellite early Friday morning (Dec. 16), and you can watch the action live.
The Surface Water and Ocean Topography (SWOT) satellite is scheduled to lift off atop a SpaceX Falcon 9 rocket from California's Vandenberg Space Force Base on Friday at 6:46 a.m. EST (1146 GMT; 3:46 a.m. local California time).
You can watch the launch live here at Space.com, courtesy of NASA, or directly via the agency. Coverage is expected to begin at 6 a.m. EST (1100 GMT).
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The Falcon 9 that will launch SWOT is a veteran; its first stage has flown five previous orbital missions, SpaceX wrote in a mission description. If all goes according to plan, the booster will come back to Earth for a sixth time on Friday, landing at Vandenberg about 7.5 minutes after liftoff.
The Falcon 9's upper stage will continue carrying SWOT to orbit, eventually deploying the satellite 52.5 minutes after launch.
SWOT is a joint effort of NASA and the French space agency CNES, with contributions from the Canadian and United Kingdom space agencies. The mission will study Earth's water levels in unprecedented detail, helping scientists get a better handle on climate change and its effects.
"Once in orbit, SWOT will measure the height of water in freshwater bodies and the ocean on more than 90% of Earth's surface," NASA officials said in a statement.
"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 prepare for disasters, such as floods," they added.
SWOT's liftoff is part of a busy week for SpaceX. On Sunday (Dec. 11), a Falcon 9 lofted Hakuto-R, a moon lander built by Tokyo-based company ispace that's also carrying a small rover for the United Arab Emirates.
And Elon Musk's company is targeting another mission on Friday as well: A Falcon 9 is expected to launch two satellites for Luxembourgish-French telecom company SES from Florida's Cape Canaveral Space Force Station at 4:21 p.m. EST (2121 GMT).
SWOT was originally supposed to launch on Thursday morning (Dec. 15), but SpaceX took an extra day to investigate moisture detected in two of the Falcon 9's nine first-stage Merlin engines.
Editor's note: This story was updated at 10 p.m. ET on Dec. 15 to state that SpaceX is targeting just one other launch on Friday apart from SWOT. The company had been aiming to launch a batch of its Starlink satellites that day as well but ended up pushing that mission to Saturday (Dec. 17).
Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.