NASA will conduct a crucial fueling test of its Artemis 1 moon rocket today (Sept. 21), and you can watch it live.
Technicians are scheduled to begin loading supercold liquid hydrogen and liquid oxygen propellants into Artemis 1's Space Launch System (SLS) megarocket today at 7:15 a.m. EDT (1115 GMT). Watch it live here at Space.com, courtesy of NASA, or directly via the space agency.
Artemis 1 will use the SLS to launch an Orion capsule on an uncrewed journey to lunar orbit and back from NASA's Kennedy Space Center in Florida. The test flight was supposed to lift off late last month but was delayed twice by glitches, the second of which was a liquid hydrogen leak that occurred during the leadup to a planned liftoff on Sept. 3.
The Artemis 1 team replaced two seals at the site of the leak, a "quick disconnect" linking the SLS core stage with a fuel line from its mobile launch tower. Today's test will help determine if that fix worked. If all goes well, the mission will remain on track to launch on Sept. 27, with a backup opportunity on Oct. 2.
It's unclear how long today's test will last; in an update on Friday (Sept. 16), NASA officials wrote that it "will conclude when the objectives for the test have been met."
The fueling test isn't the only spaceflight action on tap for today. A Russian Soyuz rocket is scheduled to launch cosmonauts Sergey Prokopyev and Dmitry Petelin and NASA astronaut Frank Rubio toward the International Space Station from Baikonur Cosmodrome in Kazakhstan at 9:54 a.m. EDT (1354 GMT). You can watch that here at Space.com as well when the time comes.
Artemis 1 is the first mission in NASA's Artemis program, which aims to establish a long-term human presence on and around the moon by the end of the 2020s. If all goes well with Artemis 1, Artemis 2 will launch astronauts on a trip around the moon in 2024 and Artemis 3 will land people near the lunar south pole a year or two later.
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 on Facebook.