If you spot a large streak of light in the sky this week, it’s not Santa’s sleigh or a Sidewinder missile going after a balloon. Instead it’s likely the U.S. military’s X-37B space plane taking off for its latest mission.

The uncrewed plane, operated by U.S. Space Force, is set to launch Thursday, Dec. 28 in the evening. The spacecraft has a four-hour window starting at 7 p.m. to take off from NASA’s Kennedy Space Center in Florida. That’s if it is able to make it this time. This launch date is the fourth one announced for the mission. Initially set for Dec. 7 on a SpaceX Falcon Heavy rocket, it was pushed back to Dec. 10. Weather pushed it again to Dec. 11, then a “ground side issue” moved the launch point to Dec. 12 before it was delayed to this new date. 

The December launch dates, even with delays, put the X-37B’s next mission launch roughly around the same time as China’s space plane launch. That went up into orbit earlier this month. China for its part is even more secretive about the project, describing it only as a reusable test spacecraft, but the craft is apparently similar to the American one. 

“It’s no surprise that the Chinese are extremely interested in our space plane, and we’re extremely interested in theirs,” Gen. Chance Saltzman, the top Space Force officer and head of space operations for the military, said at the Space Force Association’s Spacepower Conference earlier this month.

Saltzman went on to call the pair of space planes “two of the most watched objects on orbit while they’re on orbit.”

Subscribe to Task & Purpose Today. Get the latest military news and culture in your inbox daily.

This mission, dubbed “OTV-7,” will test the space plane’s capabilities and also will let the craft serve as a vessel for several scientific experiments. One of those, a NASA project, will test the impact of radiation from “long-duration spaceflight” on plant seeds.

The launch this week is also the first time the X-37B will be sent up into space using a SpaceX Falcon Heavy rocket. Previous missions used the Atlas V rocket mainly, with one using SpaceX’s Falcon 9. 

If this launch isn’t delayed yet again, the X-37B won’t make it back to Earth in the 2024 calendar year. If past missions are any indication, it likely won’t be back in 2025 either. Each mission the space plane has been in has been increasingly longer, with the last one lasting roughly three years. So far, Space Force hasn’t said how long it intends to keep the craft in orbit.

Although Space Force and the U.S. military as a whole are secretive about the X-37B, the launch itself isn’t. Those interested can watch the stream from SpaceX. 

The latest on Task & Purpose