This afternoon, the United Launch Alliance (ULA) is set to launch its most powerful rocket — the Delta IV Heavy — sending up a secret spy satellite for the National Reconnaissance Office (NRO). The mission will be the 132nd mission for the ULA, and the latest of many launches the company has done for the NRO, a significant customer of the launch provider.

This particular launch has struggled to actually get into space. Originally set for December 7th, the flight was delayed multiple times throughout the end of last year. Then, in early January, ULA decided to take a break from launch attempts in order to review some technical issues with the rocket that stopped it from launching on December 19th. Now at long last, the company is ready to try to light this rocket again.

As is the case with all NRO launches, it’s unclear what’s actually going into space; the NRO keeps the purposes of its missions under wraps. However, the satellite is likely pretty heavy and is perhaps going to a high orbit if it requires the power of the Delta IV Heavy. The rocket consists of three cores strapped together, which provide more than 2 million pounds of thrust at liftoff. Altogether the Delta IV Heavy is capable of putting more than 62,500 pounds into low Earth orbit.

While we don’t know the exact reason for the mission, the flight does have a signature NRO patch that features a terrifyingly large animal. This patch sports a giant eagle ripping through cloth, wearing dog tags with the initials of an old Union commander during the Civil War, Col. Joshua L. Chamberlain. It matches many of the NRO’s previous patches, which have showcased giant octopuses, snakes, and scary medieval iconography.

Today’s mission, dubbed NROL-71, is slated for takeoff at 2:05PM ET / 11:05AM PT out of Vandenberg Air Force Base in California. ULA plans to live stream the launch, with coverage beginning about 20 minutes before takeoff. If you’re light on plans this Saturday afternoon, check back to see this rocket launch live.

Update January 19th, 9:00AM ET: This story was updated to include the new launch time and clarify the many delays of the mission. The original launch on December 7th was delayed due to a communication issue, and then again due to weather and other technical concerns.