Continuing the trend of late night rocket launches this week, the United Launch Alliance is scheduled to launch one of its Delta IV rockets from Cape Canaveral, Florida at 12:47AM ET this evening. The vehicle will send a pair of surveillance satellites into a super high orbit for the United States Air Force. Once in orbit, the satellites will act as the Air Force’s eyes in space — looking out for objects that could pose a threat to the US’s other military satellites.

The two satellites are part of the Geosynchronous Space Situational Awareness Program, or GSSP. It’s the Air Force’s initiative to keep an eye on objects in geosynchronous orbit (GEO) — an orbital path located about 22,000 miles above Earth. A satellite in GEO matches the Earth’s rotation; so if you’re looking from the ground, it will seem like the satellite is staying in the same place in the sky. That makes GEO a good place to put surveillance satellites that continually monitor a specific area of Earth.

Looking out for objects that could pose a threat to the US’s military satellites

Because of this benefit, the Department of Defense maintains a lot of important military satellites in GEO, like those that provide early warnings of missile launches on Earth. These satellites are critical to the US’s intelligence, so the DOD wants to keep them safe. But as other nations’ space capabilities continue to grow, the US is worried that its GEO satellites could face an attack by other satellites nearby.

That’s where these new GSSP satellites come in. The satellite pair will join two previously launched GSSP satellites in near-geosynchronous orbit, and from there, the satellites will track the movements of other human-made objects in GEO. "GSSAP will present a significant improvement in space object surveillance, not only for better collision avoidance, but also for detecting threats," General William Shelton, the former commander of the Air Force, said in a speech announcing the program in 2014. "GSSAP will bolster our ability to discern when adversaries attempt to avoid detection and to discover capabilities they may have, which might be harmful to our critical assets at these higher altitudes."

The GSSP’s theme of "eyes in the sky" is echoed in ULA’s artwork for tonight’s launch. The image shows the Delta IV rocket in front of giant owl, with its eyes glowing bright yellow. And in case you don’t get the artwork’s message, the tagline for the launch is the Latin phrase "Videmus Omnia," which translates to, "We see all."

So far, weather is looking good for a launch tonight. There’s an 80 percent chance that conditions will be favorable, according to Patrick Air Force Base. ULA's live coverage of the event will begin 20 minutes prior to launch at 12:27AM ET.