Watch live: ULA to launch spy satellite after 24-hour delay

Dec. 8 (UPI) — United Launch Alliance is preparing once more to launch its Delta 4-Heavy rocket.

The company’s most powerful rocket was scheduled to carry a spy satellite into space on Friday, but a communications error forced ULA to delay the liftoff until Saturday evening.

During preflight checks, engineers discovered a “redundant communication link between the control center and the launch site,” according to a statement released by ULA.

Saturday’s launch from Vandenberg Air Force Base in California is scheduled for 11:06 p.m. EST, 8:19 p.m. PST.

“Weather has improved! We are at 70% chance of favorable launch weather for tonight’s #NROL71 launch,” ULA announced on Twitter.

ULA will stream a live broadcast of Saturday’s launch.

The payload for Saturday evening’s flight belongs to the National Reconnaissance Office, one of the U.S. government’s five major intelligence agencies. The mission will be ULA’s 132nd — the 71st for NRO.

NRO and ULA have offered very little information about the satellite being carried into space Saturday.

According to new site SpaceFlight 101: “NROL-71 is most likely a heavy Keyhole KH-11 image reconnaissance satellite.”

The telescope-like spy satellites are capable of capturing high-resolution images useful to U.S. military and intelligence agencies.

“We are proud to launch this critical payload in support of our nation’s national security mission,” Gary Wentz, vice president of government and commercial programs at ULA, said in a news release. “As the nation’s premiere launch provider, the teams have worked diligently to ensure continued mission success, delivering our customer’s payloads to the precise orbits requested.”

The Delta 4-Heavy is one of the most powerful U.S. rockets currently in operation. It can carry up to 14,000 pounds into geosynchronous orbit, 28,000 pounds into geo-transfer orbit and 53,000 pounds into low Earth orbit. The rocket’s power is derived from a trio of boosters, each featuring liquid hydrogen-liquid oxygen engines. Together, the three engines produce 2.1 million pounds of thrust.