Watch ULA Try to Finally Launch an NRO Spy Satellite on a Delta IV Heavy Rocket Tonight

A United Launch Alliance Delta IV Heavy rocket carrying a classified payload for the National Reconnaissance Office will take off from Cape Canaveral Space Launch Complex-37 in Florida shortly before midnight on Wednesday. Assuming, that is, there isn’t another one of the last-minute delays that have hounded the mission for months.

The rocket and its semi-mysterious payload, dubbed NROL-44, were originally slated to take off in June. But NROL-44 was delayed until Aug. 29 with no explanation ever offered to the public, according to Ars Technica. It then malfunctioned on that date, with a faulty part causing a hotfire abort after its three RS-68 engines had already begun firing. Repairs took weeks.

NROL-44 was then scheduled to take off on Sept. 26, but skipped that date after problems were discovered with the launch pad’s swing arm retraction system, according to Ars. ULA took several days to resolve the issue. The mission then missed a Sept. 29 launch date of shortly before midnight thanks to inclement weather, which also caused a mobile service tower to roll from its position. Trying to resolve this issue, ULA discovered “a hydraulic leak in the ground system required to move the tower which needs further evaluation.”

The 233-foot Delta IV Heavy is a gargantuan rocket that has only flown 11 times previously, per Space.com, and NROL-44 is only of only five remaining units as ULA plans to replace it with the new Vulcan Centaur. All remaining Delta IV Heavy missions will involve launches for the NRO, as it is currently the only rocket with a vertical payload configuration the military says meets its needs. SpaceX’s Falcon Heavy is significantly cheaper, but uses a horizontal payload configuration.

According to Ars, one source said that the ageing Space Launch Complex-37 (first built in 1959 and modified in 2001) is “headed to the graveyard” with the demise of the Delta IV Heavy.

“I am sure money is being shifted to Vulcan and its launch pad, Space Launch Complex-41,” the source added. “These scrubs will no doubt frustrate other range users.”

Everything is now good to go, with NROL-44 passing numerous pre-flight tests, according to ULA’s live blog on the launch. As of around 7:00 p.m. ET, ULA had verified launch pad ground staff had completed all hands-on work and the “danger area is verified clear,” while weather conditions at Cape Canaveral were clear enough to proceed and expected to remain favorable.

If all goes well for ULA from here on out, tune into the livestream below starting at 11:34 p.m. ET to scope out the launch.