It’s a NRO-go for an Atlas V launch on Wednesday night [Updated]

Atlas V on SLC-41 after being scrubbed due to an unexpected system response from remotely commanded ground-system liquid-oxygen valves.

An Atlas V 531 rocket with the NROL-101 payload on the launch pad is seen Monday before returning to the Vertical Integration Facility for additional payload environmental control system repairs/checkouts.

Super-telephoto view of the upper ECS (environmental control system) duct after repair on November 4, 2020.

Close-up of the NROL-101 fairing artwork. The Elvish script translates to “Goodness Persists.”

This is the first flight of Atlas V with the GEM-63 solid rocket booster. ULA aims to build flight experience before the GEM-63XL fly on Vulcan as early as next year.

Update 6:15pm EST: A ground-systems issue got United Launch Alliance again. Prior to the opening of the Atlas V launch window on Wednesday evening, an issue related to ground-system liquid-oxygen valves could not be solved in time for a launch attempt from Florida.

The company will now stand down for 48 hours to address the issue, which would allow for SpaceX to attempt a launch of a GPS III satellite for the Space Force on Thursday.

Original post 11:25am EST: United Launch Alliance returns to one of its two main pads at Cape Canaveral Air Force Station Wednesday to try to break a string of recent launch scrubs due to various issues, mostly related to ground systems.

The company’s Atlas V rocket is scheduled to liftoff from Space Launch Complex-41 at 5:54pm EST (22:54 UTC), carrying a satellite for the National Reconnaissance Office. The mission is named NROL-101, and its final orbit is classified. There is a 70-percent chance of favorable conditions.

The venerable Atlas V rocket, which has flown 85 missions since its debut in 2002, will be testing new hardware with this flight. For the first time, the Atlas V will use solid-rocket boosters built by Northrop Grumman rather than Aerojet Rocketdyne. These GEM-63 boosters cost less than the booster previously used. United Launch Alliance plans to use an extended version of this booster, the GEM-63L, on its Vulcan rocket, which could make its first flight in a year or so.

Perhaps the biggest question heading into today’s launch attempt is whether the Atlas V rocket will get off the ground. This mission was originally scheduled to launch on Tuesday, but after a rollout on Monday, the company discovered a problem with an environmental control system duct. This may have been damaged during high winds at the launch site on Monday. After being rolled back into its hangar, where the duct was swapped out, the Atlas V rocket rolled back to the pad on Tuesday.

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So far, so good—as of Wednesday morning the company says everything is on track for an Atlas V liftoff later in the day.

United Launch Alliance could do with a successful liftoff. It has been a difficult couple of months as the company has struggled to launch another mission for the National Reconnaissance Office, an important customer that pays a premium to get its high-dollar satellites into space.

This NROL-44 mission, due to launch on a Delta IV Heavy rocket on a nearby pad, has scrubbed half a dozen times since late August. Most of these scrubs were due to issues with ground support equipment and often occurred within seconds of the planned liftoff time. This has raised questions about aging infrastructure at the Delta launch site in Florida. A new launch date has not yet been set for the mission, which the US government had hoped to loft into space in June.

The company’s webcast for today’s launch should begin about 20 minutes before liftoff.