Spaceflight Insider

Various issues prompt 24-hour scrub of Atlas V with SBIRS GEO-3

Atlas V attempt 1

Sitting on Space Launch Complex 41, the Atlas V 401 waits for launch. However, various issues ultimately caused the flight to be scrubbed for the day. Photo Credit: Michael Howard

CAPE CANAVERAL, Fla. — It wasn’t meant to be. That’s what mission teams working to get a United Launch Alliance (ULA) Atlas V 401 rocket with its missile-detection satellite off the ground must have been thinking. An instrumentation issue plus a fouled range caused a 24-hour scrub to be called late in the Jan. 19 launch window.

The 40-minute window opened at 7:46 p.m. EST on Jan. 19 (00:46 GMT on Jan. 20). However, less than 15 minutes before the first launch opportunity, an issue with two sensors in the RD-180 engine at the base of the Atlas V necessitated delaying the liftoff. Ultimately, a new T-minus 0 was set for 8:16 p.m. EST (01:16 GMT).

In the meantime, engineers in Denver, ULA’s headquarters, developed a backup plan to work around the loss of the two sensors.

At about 10 minutes before the new liftoff time, the launch director performed the customary “go, no-go” flight readiness poll. All of the launch teams report they were “go” with one exception: Atlas Propulsion was still verifying the workaround.

This resulted in the liftoff time being postponed again to 8:26 p.m. EST (01:26 GMT) – the very end of the window.

Atlas Propulsion finished their verification and the team was set to launch. The countdown exited its hold at T-minus 4 minutes. Unfortunately, just a few seconds later at T-minus 3 minutes, 23 seconds, the range called “hold, hold, hold.” An aircraft had entered into restricted airspace.

With less than 4 minutes remaining in the window, there was no time to recycle the countdown to try again. As such, the launch director officially called a scrub for the day at 8:36 p.m. EST (01:36 GMT).

The ULA launch team will try again tomorrow during another 40-minute window. It opens 4 minutes earlier at 7:42 p.m. EST on Jan. 20 (00:42 GMT on Jan. 21). A backup date of Saturday was also requested.

Per the 45th Space Wing, the weather tomorrow is expected to have a 30 percent chance of violating launch constraints. The primary concerns are cumulus and thick clouds.

Video courtesy of United Launch Alliance



Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity. You can find him on twitter @TheSpaceWriter.

Reader Comments

Did anyone ever confirm that it was a DHS/CBP aircraft that violated the range?

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