Sensor issue prompts 24-hour delay for classified Falcon 9 mission

The first classified Falcon 9 mission will have to wait at least 24 hours as a sensor issue prevented the NROL-76 mission from launching on its first attempt on April 30, 2017. Photo Credit: Michael Howard / SpaceFlight Insider

CAPE CANAVERAL, Fla. — A hold was called by the launch director some 52 seconds before the expected launch of the classified Falcon 9 mission carrying the NROL-76 payload. Liftoff was planned for 7:15 a.m. EDT (11:15 GMT) April 30, 2017, from Kennedy Space Center’s Launch Complex 39A.

According to SpaceX’s webcast, the hold was called due to an error with a sensor on the first stage. Should the issue get resolved in time, the company has a backup launch window on May 1. It opens at the same time: 7 a.m. EDT (11:00 GMT).

“The team was looking into a sensor issue on the first stage that was a bit out of family with what we were expecting, and out of an abundance of caution, we have decided to scrub today’s launch,” said John Federspiel, SpaceX’s lead mechanical design engineer, who was hosting the company’s webcast.

Aside from the hold at T minus 52 seconds, the countdown otherwise went smoothly. There were indications that fueling occurred early with liquid oxygen beginning to vent from the vehicle at 70 minutes before launch rather than the usual 45 minutes. SpaceX has not revealed why. Normally, rocket grade kerosene and liquid oxygen are loaded at T minus 70 minutes and 45 minutes, respectively.

The NROL-76 mission

As this is a classified mission, the nature of the NROL-76 payload is unknown. When the flight does get underway, launch coverage will continue up until right before the separation of the payload fairing. That should come at about 2 minutes, 48 seconds.

However, SpaceX will continue to broadcast the first stage’s flight after separation all the way back to Landing Zone 1. If successful, it will be the fourth time a SpaceX rocket has landed on a ground-based pad.

Once the Falcon 9 does launch, it will be the 33rd since its maiden flight in 2010 and the fifth in 2017.

Tagged: Falcon 9 Kennedy Space Center Launch Complex 39A Lead Stories National Reconnaissance Office NROL-76 SpaceX

Derek Richardson

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.