Leaky liquid hydrogen line causes scrub of WorldView-4 launch – UPDATE
A small liquid hydrogen (LH2) leak triggered a scrub of today’s scheduled launch of a United Launch Alliance (ULA) Atlas V 401. The rocket was slated to loft the WorldView-4 Earth-imaging satellite into orbit from Space Launch Complex 3E at Vandenberg Air Force Base in California.
Approximately 30 minutes before the scheduled 11:30 a.m. PDT (2:30 p.m. EDT; 18:30 GMT) liftoff, Tory Bruno, ULA President and CEO, tweeted the launch had been scrubbed. It was the first day-of-launch scrub of an Atlas V for technical reasons in four years – over 30 flights.
“Very small ground side LH2 leak,” Bruno tweeted. “Forming an ice ball on the umbilical. Outside our history. Standing down attempt today to resolve.”
Noting the ice accretion was a condition not encountered before, Bruno said there was some concern the buildup could possibly interfere with umbilical separation.
“Always better to be on the ground, wishing you were in the air than the other way around,” Bruno stated in a follow-up tweet.
Had the launch occurred as scheduled, it would have marked ULA’s 66th flight of an Atlas V rocket, and the 33rd in the base “401” – 4-meter payload fairing, zero strap-on solid rocket motors, and a single RL10-powered Centaur stage – configuration.
The 401 is by far the most common variant of the Atlas V family and can loft nearly 21,605 pounds (9.8 metric tons) to low-Earth orbit.
Joining the WorldView-4 satellite on this mission are seven CubeSats. The tiny satellites are to be launched on behalf of the National Reconnaissance Office as part of a rideshare program dubbed ENTERPRISE.
The company plans to re-try the launch after a 24-hour reset, tentatively scheduled for 11:30 a.m. PDT (2:30 p.m. EDT; 18:30 GMT) Saturday, September 17, 2016, pending successful resolution of the leaky LH2 line. Weather is expected to have a 90 percent chance of favorable conditions at liftoff. ULA will stream the mission live on the Internet, with coverage beginning at 11:05 a.m. PDT (2:05 p.m. EDT; 18:05 GMT).
UPDATE: United Launch Alliance has announced that the launch of WorldView-4 will slip to NET than Sunday, Sept. 18, 2016. The Colorado-based firm issued the following statement in the early evening of Friday, Sept. 16:
“Vandenberg Air Force Base, Calif. (Sept. 16, 2016) – The launch of a United Launch Alliance Atlas V carrying the WorldView-4 satellite is scheduled for Sunday, Sept. 18, to allow the team additional time to evaluate the cause of the ground leak anomaly experienced during propellant tanking. The launch window opens at 11:30 a.m. PDT.”
UPDATE 2: In a release the morning of Sunday, September 18, United Launch Alliance has announced a further delay in the launch of the WorldView-4 mission:
“Vandenberg Air Force Base, Calif. (Sept. 18, 2016, 6:15 a.m. PDT) — The launch of a United Launch Alliance Atlas V carrying the WorldView-4 mission was scrubbed today due to a fire at Vandenberg Air Force Base. The launch vehicle and payload are secure in the Mobile Service Tower at SLC-3. The launch is rescheduled for no earlier than Tuesday, Sept. 20.”
Curt Godwin has been a fan of space exploration for as long as he can remember, keeping his eyes to the skies from an early age. Initially majoring in Nuclear Engineering, Curt later decided that computers would be a more interesting - and safer - career field. He's worked in education technology for more than 20 years, and has been published in industry and peer journals, and is a respected authority on wireless network engineering. Throughout this period of his life, he maintained his love for all things space and has written about his experiences at a variety of NASA events, both on his personal blog and as a freelance media representative.