For the fourth time this week, a rocket launch from Cape Canaveral was stopped with seconds remaining in the countdown Friday night, when a SpaceX Falcon 9 rocket automatically aborted its liftoff with a new GPS navigation satellite during the engine startup sequence.
The Falcon 9 rocket was just two seconds from launching the U.S. Space Force’s next GPS satellite at 9:43 p.m. EDT Friday (0143 GMT Saturday) when an automated abort halted the countdown.
“Five, four, three,” a member of SpaceX’s launch team called out on the countdown audio net. “And we have an abort. All agencies stand by.”
John Insprucker, a veteran SpaceX engineer providing commentary on the company’s launch webcast, confirmed the team scrubbed the launch attempt Friday night because there was not enough time in the 15-minute window to identify and resolve the problem.
“We got down to about T-minus 2 seconds approximately,” Insprucker said on SpaceX’s launch webcast. “We were just starting the engine ignition sequence when we had a hold. We then began safing (the rocket). We did not get into lighting all nine of the Merlin rocket engines.”
While it did not appear the engines fired, a flash of green light from the base of the rocket suggested the engines’ TEA-TEB ignitor source briefly activated before computers stopped the countdown at Cape Canaveral’s Complex 40 launch pad.
“Right now the vehicle is being safed,” Insprucker said before signing off on the webcast. “There don’t appear to be any issues on the launch pad, but that does end our launch opportunity for tonight.”
While engineers started probing the cause of the hold Friday night, the launch team kicked off steps to drain the Falcon 9 rocket of its kerosene and liquid oxygen propellants.
SpaceX had a backup launch opportunity reserved Saturday night at 9:39 p.m. EDT (0139 GMT Sunday) on the military-run Eastern Range at Cape Canaveral. But SpaceX did not confirm if teams would prepare for another launch attempt Saturday, or if the problem might cause a longer delay.
Elon Musk, SpaceX’s founder and CEO, tweeted that the Falcon 9 launch was aborted after an “unexpected pressure rise in the turbomachinery gas generator,” referring to equipment used on the rocket’s Merlin main engines.
In any event, forecasters at Cape Canaveral were predicting stormy weather Saturday night. In an outlook issued earlier Friday, they expected an 80 percent chance of unfavorable weather for a launch attempt Saturday night.
A Lockheed Martin-built GPS navigation satellite was ready for liftoff on top of the Falcon 9 rocket Friday night. It is the fourth in a new generation of GPS satellites with longer lifetimes, higher power, and more accurate navigation signals.
The GPS 3 SV04 spacecraft is set to join 31 operational GPS satellites in orbit 12,550 miles (20,200 kilometers) above Earth.
Friday’s launch attempt was the first for the Falcon 9 rocket carrying the GPS 3 SV04 satellite, but the abort echoed similar last-minute holds encountered by other launchers earlier in the week.
SpaceX fueled a different Falcon 9 rocket two times this week on nearby pad 39A at the Kennedy Space Center, aiming to send the launcher into space with 60 more satellites for the company’s Starlink internet work.
But SpaceX scrubbed a launch attempt Monday morning just 31 seconds prior to liftoff due to poor weather. The Falcon 9 rocket was again fueled for launch Thursday morning on pad 39A, but SpaceX called off the mission with 18 seconds left in the countdown after detecting unexpected data from a ground sensor.
The same Starlink launch was initially planned for launch Sept. 17. But SpaceX delayed the mission to wait for improved sea conditions in the Falcon 9’s offshore recovery zone, where a drone ship is positioned in the Atlantic Ocean for landing of the the rocket’s first stage booster.
SpaceX aims to try again to launch the Falcon 9 rocket with the 60 Starlink satellites Monday at 7:51 a.m. EDT (1151 GMT).
Musk tweeted early Saturday that SpaceX is beginning a “broad review of launch site, propulsion, structures, avionics, range & regulatory constraints this weekend” in a bid to improve launch availability.
“I will also be at the Cape next week to review hardware in person,” Musk tweeted.
A Delta 4-Heavy rocket from United Launch Alliance, a rival of SpaceX in the U.S. launch services market, was also supposed to blast off from Cape Canaveral on Wednesday night. Its launch was also aborted in the final minute, when the computer-run countdown sequencer stopped the clock seven seconds before liftoff, a moment before the Delta 4-Heavy’s three main engines were programmed to ignite.
ULA has not announced a new launch date for the Delta 4-Heavy rocket, which is set to loft a classified payload for the National Reconnaissance, owner of the U.S. government’s fleet of intelligence-gathering spy satellites.
The Delta 4-Heavy rocket had also run into a series delays before the countdown abort Wednesday night. ULA announced Aug. 26 as the original launch date for the Delta 4-Heavy rocket and its NRO spy cargo, but the mission has been grounded repeatedly, primarily by problems with the Delta 4 launch pad at Cape Canaveral.
A countdown Aug. 29 stopped at T-minus 3 seconds, after one of the Delta 4-Heavy’s three main engines had ignited. ULA traced that problem to a pressure regulator on the launch pad.
Engineers refurbished the launch pad’s pressure regulators before setting a new target launch date Sept. 26. But the flight was again delayed to assess a potential issue with the launch pad’s swing arms designed to retract from the Delta 4-Heavy rocket at liftoff.
ULA teams contended with stormy weather during a pair of launch attempts Monday and Tuesday. After storms cleared from the spaceport Tuesday afternoon, technicians discovered a hydraulic leak on the ground system that rolls the launch pad’s mobile gantry into position for liftoff, forcing another canceled launch attempt before Wednesday night’s countdown ended in the final seconds.
Amid the string of scrubs at Cape Canaveral, another U.S. launcher was set to fire into orbit from Wallops Island, Virginia, with a cargo ship bound for the International Space Station.
Northrop Grumman scrubbed the Antares rocket’s launch attempt Thursday in Virginia less than three minutes before takeoff. Officials later attributed the scrub to an issue with ground software, and a second countdown Friday culminated in a successful launch to begin a mission to deliver nearly 8,000 pounds of supplies and experiments to the space station.
The Antares rocket blasted off at 9:16 p.m. EDT (0116 GMT), just 27 minutes before the Falcon 9’s abort Friday night.
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