SpaceX scrubbed the launch from Florida of a four-man crew heading to the International Space Station early Monday with less than three minutes remaining in the countdown, delaying the start of a six-month mission to examine a problem with a ground system needed to ignite the Falcon 9 rocket’s main engines.
SpaceX’s launch director ordered the hold in the countdown less than two-and-a-half minutes before the scheduled launch time of 1:45 a.m. EST (0545 GMT).
“This is the LD on countdown. Hold Hold Hold. We are standing down due to a TEA-TEB ground issue,” the launch director said.
TEA-TEB stands for triethylaluminum-triethylborane, the fluid used to ignite the Falcon 9 rocket’s Merlin main engines. The TEA-TEB fluid is pyrophoric, meaning it ignites on contact with air, often appearing as a green flash just before ignition of the Merlin engines.
The four-man crew was on-board the Dragon Endeavour spacecraft on top of the Falcon 9 rocket when SpaceX called off the launch attempt.
Commander Stephen Bowen, a veteran of three space shuttle missions, was flanked by three spaceflight rookies in the Dragon cockpit: NASA pilot Warren “Woody” Hoburg, astronaut Sultan Alneyadi, and Russian cosmonaut Andrey Fedyaev. The crew is set to begin a half-year expedition on the International Space Station, replacing a four-person crew scheduled to return to Earth on a different SpaceX spacecraft early next month.
SpaceX drained kerosene and liquid oxygen from the Falcon 9 rocket within about one hour of the scrub, allowing the astronauts to disarm the Dragon spacecraft’s launch escape engines. Ground teams returned to Launch Complex 39A and helped the crew members out of their seats before they returned to crew quarters a few miles away at NASA’s Kennedy Space Center.
NASA said engineers were investigating an issue preventing them from confirming a full load of the TEA-TEB ignition source.
“I’m proud of the NASA and SpaceX teams’ focus and dedication to keeping Crew-6 safe,” said NASA Administrator Bill Nelson. “Human spaceflight is an inherently risky endeavor and, as always, we will fly when we are ready.”
NASA and SpaceX officials decided to forego a launch opportunity early Tuesday due to a forecast of bad weather, and the position of the space station in its orbit would prevent the Dragon spacecraft from getting to the complex within one day if the mission lifted off Thursday.
Managers set the next launch attempt for Thursday, March 2, at 12:34 a.m. EST (0534 GMT). The Dragon Endeavour spacecraft will dock with space station’s Harmony module early Friday.
The Crew-6 mission will be SpaceX’s sixth operational crew rotation flight to the space station, and SpaceX’s ninth human spaceflight mission overall, including the Demo-2 test flight in 2020 with NASA astronauts Doug Hurley and Bob Behnken, and two fully commercial astronaut missions.
The Dragon Endeavour spacecraft set to fly on the Crew-6 mission will be going to space for the fourth time, more than any other SpaceX crew capsule to date. The same vehicle was used on the Demo-2 test flight with Hurley and Behnken in 2020.
The Falcon 9 booster assigned to the Crew-6 launch, numbered B1078, is making its first flight.
The arrival of the Crew-6 mission at the space station will temporarily raise the size of the lab’s crew to 11. Bowen’s crew will replace the Crew-5 mission, which has been at the station since October.
The Crew-5 mission — commanded by NASA astronaut Nicole Mann, with pilot Josh Cassada, Japanese astronaut Koichi Wakata, and Russian cosmonaut Anna Kikina — will return to Earth on their SpaceX-owned Dragon spacecraft in early March, weather permitting. The Dragon spacecraft will target a splashdown off the coast of Florida.
When the mission takes off, the Falcon 9 and Dragon spacecraft will head northeast from Florida’s Space Coast to line up with the space station’s orbital track. Flying parallel to the U.S. East Coast, the Falcon 9 will shed its first stage about two-and-a-half minutes into the mission, allowing the booster to descend back to a landing on a drone ship in the Atlantic Ocean.
The rocket’s single-engine upper stage will fire more than six minutes to place the Dragon spacecraft and four crew members in a preliminary orbit. The Dragon will separate from the rocket a few minutes later, open its nose cone to reveal its docking mechanism, then execute a series of Draco thruster burns to fine-tune its path to the space station.
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