Shortly before liftoff, SpaceX cancels a crew launch due to ignition issues

Enlarge / SpaceX's Crew-6 mission is seen this weekend before leaving planet Earth. Nasa

Just over two minutes before SpaceX's Falcon 9 rocket was scheduled to launch a crew of four astronauts to the International Space Station early Monday, the mission was canceled due to a ignition fluid.< /p>

NASA's Crew-6 mission was scheduled to lift off at 1:45 a.m. ET from Launch Complex 39-A in Florida at Kennedy Space Center. During the space agency's webcast, the host first mentioned the problem with the TEA-TEB ignition fluid about five minutes before the scheduled liftoff time. Mission operators were unable to resolve the technical issue before the instant launch window opened.

The crew was safe aboard the Crew Dragon spacecraft. NASA astronauts Stephen Bowen, the mission commander, and Warren "Woody" Hoburg, its pilot, along with United Arab Emirates astronaut Sultan Alneyadi and Roscosmos cosmonaut Andrey Fedyaev, both mission specialists, will exit the vehicle later Monday morning after the thruster shuts down. loaded from the rocket.

The mission has a reinforcement opportunity early on Tuesday, February 28. But while the weather was ideal on Monday morning, it may be less so on Tuesday. Conditions at the launch site are expected to be good, but forecasters are concerned about the weather along the rocket's path, which would come into play in the event of an abort during the launch causing Crew Dragon to perform a return trip. emergency on Earth. NASA and SpaceX also have the option to launch the Crew Dragon mission on March 2, 3, and 4. (Update: NASA and SpaceX are targeting Thursday, May 2 at 00:34 ET or 05:34 UTC.)

Shortly after the cleanup, SpaceX tweeted a little more information about the cause: "Abandoned Crew-6 launch tonight due to TEA-TEB ground system issue," said society.

TEA-TEB is a combination of triethylaluminum (TEA) and triethylborane (TEB). They are essentially two different metallic elements each bonded to three hydrocarbon atoms. These molecules are held together by fairly tenuous bonds that break easily. In contact with oxygen, TEA-TEB therefore ignites spontaneously.

This is useful for igniting rocket engines, which is a rather tricky thing to do, at least when it comes to starting the engines precisely at a certain time, in a carefully controlled way. For the Merlin 1D engines inside the Falcon 9, oxygen is pumped into the engine combustion chambers to meet TEA-TEB. After combustion begins, kerosene is injected into the chamber and fuel flow to the TEA-TEB igniter is shut off. Then, to increase thrust, the flow of oxygen and kerosene is increased.

Early in development of the Falcon 1 and Falcon 9 rockets, SpaceX struggled to safely handle TEA-TEB and fire the Merlin engines when it wanted to. “The best thing about TEA-TEB is that it ignites on contact with air,” said SpaceX original launch director Tim Buzza. "The worst thing about TEA-TEB is that it ignites on contact with air."

Given the danger of working with the chemical, SpaceX likely made the right decision to cancel Monday morning's launch.