Second Time’s the Charm for Crew-6

Liftoff of four crew members to the International Space Station went off without a hitch at 12:34 am ET this morning. It was the second try, following a scrub on Monday caused by a technical problem with ground equipment. This time the launch went perfectly and Crew-6 is in orbit and on the way to a docking about 24 hours from now.

Although the launch itself was fine, SpaceX had to switch to backup motors to open hooks that allow the nose cone to open after Crew Dragon was in orbit. The nose cone must be open in order for the spacecraft to dock at ISS at 1:17 am ET tomorrow morning.

During a post-launch press conference, SpaceX Senior Director for Human Spaceflight Benji Reed said they think it was a bad sensor. Crew Dragon has 12 hooks, 6 of which open or close the nose cone. All 12 are needed for docking. Each of the 12 hooks has three sensors or “limit switches” that provide data on the status of the hook. One of the sensors on one of the hooks indicated it was not opening so the system automatically shifted to a backup set of motors for all of them and it worked fine. “We believe we’ll be able to ignore the data from that one of 36” sensors with no elevated risk for docking or for closing the nose cone six months from now when the crew comes home.

The launch of Crew-6 is part of the regular crew exchanges for the ISS, which has been permanently occupied by international crews rotating on roughly 4-6 month schedules for more than 22 years.

In this case, the crew is two NASA astronauts, Steve Bowen and Woody Hoburg, Russian cosmonaut Andrey Fedyeav, and United Arab Emirates astronaut Sultan AlNeyadi.

Their launch on Monday was scrubbed two minutes and 14 seconds before launch when a clogged filter in ground equipment disrupted the flow of triethylaluminum-triethylborane or TEA-TEB needed to ignite the Falcon 9 rocket’s kerosene/liquid oxygen Merlin engines. TEA-TEB sparks with oxidizer to allow the engines to fire.

SpaceX’s Crew Dragon spacecraft are reusable and this is the fourth flight of this one, Endeavour. The first stages of their Falcon-9 rockets also are reusable, returning to land either on a drone ship at sea or back on land at Cape Canaveral Space Force Station adjacent to Kennedy Space Center.  Some Falcon 9 first stages have launched as many as 15 times, but this one just completed its first trip, landing on the drone ship Just Read the Instructions.

Crew-6 is replacing Crew-5. Those four crew members, NASA’s Nicole Mann and Josh Cassada, Roscosmos’s Anna Kikina, and JAXA’s Koichi Wakata, will come home after an approximately 5-day handover period once Crew-6 docks.

Crew Dragon was developed as a Public-Private Partnership between NASA and SpaceX, where they shared the costs of development. SpaceX retains ownership of the system and NASA purchases services with the goal of being just one of many customers.

Crew-6 is the seventh launch of a Crew Dragon to the ISS for NASA (the first was called Demo-2). SpaceX also has launched two Crew Dragon private astronaut flights already — Inspiration4 spent three days in Earth orbit, and Axiom-1 docked to the ISS for about two weeks — and a third, Axiom-2, will launch in a few months.

 

This article has been updated.