September 17, 2021

SpaceX crew capsule relocated outside space station before Boeing mission


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SpaceX’s Crew Dragon spacecraft moves in for docking at the zenith port on the space station’s Harmony module Wednesday. Credit: NASA TV/Spaceflight Now

Four astronauts rode a SpaceX Crew Dragon capsule for a flight from one International Space Station docking port to another Wednesday, clearing the way for arrival of a Boeing Starliner crew ferry ship on an unpiloted test flight later this month.

The relocation maneuver, performed with the spacecraft on autopilot, moved the Crew Dragon Endeavour spacecraft from the forward port of the space station’s Harmony module to Harmony’s an upward-facing docking adapter.

Dragon commander Shane Kimbrough, pilot Megan McArthur, and mission specialists Akihiko Hoshide and Thomas Pesquet put on their SpaceX pressure suits and took their seats inside the Crew Dragon Endeavour spacecraft before an automated undocking from the forward port at 6:45 a.m. EDT (1045 GMT).

All four crew members flew inside the Dragon spacecraft for the relocation operation Wednesday, just in case a major problem prevented the capsule from linking up with the space station again. Kimbrough’s crew launched aboard the Crew Dragon Endeavour spacecraft April 23 from Florida. They are scheduled to return to Earth in November.

During their mission lasting more than six months, Kimbrough’s crew would use the Dragon capsule as a lifeboat to escape the space station in an emergency. NASA did not want the astronauts on the space station without an escape pod if the Crew Dragon failed to redock with the complex.

The relocation maneuver Wednesday appeared to go without a hitch.

The Crew Dragon spacecraft backed away more than 200 feet (60 meters) from the space station’s forward port, then pulsed its Draco thrusters to reposition itself above the complex to line up with a similar docking port on the zenith, or space-facing, side of the Harmony module.

Teams commanded the spacecraft to begin its approach to the zenith port, and Crew Dragon autonomously moved in for docking using navigation cues from on-board sensors.

The spacecraft linked up with the zenith port at 7:35 a.m. EDT (1135 GMT), and mission control confirmed 12 hooks closed to create a firm connection with the space station.

Kimbrough and his crewmates, now 89 days into their mission, planned to take off their white SpaceX pressure suits and enter the space station again after equalizing pressure on both sides of the docking port.

The relocation maneuver was the second time a Crew Dragon spacecraft has swapped docking ports at the space station, following a similar operation in April to clear the way for arrival of a Dragon cargo capsule.

This time, NASA wanted to move the Crew Dragon to the zenith port to make room for docking of Boeing’s Starliner spacecraft later this month.

The Boeing capsule is set for launch July 30 from Cape Canaveral on its second unpiloted orbital test flight, a redo of a demo mission in 2019 plagued by software problems. Assuming an on-time launch, the Starliner spacecraft is scheduled to dock with the space station July 31.

The software for the first test flights of the Starliner spacecraft is certified for docking with the forward port on the Harmony module, according to NASA. SpaceX’s Crew Dragon spacecraft was also initially certified to dock only with Harmony’s forward location.

“The forward port offers a less complex approach and presents better lighting conditions without the Earth in view of navigation and tracking sensors,” said Gary Jordan, a NASA spokesperson at the Johnson Space Center in Houston. “Utilizing that forward port on these initial test flights puts the safety of the crew and the two vehicles first.”

Once the Starliner spacecraft is cleared for regular crew rotation flights, the Boeing capsule will be capable of docking with either port on the space station.

“Starliner will be able to dock to both ports and have the ability to perform port relocation maneuvers by the Starliner 1 mission,” Jordan said. “This is similar to the approach taken during the first dockings of Crew Dragon during its first test flights to the station.”

Boeing’s CST-100 Starliner spacecraft is designed to carry astronauts to and from the space station. If the upcoming test flight goes well, NASA will clear the next Starliner demonstration mission to launch with a three-person crew.

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Follow Stephen Clark on Twitter: @StephenClark1.


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