Last Space Shuttle landing anniversary highlights US crew launch gap

NASA’s last Space Shuttle landing came 15 years ago this week, when Atlantis returned to Kennedy Space Center on July 21, 2011, and closed the agency’s shuttle program with STS-135. The anniversary is more than nostalgia for aerospace operators: the replacement strategy was supposed to give NASA redundant commercial crew access to the International Space Station, but Boeing’s Starliner problems have left SpaceX as the only working US crew provider named in the current setup.

Atlantis had launched on July 8, 2011, from Kennedy Space Center and landed 13 days later at the Shuttle Landing Facility. STS-135 was not originally meant to be a standard final flight. It began as STS-335, the backup rescue mission for Endeavour’s STS-134 flight.

What was the last Space Shuttle landing?

The final Space Shuttle landing was Atlantis’s return from orbit on July 21, 2011, at Kennedy Space Center in Florida. That touchdown ended NASA’s shuttle operations and shifted US human spaceflight toward Russian Soyuz seats and, later, commercial crew vehicles from SpaceX and Boeing.

The rescue-flight planning came out of the post-Columbia safety regime. NASA assigned separate STS-3xx numbers to Launch On Need missions, which could send another shuttle to retrieve astronauts if an orbiter could not safely re-enter. Examples included STS-317 as the contingency flight for STS-116 and STS-318 for STS-117. The Hubble servicing mission STS-125 was an exception, with STS-400 designated as its backup.

STS-135 was different because there was no shuttle left to stand by for a rescue. With the program closing, NASA’s fallback plan was for the crew to leave the ISS on Soyuz capsules if Atlantis could not safely come home. The flight also carried only four astronauts, a crew size the shuttle had not used since Challenger’s STS-6 mission in 1983.

Who flew on STS-135?

Christopher Ferguson commanded STS-135. He later joined Boeing’s Commercial Crew Program and was assigned to Starliner, though he did not fly on that capsule. Douglas Hurley served as pilot and later flew SpaceX’s first crewed Crew Dragon test flight in 2020. Sandra Magnus and Rex Walheim flew as mission specialists.

After Atlantis retired, the US relied on Russia to move astronauts to and from the ISS. NASA then awarded Commercial Crew contracts to SpaceX and Boeing to bring crew launches back to US soil. SpaceX reached that milestone in 2020 with Crew Dragon. Boeing’s crewed Starliner effort followed in 2024, but the mission ran into failures and faults that led managers to return the capsule empty from the ISS. The Starliner test crew is scheduled to return in 2025 on a SpaceX vehicle, according to the account of the mission status.

NASA and Boeing have not set a firm date for another crewed Starliner trip to the ISS. That leaves the agency short of the two-provider redundancy it sought after retiring the shuttle.

What happens after Crew Dragon?

SpaceX’s Crew Dragon is reusable, and SpaceX has said each vehicle should be able to support 15 flights with refurbishment. No additional Crew Dragons are planned for production, according to the current plan described for the fleet. That may be enough to cover the remaining ISS program and some period after it, but a longer-term replacement would still be needed. For SpaceX, the likely successor is Starship.

The orbiters themselves remain part of the story. Atlantis is displayed at Kennedy Space Center in a pose meant to suggest flight, while the California Science Center has mounted Endeavour with an external tank and solid rocket boosters in a launch-stack configuration. Discovery’s location is contested: some lawmakers want it moved from the Smithsonian’s Steven F. Udvar-Hazy Center in Virginia to Houston, while others have pointed to a used Orion capsule as an alternative exhibit for Texas.

This story draws on original reporting from The Register.