NASA Administrator Jared Isaacman has formally endorsed the revival of Boeing Co.’s (NYSE: BA) Starliner program, arguing that it remains the fastest path to maintaining a second U.S. option for transporting astronauts to low Earth orbit. The agency’s decision comes as SpaceX’s (NASDAQ: SPCX) Starship program is expected to eventually shift focus away from crewed missions.

According to a press release, NASA plans to return Starliner to flight with an uncrewed cargo mission, designated Starliner-1, targeting a launch window between December 2026 and January 2027. The first post-mishap crewed flight, Starliner-2, is currently targeted for 2028. Isaacman noted that Starliner could eventually support up to five crewed missions for the agency.

The decision follows a 2024 Crew Flight Test that was classified as a Type A mishap. During the mission, astronauts Butch Wilmore and Suni Williams were stranded on the International Space Station for 93 days due to propulsion issues and helium leaks, eventually returning to Earth aboard a SpaceX Crew Dragon. NASA’s investigation into the mishap produced 61 recommendations, including the discovery that service-module thrusters operated outside their engineering qualification parameters.

Boeing has reportedly addressed the propulsion issues through thermal modifications and helium leak repairs. However, NASA and Boeing still face certification hurdles, including an additional thruster-valve redesign before astronauts can return to the capsule. The agency also plans to work with Boeing and United Launch Alliance to certify the Vulcan rocket following the retirement of the Atlas V.

The restoration of Starliner is expected to cost NASA an additional $359 million for upgrades and rocket certification. Despite the delays, NASA has continued to rely on SpaceX for near-term crew operations, recently awarding three additional Crew Dragon missions worth $946 million. This brings SpaceX’s total Commercial Crew contract value to $5.92 billion through 2030.

Boeing shares were trading at $184.55 in pre-market trading on Tuesday.