After years of setbacks and delays, Boeing has successfully launched astronauts to the International Space Station (ISS) for NASA. This mission marks the first crewed flight of Boeing’s Starliner capsule, with a pair of NASA pilots onboard to evaluate the spacecraft during a test drive and a weeklong stay at the ISS.

NASA turned to U.S. companies for astronaut transport following the retirement of the space shuttles. Since 2020, Elon Musk’s SpaceX has completed nine taxi trips for NASA, while Boeing has only managed two uncrewed test flights. If this current mission proceeds smoothly, NASA plans to alternate between Boeing and SpaceX for future astronaut transport to and from the space station.

The Capsule

Boeing’s Starliner capsule, white with black and blue trim, stands about 10 feet (3 meters) tall and 15 feet (4.5 meters) in diameter. It can accommodate up to seven people, although NASA’s crews will typically number four. The name “Starliner” was chosen nearly a decade ago, reflecting a nod to Boeing’s earlier Stratoliner and current Dreamliner planes.

Boeing’s previous Starliner test flights were uncrewed. The first, in 2019, faced significant software issues, preventing the capsule from reaching the station. The second attempt in 2022 was successful, but subsequent parachute and flammable tape issues delayed crewed missions. This launch marks the third attempt with astronauts after two earlier countdowns were postponed due to rocket-related issues.

The Crew

Veteran NASA astronauts Butch Wilmore and Suni Williams, both retired Navy captains with previous ISS experience, are leading this test flight. Wilmore, 61, from Mount Juliet, Tennessee, and Williams, 58, from Needham, Massachusetts, stepped in after the original crew withdrew due to delays.

The Test Flight

Starliner launched atop United Launch Alliance’s Atlas V rocket from Cape Canaveral Space Force Station. This event is significant, marking the first time astronauts have flown on an Atlas rocket since NASA’s Project Mercury, which included John Glenn’s historic 1962 orbit of Earth. Wednesday’s launch was the 100th for the Atlas V, a versatile rocket used for both satellites and spacecraft. United Launch Alliance (ULA) is a joint venture between Boeing and Lockheed Martin.

Starliner is expected to reach the ISS, where it will remain docked for over a week, allowing for system checkouts before returning to Earth and landing in the American West.

Starliner vs. Dragon

Both Boeing’s Starliner and SpaceX’s Dragon capsules are designed for autonomy and reusability. This Starliner capsule is the same one used in the initial 2019 test flight. Unlike SpaceX’s Dragon, Starliner features traditional hand controls and switches alongside touchscreens, making it more akin to NASA’s Orion capsules for moon missions. During the mission, Wilmore and Williams plan to briefly take manual control to test the systems.

NASA invested over $4 billion in Boeing for the development of the Starliner capsule, compared to $2.6 billion for SpaceX. SpaceX repurposed its cargo capsule for crew missions, while Boeing has maintained a more traditional approach, including the use of an “astrovan” to transport astronauts to the launch pad, unlike SpaceX’s use of Teslas.

A key difference in landing: Starliner uses cushioning airbags for a ground landing, whereas Dragon capsules splash down at sea.

The Future

Boeing is committed to six Starliner missions for NASA after this one, which will cover transport needs until the station’s planned decommissioning in 2030. Boeing also plans to offer a fifth seat to private clients. SpaceX already sells seats to private individuals and countries for shorter stays at the ISS, separate from NASA’s six-month missions.

Looking ahead, Sierra Space’s mini shuttle, Dream Chaser, aims to deliver cargo to the ISS later this year, with plans to eventually carry passengers. It will launch on ULA’s new Vulcan rocket, the successor to the Atlas V.