Historic mission: Capsule carrying its first-ever astronauts including Sunita Williams docks with International Space Station

A Boeing Starliner capsule carrying its first-ever astronauts docked with the International Space Station on May 7 after overcoming unexpected challenges arising from thruster malfunctions and helium leaks. (Photo/Agencies)

The spacecraft, named "Calypso," successfully docked with the space station at 1:34 pm ET (1734 GMT), as the two vessels flew over the southern Indian Ocean, allowing crewmates Butch Wilmore and Sunita Williams to enter a while later. (Photo/Agencies)

Docking was delayed by more than an hour after some of Starliner's thrusters that provide fine maneuvering initially failed to kick in, forcing the astronauts to perform a "hot fire" to activate them. (Photo/Agencies)

Wilmore and Williams are the first crew to fly Starliner, which Boeing and Nasa are hoping to certify for regular rides to the ISS -- a role SpaceX has been fulfilling for the past four years. (Photo/Agencies)

The spaceship blasted off from Florida atop a United Launch Alliance Altas V rocket on June 6 following years of delays and safety scares -- as well as two recently aborted launch attempts that came as astronauts were already strapped in and ready to go. (Photo/Agencies)

Before launch, it was known that there was one helium leak affecting Starliner. While non-combustible, the helium provides pressure to the propulsion system. But it was determined the leak was too small to cause much of an impact. (Photo/Agencies)

Starliner is just the sixth type of US-built spaceship to fly Nasa astronauts, following the Mercury, Gemini and Apollo programs in the 1960s and 1970s, the Space Shuttle from 1981 to 2011, and SpaceX's Crew Dragon from 2020. The United States was left reliant on Russian Soyuz rockets to go to the ISS between 2011 and 2020. (Photo/Agencies)

During their roughly weeklong stay on the orbital outpost, Butch Wilmore and Suni Williams will continue to evaluate the spacecraft systems, including simulating whether the ship can be used as a safe haven in the event of an emergency on the ISS. (Photo/Agencies)