Washington, May 28 (IANS): NASA and Boeing have completed a joint crew flight test checkpoint review ahead of the first flight of Starliner with astronauts to the International Space Station (ISS).

During the checkpoint, mission teams reviewed open work ahead of launch planned no earlier than July 21, including emerging issues that need a path to closure prior to a decision to fuel the spacecraft in June.

"We are taking a methodical approach to the first crewed flight of Starliner incorporating all of the lessons learned from the various in-depth testing campaigns, including Starliner's flight tests and the agency's verification efforts," said Steve Stich, manager of NASA's Commercial Crew Programme.

Teams are now conducting final spacecraft closeouts and preparing for upcoming hardware milestones, including spacecraft fueling, spacecraft rollout to the launch site, and integration with the United Launch Alliance Atlas V rocket.

"Crew safety remains the highest priority for NASA and its industry providers, and emerging issues are not uncommon in human spaceflight especially during development," said Stich.

Starliner spacecraft fuelling is expected to begin as early as mid-June, and there is some operational flexibility in that timeline that can be used if needed.

"Teams will continue to monitor the forward work and determine whether an adjustment in the current launch date is needed," said the US space agency.

NASA has selected Boeing and SpaceX to transport crew to the International Space Station from the US.

These integrated spacecraft, rockets and associated systems will carry up to four astronauts on NASA missions, maintaining a space station crew of seven to maximise time dedicated to scientific research on the orbiting laboratory.