Washington DC - NASA and Boeing are targeting a June 26 return to Earth of the Boeing Starliner from the International Space Station, officials said Tuesday.

Starliner's first crewed mission to the ISS, which had been scheduled to last about eight days, has been extended due to thruster malfunctions and helium leaks.

The spaceship blasted off from Florida atop a United Launch Alliance Altas V rocket on June 5, following years of delays and safety scares – as well as two aborted launch attempts that came as astronauts were strapped in and ready to go.

NASA and Boeing officials said at a press conference that they were looking at a return date of no earlier than June 26 for the two astronauts, Butch Wilmore and Suni Williams, both ex-US Navy test pilots.

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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.

"We want to give our teams a little bit more time to look at the data, do some analysis, and make sure we're really ready to come home," said Steve Stich, manager of NASA's Commercial Crew Program.

Mark Nappi, program manager of Boeing's Commercial Crew Program, said there is "good thruster performance now."

"It's more nominal and the [helium] leaks show that they're stable and less than they've been previously," Nappi said. "That leads us to believe that we have a good safe spacecraft."

The undocking of the Starliner capsule Calypso from the ISS would take place at 10:10 PM ET on June 25, Stich said.

Landing at White Sands Space Harbor in the southwestern US would occur on June 26 at around 4:51 AM ET.

After undocking, Starliner will re-enter the atmosphere, with the crew experiencing 3.5G as they slow down from 17,500 miles per hour to a gentle parachute- and airbag-assisted touchdown.

A successful Starliner mission would help dispel the bitter taste left by the years of safety scares and delays, and provide Boeing a much-needed reprieve from the safety concerns surrounding its passenger jets.