Washington: NASA's Boeing Starliner spacecraft piloted by Indian-origin Sunita 'Suni' Williams and fellow NASA astronaut Barry 'Butch' Williams lifted off to space on its historic maiden voyage toward the International Space Station.

Sunita is the first female astronaut to fly on the first flight of a crewed spacecraft. The launch that marks Sunita's third foray into space is the sixth inaugural journey of a crewed spacecraft in US history.

The United Launch Alliance Atlas V rocket carrying the Boeing Starliner's 'Calypso' capsule lifted off from the Kennedy Space Centre at Cape Canaveral in Florida, NASA said today.

The aerospace giant's mission was hit by multiple delays previously. Williams and Wilmore are now expected to spend more than 24 hours traveling to the International Space Station, and dock with it at 12:15 p.m. ET on Thursday.

A previous attempt to launch the mission dubbed the Crew Flight Test was cancelled on Saturday, less than four minutes left of the countdown as the ground launch computer went into an automatic hold.

The problem was later traced to a faulty power supply source connected to the computer, with the malfunctioning unit since replaced.

The launch is part of NASA's "commercial crew programme", which selected Boeing and SpaceX to develop spacecraft to carry astronauts to the International Space Station after NASA retired its Space Shuttle Program in the year 2011.

Boeing received over USD 4 billion in US federal funds to develop the Starliner, while SpaceX received about USD 2.6 billion.

While the Elon Musk-owned SpaceX company's Crew Dragon has performed 12 crewed missions to the ISS since its first launch on May 30, 2020,

Boeing's Starliner has been faced with multiple setbacks. Meanwhile the Starliner capsule will dock with the ISS and the astronauts will be at the ISS conducting a range of tests for about a week. Starliner will then undock from the ISS re-enter Earth's atmosphere and make a parachute and airbag-assisted landing in the southwestern United States on June 10, NASA said.

Sunita has traveled to space twice before, once on a NASA space shuttle in 2006 and then on a Russian Soyuz capsule in 2012 in an earlier. She's logged 322 total days in space.

NASA selected Boeing and SpaceX in September 2014 to transport crew to the International Space Station from the United States. These integrated spacecraft, rockets and associated systems will carry up to four astronauts on NASA missions, maintaining a space station crew of seven to maximize time dedicated to scientific research on the orbiting laboratory.

Sunita and Barry Wilmore were both former commanders of the International Space Station.

Sunita, from Needham, Massachusetts, earned a physical science degree from the US Naval Academy, and a master's in engineering management from the Florida Institute of Technology.

Her first spaceflight was Expedition 14/15 (from December 2006 to June 2007) launching on space shuttle Discovery's STS-116 mission to reach the International Station, according to NASA.

While onboard, Sunita established a world record for women at the time with four spacewalks. She concluded her tour of duty by returning to Earth with shuttle Atlantis' STS-117 flight to land at Edwards Air Force Base in California on June 22, 2007.

Selected as an astronaut by NASA in June 1998, Sunita has spent a total of 322 days in space on two missions and accumulated 50 hours and 40 minutes of cumulative EVA time on seven spacewalks.

She worked with ROSCOSMOS on its contribution to the space station and with the first Expedition crew.

Meanwhile, 61-year-old, Barry Wilmore has logged 178 days in space and has 25 hours and 36 minutes of time on four spacewalks.

Boeing has planned six manned missions for the platform over the next six years, the projected end of the ISS' operating lifespan.

(With Inputs From Agencies)