Washington: Indian-origin astronaut Sunita Williams is set to fly into space for the third time on Tuesday as a pilot in the first crewed test flight of Boeing's Starliner spacecraft.

Boeing's Starliner will fly to the International Space Station from Cape Canaveral, Florida.

Starliner will carry Williams, 58, and Butch Wilmore to the International Space Station, in what could be a significant and long-awaited win for the troubled Boeing program.

Scheduled lift-off is scheduled for Monday at 22:34 local time (Tuesday at 8:04 am IST).

"We're all here because we're all ready," the BBC quoted Williams as saying.Our friends and family have heard about it and we've talked about it and they're happy and proud that we're involved in the process of fixing it," he said.

The mission has been delayed for several years due to setbacks in spacecraft development.

If successful, it would become the second private firm capable of providing CRE transportation to and from the ISS, along with Elon Musk's SpaceX.

Such a scenario – in which both SpaceX's Crew Dragon and Starliner are flying regularly – is one the US space agency has been waiting for for a long time.

"Design and development is hard — especially with human spaceflight," Mark Nappi, Boeing vice president and Starliner program manager, said during a news briefing Thursday.,

“There were many surprises along the way that we couldn't overcome. ...It definitely made the team much, much stronger. I'm very proud of how they overcame every obstacle we faced and got us to this point,” Nappi said.

"This is history in the making," NASA Administrator Bill Nelson said of the upcoming Starliner mission during a news conference on March 22. “We are now in the golden age of space exploration.,

SpaceX and Boeing developed their respective vehicles under NASA's Commerce Crew Program, partnering with private industry contractors. From the beginning, the space agency's goal was to operate the two companies together. The Crew Dragon and Starliner spacecraft will serve as backups for each other, giving astronauts the option to continue flying even if technical problems or other failures stop one spacecraft.

Williams received his commission as an Ensign in the United States Navy from the United States Naval Academy in May 1987.

Williams was selected as an astronaut by NASA in 1998 and is a veteran of two space missions, Expeditions 14/15 and 32/33.She served as flight engineer on Expedition 32 and then commander of Expedition 33.

During her first spaceflight, Expedition 14/15, Williams launched with the crew of STS-116 on December 9, 2006, docking with the International Space Station on December 11, 2006.

While onboard, she set a world record for women with four spacewalks totaling 29 hours and 17 minutes. Astronaut Peggy Whitson later broke the record in 2008 with a total of five spacewalks.

On Expedition 32/33, Williams was launched from the Baikonur Cosmodrome in Kazakhstan on July 14, 2012, with Russian Soyuz commander Yuri Malenchenko and Japan Aerospace Exploration Agency flight engineer Akihiko Hoshide.Williams spent four months conducting research and exploration in the orbiting laboratory.

After spending 127 days in space, she landed in Kazakhstan on 18 November 2012.

During their mission, Williams and Hoshide performed three spacewalks to replace a component that relays power from the space station's solar arrays to its systems and to repair an ammonia leak on a station radiator. With 50 hours and 40 minutes, Williams once again set the record for total cumulative space travel by a female astronaut. This record has since been overtaken by Peg Whitson.Williams has spent a total of 322 days in space.

Williams was born in Euclid, Ohio, to Indian-American neuroanatomist Dipa Pandya and Slovenian-American Ursuline Bonnie (Zalokar) Pandya.

He holds a physics degree from the U.S. Naval Academy and a Master of Science degree in engineering management from the Florida Institute of Technology.