May 6 (Reuters) -

Boeing's ( BA ) long-awaited first crewed test flight of the

new Starliner space capsule was called off for at least 24 hours

over a technical issue that launch teams could not resolve in

time for the planned Monday night lift-off.

The latest flight was scrubbed with less two hours left

in the countdown as the capsule stood poised for blastoff from

NASA's Kennedy Space Center in Florida atop an Atlas V rocket

furnished by United Launch Alliance, a Boeing-Lockheed Martin

joint venture.

Two years after its initial uncrewed journey to the

International Space Station (ISS), Boeing's ( BA ) new Starliner

astronaut capsule was set for its first crewed test flight on

Monday night, following numerous delays.

Boeing's ( BA ) Crew Space Transportation (CST)-100 Starliner

spacecraft, developed in collaboration with NASA's Commercial

Crew Program, is engineered to carry up to seven passengers, or

a combination of crew and cargo, for journeys to low-Earth

orbit.

Riding aboard the Starliner were NASA astronauts Barry

"Butch" Wilmore, 61, a retired U.S. Navy captain, and Sunita

"Suni" Williams, 58, a former Navy aviator and test pilot.

Here's a quick rundown of key events in the past few years:

Sept. 4, 2015 - Boeing ( BA ) takes the wraps off an assembly plant

for its first line of commercial spacecraft, which NASA plans to

use to fly crews to the ISS.

Nov. 4, 2019 - Boeing ( BA ) says one of three parachutes failed to

open during a crucial unmanned test of the Starliner.

Dec. 20, 2019 - Boeing ( BA ) successfully launches its new

astronaut capsule on an uncrewed debut journey to the ISS.

Dec. 22, 2019 - The spacecraft makes a "bullseye" landing in

the New Mexico desert.

Jan. 7, 2020 - NASA and Boeing ( BA ) investigate software glitches

that stopped the capsule from reaching the ISS.

Feb. 6, 2020 - Boeing ( BA ) narrowly misses a "catastrophic

failure" during its December flight test.

Aug. 25, 2020 - The first Starliner crewed mission is

tentatively slated for 2021.

Oct. 7, 2020 - The chief astronaut for Starliner crewed

flight to the ISS, Chris Ferguson, steps down from the job,

citing family priorities.

July 29, 2021 - A space station mishap prompts NASA to

postpone the launch of the Starliner.

Aug. 3, 2021 - Boeing ( BA ) postpones a Starliner launch after new

glitch.

Aug. 13, 2021 - Boeing ( BA ) returns the spacecraft to the factory

to resolve a valve issue, delaying the launch date.

May 19, 2022 - The Starliner capsule launches on a do-over

uncrewed test flight bound for the International Space Station.

May 20, 2022 - The new Starliner crew capsule docked for the

first time with the International Space Station.

Aug 25, 2022 - Boeing ( BA ) targets early 2023 for the first

Starliner mission carrying astronauts.

June 1, 2023 - Boeing ( BA ) says it is standing down from late

preparations for its first crewed Starliner test flight to

space, which was planned for July 2023, after it discovered two

safety-critical issues with the spacecraft.

(Reporting by Nathan Gomes, Shivansh Tiwary and Nilutpal

Timsina in Bengaluru; Editing by Anil D'Silva and Gerry Doyle)