WATCH: Boeing’s Starliner Spacecraft moved into place ahead of key test flight to ISS

Boeing’s Starliner Spacecraft and a United Launch Alliance Atlas V rocket were rolled onto a launch pad Monday ahead of a key test flight.

It’ll be the Starliner’s second un-crewed flight test to the International Space Station, intended to show the Starliner is capable of ferrying astronauts to the space station as part of NASA”s Commercial Crew Program.

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“The Boeing flight test is extremely important,” NASA Administrator Bill Nelson said. “We do not put crews on a spacecraft and fly until we’ve tested.”

The Starliner was unable to lift off for a test last week due to a problem at the Space Station.

A Russian spacecraft malfunctioned, firing its thrusters while docked at the ISS, temporarily knocking the space station out of its normal orientation.

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With that problem resolved, NASA, Boeing, and ULA are targeting Tuesday at 1:20 p.m. for their next attempt.

The mission will test the end-to-end capabilities of the Starliner, from launch to docking, re-entry, and a desert landing in the Western United States.

“That’s going to be of critical importance,” NASA Associate Administrator  Bob Cabana said. “That we demonstrate we can do rendezvous proximity operations, that all the sensors work, the guidance navigation, that everything works.”

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SpaceX has been flying crewed operation missions to the Space Station since late last year.  If all goes well for Boeing, it could be flying a crewed flight test before the end of this year.

“Competition is good, not only because it brings about the most efficient, productive, and cost effective work product,” Nelson said. “What it does is it gives you backup.”

Teams are predicting a 60-percent chance of favorable weather for Tuesday’s instantaneous launch window.