There's a three-hour window in case weather or other complications delay the test. Don't expect this particular vehicle to carry forward -- it's not poised to survive.

If all goes well, Starliner will join SpaceX's Crew Dragon and other vehicles as part of NASA's Commercial Crew program, which aims to have American vehicles once more carrying American astronauts into space through cooperation with private spaceflight outfits. On top of boosting national pride, it would reduce dependence on Russia for those missions where cooperation isn't necessary.