People in the eastern United States will get a great opportunity, weather permitting, to see the space shuttle Discovery launched into orbit early Tuesday morning. And it might also be the final opportunity ever to see a nighttime shuttle launch.

This flight (STS-128) will be the 30th to rendezvous and dock with the International Space Station (ISS), and the glow of the shuttle's engines will be visible along much of the Eastern Seaboard. A SPACE.com map shows the area of visibility.

To reach the space station, Discovery must be launched when Earth's rotation carries the launch pad into the plane of the station's orbit. For mission STS-128, that will happen at 1:36:05 a.m. ET on Tuesday, resulting (if all goes as planned) in NASA's second nighttime launch of a space shuttle in 2009 (the most recent was March 15).

As has been the case with other launches to the ISS, Tuesday's liftoff will bring the shuttle's path nearly parallel to the U.S. East Coast.

After STS-128, there could only be just six more flights left before the shuttle program finally comes to a close (tentatively set for September 2010). Of those six remaining flights, five are to be launched during the midday or morning hours. One mission, STS-130, involving shuttle Endeavour is currently scheduled to be launched just before sunrise on Feb. 4. That launch would come during morning twilight, but unless it's delayed, or if the current launch schedule significantly changes, this week's predawn launch of Discovery could be the very last time a shuttle is launched in total darkness.

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