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The countdown is on at Kennedy Space Center for tonight's launch of the Space Shuttle Discovery at 9:20pm ET.
After overcoming delays due to safety concerns, Discovery will blast off on a 14-day mission to deliver the last major component of the International Space Station.
After a month of delays, it appears there is now nothing standing in the way of Discovery.
The 18-story spacecraft is poised on the launchpad and scheduled to liftoff in a rare full-moon, night launch tonight.
But for a while it looked like the shuttle might not be going anywhere.
One of three hydrogen gas valves broke during Endeavour's launch last year, so NASA has spent the past months making sure the shuttles were safe to fly.
In the end, engineers decided the valves weren't a big risk and, in the event one does break, shuttle program manager John Shannon says "we showed that if that piece got in the plumbing it was unlikely to cause damage and we showed that even if it does cause damage, that damage was not something we needed to worry about"
Even the seven astronauts who will be strapped in to Discovery tonight aren't worried about their safety.
Shuttle Commander Lee Archambault says "we're very happy it has been resolved successfully, we're ready to get going."
When Discovery does liftoff it will deliver the last set of solar wings to the space station. When unfurled, like this set in 2006, it should give the orbiting outpost full power and leave it one step closer to completion as the shuttles move one launch closer to retirement.
Discovery will also carry the first Japanese astronaut to live aboard the space station and will bring home American Sandra Magnus who has been living in space since November as well as a fix for that machine that is supposed to convert urine to drinking water. Turns out the one they brought up in November has been malfunctioning.
