(Image source: Popular Science)

BY: STEVEN SPARKMAN

The shuttle Atlantis successfully launched Friday morning after a nail-biter of a countdown.

Weather was the main concern, with two lightning strikes hitting dangerously close to the launch pad the day before. But as Popular Science notes -- the rain let up just enough to let the shuttle get off the ground.

“The sudden, sunny triumph over a 30%-favorable weather forecast added to what was already an incredibly emotional scene here by the big countdown clock … With 45 minutes until the 10-minute launch window, weather conditions were given a thumbs up by NASA officials, and it stayed that way." 

In a tense moment, the countdown clock paused at T-31 seconds.

Normally, an error at that moment would have reset the clock to five minutes, but that large a delay would have stalled Atlantis past the launch window. The hold was caused by the oxygen vent arm, or the “Beanie Cap,” but once it was verified to be out of the way, the countdown continued.

Finally, at 11:29 eastern time, the last shuttle mission took off-- visible for about 40 seconds before disappearing into the clouds. (Video source: Spaceflight Now)

Despite the rainy weather and the strong chance of a delay, huge crowds turned out to see Atlantis take off. The Space Coast Office of Tourism estimated a million people watched the beginning of the last shuttle flight. (Image sources: Florida 511, CNN, Universe Today)

Though Atlantis is off the ground, it still isn’t in the clear. There’s no backup shuttle to send after them if they have technical problems. If anything goes wrong, some of the crew will be stuck on the International Space Station for nearly a year. CBS News explains.

“Russia will supply the rescue vessels for Ferguson and his crew if Atlantis ends up severely damaged in flight. But the Russian spaceships can carry only three people, including two crew members, and any rescue would require a series of back-and-forth trips. That is why only four astronauts are flying Atlantis, the smallest crew in decades." 

So what’s next for American spaceflight? Javascript guru Thomas Fuchs joked that if you watch NASA backwards, it’s the story of an agency that can’t do spaceflight, then does low-Earth orbit missions, then goes to the moon. But NASA’s administrator Charles Bolden says the agency will take command of the skies again... just not for a few years.

“Some say that this final shuttle mission will mark the end of America’s 50 years of dominance in human space flight. As a former astronaut, and the current NASA administrator, I want to make clear that American leadership in space will continue for at least the next half century because we’ve laid the foundation for success. And for us at NASA -- failure is not an option." 

Transcript by Newsy.