Top 10 Space Stories of 2011

1. The Space Shuttle Era Ends

When Space Shuttle Atlantis landed at Kennedy Space Center just before dawn on July 21, 2011, it marked the end of NASA's Space Shuttle program. The shuttle was the space agency's No. 1 space vehicle for 30 years, with numerous successes under its belt -- notably the deployment and repair of the Hubble Space Telescope and construction of the International Space Station.

The shuttles themselves, however, were notoriously more complex and expensive than they were ever intended to be. They also unfortunately suffered from reliability issues, leading to the tragic destruction of two shuttles, Challenger and Columbia.

Despite its issues, the shuttle continued to serve well past its sell-by date, becoming a pop-culture icon along the way. In its last year of operation, the shuttle also finished one of its key tasks: complete assembly of the International Space Station. It's certainly earned its retirement, which the orbiters spend in numerous museums throughout the country.

Click here to view this gallery.

2011 will go down as a landmark year for space exploration, for a multitude of reasons. From end-of-an-era missions to incredible milestones to breathtaking discoveries, human civilization is reaching out further and more often than ever before from our pale blue dot in the universe.

The vast interstellar distances suddenly looked a lot smaller this year as we were captivated with discovery after discovery of planets ! in other solar systems, while man-made vehicles took their first steps exiting ours. We took a moment to celebrate a half-century of manned space flight just as its torch was being passed from public to private enterprise here in the States. Through it all, NASA and others cleverly used the Web and social media to keep is informed and enthralled.

There were space stumbles, too. The promising and innovative successor to the Hubble Space Telescope was in danger of being scrapped amid budget cutbacks. For a few months there, it felt like satellites were constantly falling from the sky, a new danger the planet didnt need. The sun entering a particularly active cycle meant renewed threats of solar flares to anything in orbit.

Although humankinds problems in space are real and need solutions, they also serve as an encouraging reminder that were there. Those issues are only issues because we dare to brave the final frontier regularly in our quest to better ourselves and expand our knowledge of the universe. The deeper we venture into space, the more out civilization will be affected by it.

Here are Mashables picks for the top space stories of 2011.

More About: Hubble, ISS, James Webb, Mars rover, NASA, orion, space, Space Flight, space shuttle