On May 14, the Atlantis space shuttle is scheduled to lift off for the last time from Cape Canaveral. This will be the 32nd time in 25 years that the shuttle has flown — but as Space.com reports, there are still several secrets that Atlantis holds. Atlantis’ final mission will carry six astronauts and supplies to the International Space Station. But since the shuttle first flew in 1985, it has compiled a history of interesting experiences. Here are some of the lesser known tidbits of knowledge about the “middle child” of the shuttle fleet.

Robert Pearlman is editor of collectSPACE.com and a regular contributor to Space.com. As he told the site, "Atlantis is kind of the unsung underdog of the space shuttle fleet.” The ship is considered a workhorse and a ferry, as it has flown more missions than any other shuttle to bring equipment and crew into space. This last mission will be the 11th time it has traveled to the International Space Station.

But Atlantis has done far more exciting things than transport. Space.com reports that it was this shuttle that caught the first close-up images of an asteroid hitting a planet. This happened with the comet Shoemaker-Levy 9 hit Jupiter in 1994. The shuttle also cannot plug into the space station as the other shuttles can — this essentially means that it does not have an extension cord. All of the other shuttles have a space station to shuttle power system. But since Atlantis does not, it can only fly in space for up to 14 days.

Atlantis was the last shuttle to visit the Hubble Space Telescope. The crew installed the Cosmic Origins spectrograph and Wide Field Camera 3, which allows astronomers to see the universe as never before. This was the last time additions were made to the Hubble before it was sent on its way into the universe.

The shuttle also has its own clone — the space shuttle Endeavor. When NASA originally constructed Atlantis, they created an entire list of spare parts. This then became Endeavor. When the space shuttle Challenger was lost in 1986, NASA decided to build the space shuttle Endeavor out of these spare parts.   

And in 1989, the shuttle became the first to launch an interplanetary probe when it released the Magellan spacecraft from its cargo bays. The Magellan went on to study more than 98 percent of the surface of Venus, showing that it was marked with crater and volcanoes.

Atlantis’ legacy will be long. As Pearlman adds, "The amount of information we have learned about our inner solar system due to the mission of Atlantis will be one of the long-standing legacies that the space shuttle program will take credit for." 

For further reading:

Space Shuttle Atlantis: Things you didn't know
Experts share cool, little known facts about the iconic shuttle.