Morning breaks over Launch Pad 39A at NASA's Kennedy Space Center in Florida following the arrival of space shuttle Atlantis in preparation for its final flight, the STS-132 mission in May 2010.

On Friday, the Atlantis spaceshuttle is scheduled to blast off for its 32nd and last mission, but even after25 years of spaceflight this middle child of NASA's current space plane fleetstill has its secrets.

Atlantiswas named after the original exploration sailing vessel of the Woods HoleOceanographic Institute, which brought scientists discoveries in oceanographyand marine biology during its many adventures on the seas. Living up to itsnamesake, the Atlantis shuttle has ventured into the unknown and returned with trovesof scientific information since its first mission in 1985.

To prepare for what is expected to be the shuttle's final mission, here are seven cool things youdidn't know about Atlantis:

1) It's the workhorse ofthe shuttle fleet.

"Atlantis is kind of theunsung underdog of the space shuttle fleet," said Robert Pearlman, editorof collectSPACE.com, an online publication and community for space history andartifact enthusiasts, and a SPACE.com contributor.

Atlantis is considered the workhorseand the ferry because it has flown so many missions bringing crews to spacestations and equipment into orbit. Atlantis flew to the Mir spacestation seven times, and will have flown to the International Space Station11 times, including this last mission.

2) Atlantis was the firstshuttle to launch an interplanetary probe.

During a four-day mission in1989, astronauts launched the Magellan spacecraft from the cargo bay ofAtlantis.

It was the first time aninterplanetary probe was launched from a space shuttle. Magellan mapped morethan 98 percent of the surface of Venus, and revealed the planet to be mostlycovered by volcanic materials, dotted with a few impact craters.

3) It helped NASA to see acomet smack into a planet.

In October 1989, the Galileoprobe was launched from Atlantis to study Jupiter. Galileo captured the firstclose-up images of an asteroid while on its way to the giant planet. Then, itmade the only direct observations of a comet colliding with a planet when itcaught the 1994 impact of comet Shoemaker-Levy 9 on Jupiter.

"The amount ofinformation we have learned about our inner solar system due to the mission ofAtlantis will be one of the long-standing legacies that the space shuttleprogram will take credit for," Pearlman said.

4) It doesn't have anextension cord.

Unlike the other shuttles,Atlantis does not have a spacestation to shuttle power system that would allow the shuttle to tap intothe solar-powered electrical system of the space station while docked. Atlantismust rely solely on the hydrogen-oxygen fuel cells which are carried onboard,and because of this Atlantis missions are limited to a maximum of about 14days. The other shuttles can stay in space longer.

5) Atlantis has a spaceshipclone.

"The shuttle Endeavourexists because of Atlantis," Pearlman said. When NASA built Atlantis, theydecided to make a complete set of spare parts, with the idea that if anyshuttle was damaged, it could easily be repaired.

However, after the Challengershuttle was lost in an explosion in 1986, there was debate about what to do. Itwas decided, Pearlman said, to build the Endeavour shuttle out of the spareAtlantis parts. Endeavour is scheduled to fly thelast mission of the space shuttle program in November of this year.

6) It was the last shuttleto visit the Hubble Space Telescope.

During a May 2009 mission,the Atlantis crew made 5 space walks to repair and add equipment to the Hubble.

Among the upgrades, the crewinstalled the CosmicOrigins spectrograph, an instrument designed to allow Hubble to peerfarther into the universe in the ultraviolet light spectrum than ever before,and Wide Field Camera 3, which allows astronomersto better observe galaxy evolution, dark matter and dark energy. Theconclusion of the mission was the last time that repairs or additions will bemade to the Hubble.

7) Atlantis co-starred ina movie with Leonardo DiCaprio.

IMAX cameras made the tripwith the Atlantis crew in 2009 on its mission to upgrade the Hubble SpaceTelescope. In March of this year, "Hubble 3D" was released, withLeonardo DiCaprio narrating.

Atlantis and its finalastronaut crew, a veteran six-man team, will deliver a new Russian sciencemodule called Rassvet (Russian for "Dawn") to the space station onthe shuttle's final mission. Liftoff of Atlantis is currently set for Friday at2:20 p.m. EDT (1820 GMT) from NASA's Kennedy Space Center.

The mission is NASA's 132ndspace shuttle flight since the fleet began launching into space in April 1981.After this mission, only two more shuttle flights remain, on Discovery andEndeavour, before NASA retires its three-orbiter fleet later this year.