On Friday, the Atlantis space shuttle is scheduled to blast off for its 32nd and last mission, but even after 25 years of spaceflight this middle child of NASA's current space plane fleet still has its secrets.
Atlantis was named after the original exploration sailing vessel of the Woods Hole Oceanographic Institute, which brought scientists discoveries in oceanography and marine biology during its many adventures on the seas. Living up to its namesake, the Atlantis shuttle has ventured into the unknown and returned with troves of 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 you didn't know about Atlantis:
1) It's the workhorse of the shuttle fleet.
"Atlantis is kind of the unsung underdog of the space shuttle fleet," said Robert Pearlman, editor of collectSPACE.com, an online publication and community for space history and artifact enthusiasts, and a contributor to SPACE.com, a sister site to Life's Little Mysteries.
Atlantis is considered the workhorse and the ferry because it has flown so many missions bringing crews to space stations and equipment into orbit. Atlantis flew to the Mir space station seven times, and will have flown to the International Space Station 11 times, including this last mission.
2) Atlantis was the first shuttle to launch an interplanetary probe.
During a four-day mission in 1989, astronauts launched the Magellan spacecraft from the cargo bay of Atlantis.
It was the first time an interplanetary probe was launched from a space shuttle. Magellan mapped more than 98 percent of the surface of Venus, and revealed the planet to be mostly covered by volcanic materials, dotted with a few impact craters.
3) It helped NASA to see a comet smack into a planet.
In October 1989, the Galileo probe was launched from Atlantis to study Jupiter. Galileo captured the first close-up images of an asteroid while on its way to the giant planet. Then, it made the only direct observations of a comet colliding with a planet when it caught the 1994 impact of comet Shoemaker-Levy 9 on Jupiter.
"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," Pearlman said.
4) It doesn't have an extension cord.
Unlike the other shuttles, Atlantis does not have a space station to shuttle power system that would allow the shuttle to tap into the solar-powered electrical system of the space station while docked. Atlantis must 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 14 days. The other shuttles can stay in space longer.
5) Atlantis has a spaceship clone.
"The shuttle Endeavour exists because of Atlantis," Pearlman said. When NASA built Atlantis, they decided to make a complete set of spare parts, with the idea that if any shuttle was damaged, it could easily be repaired.
However, after the Challenger shuttle was lost in an explosion in 1986, there was debate about what to do. It was decided, Pearlman said, to build the Endeavour shuttle out of the spare Atlantis parts. Endeavour is scheduled to fly the last mission of the space shuttle program in November of this year.
6) It was the last shuttle to 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 crew installed the Cosmic Origins spectrograph, an instrument designed to allow Hubble to peer farther into the universe in the ultraviolet light spectrum than ever before, and Wide Field Camera 3, which allows astronomers to better observe galaxy evolution, dark matter and dark energy. The conclusion of the mission was the last time that repairs or additions will be made to the Hubble.
7) Atlantis co-starred in a movie with Leonardo DiCaprio.
IMAX cameras made the trip with the Atlantis crew in 2009 on its mission to upgrade the Hubble Space Telescope. In March of this year, "Hubble 3D" was released, with Leonardo DiCaprio narrating.
Atlantis and its final astronaut crew, a veteran six-man team, will deliver a new Russian science module called Rassvet (Russian for "Dawn") to the space station on the shuttle's final mission. Liftoff of Atlantis is currently set for Friday at 2:20 p.m. EDT (1820 GMT) from NASA's Kennedy Space Center.
The mission is NASA's 132nd space shuttle flight since the fleet began launching into space in April 1981. After this mission, only two more shuttle flights remain, on Discovery and Endeavour, before NASA retires its three-orbiter fleet later this year.