Space Shuttle Atlantis will make its final spaceflight today, launching from Kennedy Space Center in FL at 2:20 p.m. EDT. The shuttle is headed to the International Space Station for a 12-day mission that includes leaving behind a small Russian research module, batteries, a dish antenna, and other spare station parts. Atlantis will also carry and return with it a microorganism experiment from Rensselaer Polytechnic Institute that will study the effects of microgravity on the formation of bacteria that could harm astronauts. The flight is the shuttle’s 32nd trip to space and will conclude its 25-year career.

Atlantis is one of three remaining orbiters in NASA’s space shuttle fleet, and was the fourth shuttle built. It is being retired to make room for a new launch vehicle–just what vehicle that will be is still being decided. President Obama released a new budget proposal in January that canceled the development of the Ares rocket, intended to be the shuttle’s successor. Instead, his plan calls for the commercial sector to build vehicles for low earth orbit missions and NASA to focus on developing a heavy lift spacecraft that can take astronauts beyond, to the moon, asteroids, the moon of Mars, and Mars itself.

Space Shuttle Atlantis has made many remarkable missions, including being the first shuttle to launch an interplanetary probe and the last shuttle to visit to the Hubble Space Telescope. It has even been a “movie star”–its Hubble mission was made into a 3D movie narrated by actor Leonardo DiCaprio.

Atlantis’ mission today 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.

*Update 2:30 p.m.: Space Shuttle Atlantis has successfully launched.