LAUNCHED: 6:21 a.m. -- Full story & video | Photo gallery
STATUS: Mission complete

Space shuttle Discovery made its second-to-last flight in April.  STS-131 carried the 'Leonardo' multi-purpose cargo module to the space station.  The mission also removed and replaced an ammonia tank assembly outside the station.

Three spacewalks took place during the 13-day mission, which was Discovery's 38th flight.  Seven astronauts were on board, including a former teacher.

According to the current schedule, this will have been the last launch to take place in darkness, occurring a half-hour before sunrise.

LAUNCHED: 2:20 p.m. -- Full story & video | Photo gallery
STATUS: Mission complete

STS-132 was the 32nd and last planned mission for space shuttle Atlantis.  The flight to the international space station delivered a Russian mini-module along with a radiator, airlock, and other parts.

Three spacewalks were successfully completed to store spare parts outside the station, including six batteries, antenna parts, and spares for the robotic arm.

Six astronauts made the trip.

Scheduled launch time: 4:33 p.m.

This will be the final flight for Discovery, the fleet's most experienced orbiter.

Discovery will deliver and install the Pressurized Multipurpose Module, an adapted cargo carrier that will primarily be used for storage of spares, supplies, and waste on the station.

Six astronauts will fly the STS-133 mission, including Clearwater's Nicole Stott.

NASA is expected to make the launch date official at a July 1 meeting.

Scheduled launch time: 4:19 p.m.

Space shuttle Endeavour is now planned to make the program's final flight, the STS-134 mission.  It is an extra flight added last year specifically to deliver the Alpha Magnetic Spectrometer to the station.

The Alpha Magnetic Spectrometer is a particle physics experiment module that will help researchers study the formation of the universe and search for evidence of dark matter and antimatter.

Six astronauts have been tapped for the 10-day mission, which was originally scheduled for September but delayed by problems with the Alpha Magnetic Spectrometer.

NASA is expected to make the launch date official at a July 1 meeting.