This story was updated on Jan. 5.
The planned predawn launch of the space shuttle Endeavour next month may be the first orbiter flight this year, but it is one of just five remaining missions before NASA is slated to mothball its space plane fleet this fall.
Endeavour is scheduled to blast off on Sunday, Feb. 7 at 4:39 a.m. EDT (0939 GMT) from NASA's Kennedy Space Center in Florida to begin a long-awaited delivery mission flight to the International Space Station. The cargo: a new connecting module and giant bay window for the orbiting laboratory.
The spaceflight will be NASA's 130th mission for the aging shuttle fleet, which has been flying since 1981. Endeavour is due to head out to its launch pad early Wednesday.
NASA currently plans to retire Endeavour and its sister ships Atlantis and Discovery in the fall of this year after completing construction on the $100 billion space station. Their replacement, the capsule-based Orion ship and its Ares I booster, is not slated to begin operational flights until 2015 at the earliest, and potentially later. NASA currently plans to fly astronauts on Russian Soyuz vehicles, and possibly commercial spacecraft, during the interim.
NASA officials said last year that the months of margin to cope with delays between shuttle flights has dwindled to a couple of weeks at the most. But they remain confident that what remains should be enough, barring any unexpected ? and large-scale ? issues in the missions to come.
Here is a glimpse - courtesy of NASA - of the last five missions for the world's only reusable orbital space planes:
5) STS-130: Observation deck in space
NASA's first flight of 2010 promises to give astronauts on the space station a whole new view of their home planet when the shuttle Endeavour delivers the Tranquility module, formerly Node 3. The mission is slated to launch on Feb. 4 with veteran astronaut George Zamka in command.
"This flight will, I think, grab the public's attention," said Kirk Shireman, NASA?s deputy station program manager. "It's just going to be a really, really neat module for those on board."
Tranquility is the module TV comedian Stephen Colbert hoped would bear his name and the last major addition to the station from the United States. The funnyman host of Comedy Central?s Colbert Report even won an online NASA vote to name the module by encouraging fans to write his name in.
In the end, NASA opted to christen the new module after Tranquility Base, the moon base established by Apollo 11 astronauts during the historic first manned ?landing in 1969. However, the Tranquility module will house an exercise treadmill named after Colbert ? a consolation prize from NASA ? and other life support gear.
But Tranquility's main cool factor stems from the seven-window cupola that will serve as an observation portal for astronauts inside the station. The windows will prime views of the station exterior during robotic arm work and spacecraft arrivals and departures.
"The dream of being able to go out and just have an unencumbered view of space ? we'll have it," Shireman said.
4) STS-131: Experiments in orbit
Currently slated to launch on March 18, the shuttle Discovery will carry a cargo pod designed to attach to the space station like an orbital walk-in closet so astronauts can deliver a pantry full of supplies. U.S. Navy Capt. Alan Poindexter will command the mission.
At the heart of Discovery's space station deliveries is a set of experiment racks containing new gear to observe how the bodies of astronauts change in space, as well as observe the Earth far below.
A window observational research platform will add cameras, sensitive scanners and other sensors to the Earth-facing window in order to monitor climate changes, sea formations and crop weather damage on a global scale. An exercise system rack called MARES will also be packed aboard Discovery. It is designed to study how human muscles atrophy in the weightlessness of space by measuring changes in the strength of bones and muscles over time.
Discovery will also deliver a sleeping berth the size of a phone booth that will serve as station astronaut's bedroom, NASA officials have said.
3) STS-132: An international affair
The shuttle Atlantis is expected to end its spaceflying career with the STS-132 mission, a flight that will deliver a new Russian room and European robotic arm to the space station. Navy Capt. Ken Ham will command the flight.
Slated to launch on May 14, the mission will deliver the Mini-Research Module 1 (MRM-1) for Russia's Federal Space Agency. Despite its name, the module will actually be Russia's second small addition to the station since its counterpart, MRM-2, will launch atop an unmanned rocket in Fall 2009. Both mini-research modules will be attached to different parts of the station's Russian-built segment and double as docking ports for Russian spacecraft.
The extra robotic arm aboard Atlantis was built for the station by the European Space Agency (ESA). It is designed to pluck experiments out of a Russian airlock and attach them outside the station, use infrared cameras to inspect the outpost's exterior and help move astronauts into position during spacewalks, according to the ESA officials.
The mission will be the 32nd and final flight for Atlantis.
2) STS-134: The billion-dollar experiment
In a fitting finale, NASA's last space shuttle flight will fly is expected to be one that was never supposed to fly. It is STS-134, an extra mission tacked on to fly a long-awaited Alpha Magnetic Spectrometer, a $1.5 billion particle physics experiment that was shelved after the 2003 Columbia shuttle disaster.
The massive spectrometer weighs a whopping seven tons and is designed to detect cosmic rays and measure their charge, momentum and velocity. The U.S. Department of Energy-led experiment includes 16 international partners. Researchers hope the powerful spectrometer will be able to measure antimatter and the remnants of the theoretical Big Bang that gave birth to the universe.
The mission is slated to launch on Sept. 16 aboard the Discovery orbiter - the oldest remaining shuttle after the tragic losses of Challenger and Columbia in 1986 and 2003, respectively. It will mark an end to what will be just over 29 years of U.S. space shuttle flight.
"I'm sure it will be emotional," NASA's shuttle program manager John Shannon said in a statement. "But I suspect that it will not be sadness over the passing of that era, but happiness that we were a part of it."
The flight will be Discovery's 39th and last mission.
1) STS-133: Spare part bonanza
Endeavour's final flight is expected to ferry more vital spare parts to the International Space Station as well as a cargo pod packed with supplies. The mission is slated to launch on July 29.
"It isn't glamorous, but it's really important for the space station to execute its mission," Shireman said of the flight.
Chief among the shuttle's cargo will be a debris shields for the station's Russian-built Zvezda module and extra antennas for its S-band communications system. Extra circuit breaker boxes, cooling system gear and a spare arm for Canada's maintenance robot Dextre - a multi-limbed mechanical repairman - will also be onboard mission managers said.
The cargo pod, formerly known in NASA parlance as a Multi-Purpose Logistics Module, is expected to be left aboard the station to serve as an extra walk-in closet to store supplies and equipment. It has been refitted to stay in space permanently.
A series of three spacewalks are scheduled to deliver the spare station gear. The mission is also expected to test a new navigation sensor that could be tested on Orion. It will be the 25th mission for Endeavour, which is NASA's youngest orbiter, and will also mark the end of construction for the International Space Station.
Assembly began in 1998 with the launch of Russia's Zarya control module. When complete, the station will contain large rooms and laboratories from the U.S., Russia, Japan and Europe, a robotic arm and maintenance robot from Canada and draw power from a set of expansive solar array that give the orbiting laboratory a wingspan that could cover an American football field.
Even unfinished, the space station can easily be spotted from Earth by the unaided human eye.
"The assembly of the space station could not have been done without the space shuttle, and the assembly of the space station is one of the great engineering achievements of mankind," Shannon said. "So the space shuttle will have done a good job."
- Video Show ? Inside Look: Riding NASA?s Space Shuttles
- Video ? Building the International Space Station
- Image Gallery - Shuttle Discovery's Midnight Launch