Space shuttle Atlantis lifts-off from the Kennedy Space Center at Cape Canaveral, Fla. Friday May 14, 2010. Atlantis' 12-day mission will deliver a Russian built storage and docking module to the International Space Station.
NASA managers cleared space shuttle Atlantis on Tuesday for a July 8 launch, approving it for a cargo run to the International Space Station and the final flight in the 30-year-old shuttle program.
Lift-off of the shuttle manned by a minimal crew of four astronauts is set for 11:26 a.m. ET from the Kennedy Space Center in Florida.
The 12-day flight was added to the shuttle's schedule last year to buy time in case NASA's newly hired cargo delivery companies have problems getting their spacecraft into orbit.
Atlantis will be delivering a year's worth of food, clothing, science equipment and supplies to the orbital outpost, a $100-billion (U.S.) project of 16 nations that circles 354 kilometres above Earth.
"This flight is incredibly important to the space station. The cargo that is coming up on this flight is really mandatory," said NASA's spaceflight chief Bill Gerstenmaier.
Earlier on Tuesday, the threat of an orbital debris impact interrupted the station's preparations for Atlantis's visit. NASA learned that an unidentified piece of space debris was likely to pass close to the station and told the crew to seek shelter in the station's two Russian Soyuz escape capsules.
Typically, the station manoeuvres to avoid potential debris impacts, but the notice came just 14 hours before the closest approach, too late to plan and conduct an avoidance manoeuvre.
"We think it came within about 335 meters of the space station. It was probably the closest object that's actually come by space station," Mr. Gerstenmaier said.
The six station crew members divided into two groups of three and sealed themselves into the Soyuz capsules about 20 minutes before the object came closest to the station, which occurred at 8:08 a.m. ET. It was only the second time in the station's history that crews had to seek shelter in their "lifeboats" for an orbital debris threat.
The station's two U.S. crewmembers are preparing for a spacewalk during shuttle's Atlantis' eight-day stay, a job normally undertaken by the visiting astronauts.
NASA, however, has been trying to keep the Atlantis crew's training as simple as possible, as the four shuttle astronauts already are tasked to do the work of the six or seven people normally assigned to shuttle flights.
The U.S. space agency pared down the crew size to accommodate the smaller Russian Soyuz spacecraft that would be used to fly the Atlantis astronauts home in case the shuttle is too damaged to attempt landing.
Since the 2003 Columbia accident, NASA has had a second shuttle on standby for a rescue mission if needed. Atlantis, however, is the 135th and last shuttle to fly, with no backup shuttle in waiting.
The United States is ending the shuttle program to save its $4-billion annual operating costs and use the money to develop spaceships that can travel beyond the station, such as to the moon, asteroids and eventually to Mars.
Space Exploration Technologies and Orbital Sciences Corp. are scheduled to begin cargo deliveries to the station next year. NASA is hoping commercial companies will be able to fly astronauts as well, though those spaceships are not expected to be ready for at least four to five years.
In the meantime, NASA will pay Russia to fly its astronauts to the station at a cost of more than $50-million a person.
Reuters