Shuttle Atlantis' final mission will include mission commander Chris Ferguson (CR), pilot Doug Hurley (CL), and mission specialists Rex Walheim and Sandy Magnus
Shuttle Atlantis' final mission will include mission commander Chris Ferguson (CR), pilot Doug Hurley (CL), and mission specialists Rex Walheim and Sandy Magnus

The U.S. space agency completed a day-long readiness review of the space shuttle Atlantis and set July 8 as the targeted launch date for its final flight.   It is a historic last mission of the 30-year-old shuttle program.

The space shuttle Atlantis is set to liftoff on July 8 with four crew members aboard on a 12-day mission to resupply the International Space Station.  

NASA says the Atlantis cargo includes science equipment, spare parts, clothing, a year's supply of food and a system so NASA can assess the possibility of robotically refueling satellites in orbit.  And, like a traveler who brings a suitcase packed with gifts only to refill it at her destination, Atlantis will ferry back to Earth completed science experiments, the space station's trash and a cooling pump module that broke last year.

Space Shuttle Program Launch Integration Manager Mike Moses says the resupply mission is important ahead of the shuttle fleet's retirement.  At the moment, the space station has a six-member crew representing Japan, Russia and the United States.   

"We're kind of doing a surge here and pre-stowing a lot of gear up on station to get us another year of lifetime in case we do have some problems with the commercial orbital resupply vehicles that are out there and they get delayed," said Moses. "So this is to try to buy some insurance, but what that does is put the stowage situation on station in a real crunch, so the more we can offload the stuff they don't need, the better."

He said the crew might try to extend the mission to 13 days in order to transfer as much gear as possible.

Under the NASA Authorization bill, which President Barack Obama signed into law last year, the U.S. extended its commitment to the International Space Station to 2020.  But, after the shuttle fleet is retired this year, the United States will no longer have its own means to reach the orbiting laboratory.  NASA will have to rely on Russia and pay for transport flights on Russian Soyuz spacecraft.  Meanwhile, private companies also are working to create spacecraft that can go to the orbiting lab.    

Bill Gerstenmaier, NASA's associate administrator for Space Operations, notes that this space shuttle mission has only a four-member crew, which is smaller than normal.

In the past, another space shuttle has been at the ready to rescue astronauts in case an orbiter failed in space.  Given that this is the last space shuttle mission, there is no back-up shuttle, so NASA will have to rely on Russia's smaller Soyuz crafts in the event of a problem.

Gerstenmaier said NASA has given potential rescue scenarios a lot of thought.    

"Even though we're using a different means to provide crew rescue capability, it's at least as good as what we had with the shuttle," said Gerstenmaier.

After three decades and 134 launches - and counting - Atlantis will be the final shuttle to go into space.

NASA says between 500,000 and 750,000 visitors are expected to flock to the communities near the Kennedy Space Center, along the so-called "Space Coast" in Florida, to watch this historic liftoff.

The 30-year-old shuttle program is being retired so NASA can focus on developing the next generation of spacecraft that could go beyond low-Earth-orbit, possibly to an asteroid or the planet Mars.