Alpha Magnetic Spectrometer to reach Interational Space Station on Final Shuttle Mission. Image Credit/NASA

NASA on Thursday established new target  dates for the launchings of the final shuttle missions. The changes will move the program’s retirement into early 2011.

The changes were made to accommodate work on the payloads of shuttles Discovery and Endeavour.

Discovery’s lift off, earlier listed as mid-September and late October, is now targeted for Nov. 1 at 4:33 p.m., ET.

Endeavour’s lift off, earlier listed as late November, is not targeted for Feb. 26, 2011 at 4:19 p.m., ET.

The late February mission is scheduled to be the shuttle program’s final flight. There remains, however, a possibility that Atlantis could be launched to the International Space Station in the summer of 2011. A decision, which depends in part on new funding, could be made later this summer. Atlantis will be prepared as the rescue shuttle for Endeavour’s late February flight.

Discovery’s six-member crew is slated for an eight-day mission that will deliver spare parts to the station as well as a permanent storage compartment fashioned from the Leonardo multi-purpose logistics module.

Endeavour’s six-member crew will embark on a 10-day mission with more spare parts for the station as well as the Alpha Magnetic Spectrometer, an external international observatory for studies of cosmic rays.