Original sentence: ExPRESS Logistics Carrier 3 (ELC-3).However, as NASA have now elected to switch the STS-133 and STS-134 missions around, STS-133 will be the final mission of the Space Shuttle Program.It is currently planned to be the final flight of the Space Shuttle Discovery.Originally, STS-134 was scheduled to be the final mission of the Space Shuttle Program, launching in September 2010.STS-134 is a planned Space Shuttle mission with  that will deliver the Alpha Magnetic Spectrometer and the third ExPRESS Logistics Carrier to the International Space Station.STS-134's LON mission, a contingency mission to rescue a stranded STS-134 crew, will be the Space Shuttle Endeavour, on its STS-133 mission
Edited sentence: A decision will be made as to which one will fly in July and the other mission will launch in September.ExPRESS Logistics Carrier (ELC-3).However, final approval is needed before a firm launch date is set.It is currently slated to be the final flight of the Space Shuttle program.One of the missions is expected to be moved to a later date, and it is expected STS-134 will launch on July 29.STS-134 has been base lined (planned) to launch on July 29, 2010.STS-134 is a planned Space Shuttle mission with  that will deliver the Alpha Magnetic Spectrometer and a fourth ExPRESS Logistics Carrier to the International Space Station.STS-134's LON mission, a contigency mission to rescue a stranded STS-134 crew, is numbered STS-135.The mission has been given a NET launch date of July 29, 2010, which is the same launch date as STS-133, but officially remains scheduled for September 16.The primary payload would be the Alpha Magnetic Spectrometer.This however is in conflict with STS-133, which has a similar launch date