Original sentence: ExPRESS Logistics Carrier 4 (ELC-4).It will be the final flight of Space Shuttle Endeavour, and is currently planned to be the final flight of the Space Shuttle program.Multi-Purpose Logistics Module (to be left permanently attached to the ISS, whereupon it will become a PLM - Pressurised Logistics Module).STS-133 (ISS assembly flight ULF5) is a mission of the  to visit the International Space Station, scheduled to fly no earlier than Sep 16, 2010.STS-133 will leave its MPLM permanently attached to the ISS (whereupon it will become a PLM - Pressurised Logistics Module).The mission will deliver an MPLM to the International Space Station, and the fourth ExPRESS Logistics Carrier
Edited sentence: ExPRESS Logistics Carrier 3 (ELC3).However, final approval is needed before a firm launch date is set.Multi-Purpose Logistics Module Leonardo.NASA is considering other possible options for the STS-133 mission.NASA management is currently studying the possibility of leaving the Orbiter Boom Sensor System (OBSS) permanently attached to the station after the last shuttle mission.One of the missions is expected to be moved to a later date, and it is expected STS-134 will launch on July 29 and STS-133 will launch sometime in September on the last mission of the Space Shuttle program.STS-133 (ISS assembly flight ULF5) is a mission of the  to visit the International Space Station, scheduled to fly no earlier than July 29, 2010.STS-133 is slated to be the final flight of the Space Shuttle program.STS-133 would mark the completion of the International Space Station, and the final flight of Endeavour.The feasibility of leaving the OBSS attached to ISS for a long period of time has also been demonstrated when the STS-123 mission left it behind for use by STS-124 two months later.The mission has been given a NET launch date of July 29, 2010, which is the same launch date as STS-134.The mission will deliver the final components of the International Space Station, and the third and fourth ExPRESS Logistics Carriers.The usefulness of having the OBSS available for use at the station was demonstrated during Scott Parazynski's repair of the torn P6 solar panel on STS-120.These options would be possible because for its last flight the orbiter could be modified to maximize the available payload mass