CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. In the background is the massive Vehicle Assembly Building. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls shuttle Endeavour into Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- Workers accompany shuttle Endeavour as a "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- Workers accompany shuttle Endeavour as a "towback" vehicle slowly pulls it into Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls shuttle Endeavour from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls shuttle Endeavour into Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, space shuttle Endeavour's "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- In the early morning hours after landing, media photograph space shuttle Endeavour as a "towback" vehicle slowly pulls it from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls shuttle Endeavour from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. In the background is the massive Vehicle Assembly Building. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller

CAPE CANAVERAL, Fla. -- A "towback" vehicle slowly pulls shuttle Endeavour from the Shuttle Landing Facility to Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. A purge unit that pumps conditioned air into a shuttle after landing is connected to Endeavour's aft end. In the background is the massive Vehicle Assembly Building. Once inside the processing facility, Endeavour will be prepared for future public display. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown was at 2:34:51 a.m. EDT, followed by nose gear touchdown at 2:35:04 a.m., and wheelstop at 2:35:36 a.m. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Jack Pfaller