Greg H. Johnson and Mark Kelly check out the nose of space shuttle Endeavour following the return to NASA's Kennedy Space Center.

STS-134 Pilot Greg H. Johnson, left, and Commander Mark Kelly check out the nose of space shuttle Endeavour following the successful return to NASA's Kennedy Space Center in Florida. Endeavour's final return from space completed the 16-day, 6.5-million-mile STS-134 mission. Main gear touchdown on the Shuttle Landing Facility's Runway 15 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. STS-134 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/Kim Shiflett