International Space Station (ISS) mission STS-121 ended today when Space Shuttle Discovery touched down at Kennedy Space Center (KSC), Florida at 1314GMT (pictured below). Discovery launched on 4 July and spent just under 13 days in orbit, with almost nine days at the ISS. Discovery delivered supplies, equipment and the new Expedition 13 crew member to the orbital outpost, European Space Agency astronaut Thomas Reiter.
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During the mission's three spacewalks, two of the six STS-121 crew members, British born Piers Sellers and Michael Fossum performed maintenance on the station’s mobile transporter, replaced a pump and tested Orbiter heat shield repair techniques. STS-121 was the 115th shuttle mission and the 18th US visit to the space station. Its landing marked the end of Discovery’s 32nd flight.
At 5min to landing the Orbiter's velocity eases below the speed of sound about 25miles from the runway. As it nears the KSC Shuttle Landing Facility (SLF), the mision commander takes manual control, piloting the vehicle to touchdown on one of two ends of the SLF.
As Discovery would have aligned with the runway, it would have begunn a steep descent with the nose angled as much as 19 degrees down from horizontal. This glide slope is seven times steeper than the average commercial airliner landing. During the final approach, the Orbiter drops toward the runway 20 times faster than a commercial airliner as its rate of descent and airspeed increase. At less than 2,000ft the commander raises the nose and slows the rate of descent in preparation for touchdown. In the final 15s the main and nose landing gear are deployed and locked in place. When the Orbiter's main landing gear hits the runway its travelling at up to 226mph. The drag chute is then deployed and the orbiter coasts to a stop.
Source: Flight International
