that the MPLM won't get stuck, and also to ensure correct capture of the HTV. September 6 (Flight Day 10 – Off duty) Flight day 10 saw the joint crews transfer samples from the space station to the shuttle freezer known as Glacier. The samples will be returned to Earth for examination by scientists who will develop ways to prevent bone and muscle loss in space as well as cures for other illnesses on Earth. The crews also completed some close outs of the Multi-Purpose Logistics Module Leonardo. The last portion of the crew day was spent off duty. September 7 (Flight Day 11 – Hatch closure) On flight day 11, the joint ISS/shuttle crews completed transfers and closed the hatches with the MPLM. Once the hatches were closed, the MPLM was deactivated, demated and berthed back in the payload bay of the space shuttle. During this process, José M. Hernández and Nicole Stott took part in a PAO event. The end of the crews work days saw the two crews say goodbye in a farewell ceremony and close the hatches between the shuttle and ISS. Once the hatches were closed, the Pressurized Mating Adapter 2 was depressurized, in advance of undocking. The shuttle crew setup and checked out the rendezvous tools before going to bed. September 8 (Flight Day 12 – Undocking) On flight day 12, Space Shuttle Discovery successfully undocked from the International Space Station at 19:26 UTC. After undocking, the shuttle backed out and performed a fly around of the ISS. The Space Shuttle then performed two separation burns using its thrusters. After the separation burns, astronauts Kevin Ford, José M. Hernández, and Christer Fuglesang used the Orbiter Boom Sensor System (OBSS) to inspect the shuttle's Thermal Protection System (TPS). When they completed that task, the OBSS was berthed on the starboard sill of the payload bay and the Shuttle Remote Manipulator System (SRMS) was powered down. September 9 (Flight Day 13 – End of mission prep) On flight day 13, the Space Shuttle crew began stowing items for landing. During the course of the day, commander Frederick W. Sturckow and pilot Kevin A. Ford performed standard checks of the Flight Control Systems (FCS), Reaction Control System (RCS) jets, and communications with the ground. The crew also deactivated the Wing Leading Edge System (WLES), stowed the Ku-band antenna, and reviewed landing procedures. September 10 (Flight Day 14