[27] STS-134 was planned to be the final regularly scheduled mission of the NASA Space Shuttle Program, but with the passing in 2011 of an appropriations bill authorizing the conversion of STS-335 to STS-135, this was no longer the case.

The AMS-02 unit is a particle physics detector which contains a large permanent magnet, and is designed to search for antimatter and investigate the origin and structure of dark matter.

These ORUs included a High Pressure Gas Tank (HPGT), an Ammonia Tank Assembly (ATA), the S band Antenna Sub-System Assembly #2 & 3 (SASA), a Special Purpose Dextrous Manipulator (SPDM) Arm with Orbital Replacement Unit change-out mechanism, a Space Test Program Houston 3 Department of Defense payload, and a spare ELC pallet controller avionics box.

The crew then guided Endeavour back towards the station, flying a nominal orbiter trajectory for docking to the ISS's Pressurized Mating Adapter-2.

Prior to this, commander Mark Kelly and pilot Greg Johnson completed an engine firing, known as the OMS-2 burn, to circularize the orbit of the shuttle.

This included installing tools such as a center-line camera in the Orbiter Docking System, along with various other sensors used to gauge distance and speed.

The first task for the joint crew was to unberth the Express Logistics Carrier (ELC) 3, and attach it to its final location on the ISS's Port 3 (P3) truss segment.

Express Logistics Carrier 3 was removed from the payload bay of Endeavour by the SRMS and handed off to the Space Station Remote Manipulator System (SSRMS), also known as Canadarm2.

Mike Fincke and Drew Feustel transferred the two Extravehicular Mobility Units (EMU) to the ISS's Quest Airlock in preparation for their use during the mission's four spacewalks.

The campout was done with the airlock's air pressure reduced, so as to purge nitrogen bubbles from the astronauts' blood and thus prevent decompression sickness.

Members of both crews also conducted two in-flight interviews with media on the ground, including PBS NewsHour, National Public Radio, Associated Press, Reuters and Fox News.

On flight day 6, the members of Endeavour's crew performed a focused inspection of an area of thermal protection tiles on the bottom of the orbiter.

The focused inspection started with the Canadarm2 grappling the OBSS in the middle of the boom and handing it off to the shuttle's Canadarm, which was controlled by pilot Greg Johnson and mission specialists Mike Fincke and Roberto Vittori.

Benedict also blessed Mark Kelly's wife Gabby Giffords, who had undergone skull surgery earlier in the week, and offered condolences to Paolo Nespoli for the loss of his mother.

During the spacewalk, Fincke and Feustel hooked up a jumper to transfer 2.3 kg (5 lb) of ammonia to the Port 6 Photovoltaic Thermal Control System (PVTCS), lubricated the Solar Alpha Rotary Joint (SARJ) and one of the "hands" on Dextre, and installed a stowage beam on the Starboard 1 (S1) truss.

Commander Mark Kelly documented the spacewalk with still and video cameras, while mission specialist Greg Chamitoff assisted Feustel and Fincke.

Commander Mark Kelly and mission specialist Mike Fincke conducted an in-flight interview with 400 students from Mesa Verde Elementary School in Tucson, Arizona.

Later in the crew day, STS-134 mission specialist Roberto Vittori and Expedition 27 flight engineer Paolo Nespoli answered questions from Italian President Giorgio Napolitano.

Expedition 27 commander Dmitri Kondratyev and flight engineers Paolo Nespoli and Catherine Coleman left the ISS aboard the Soyuz TMA-20 spacecraft at 21:35 UTC.

Later in the day, commander Mark Kelly and mission specialists Mike Fincke and Chamitoff conducted interviews with The Daily, KDKA, Pittsburgh Tribune-Review and KTRK-TV.

Johnson and mission specialist Roberto Vittori also completed some more equipment transfers between the station and shuttle, and began to clean up and organize the Permanent Multipurpose Module (PMM) Leonardo.

After astronauts Drew Feustel and Mike Fincke exited the Quest Airlock, the pair began installing the Power Data Grapple Fixture (PDGF).

The pair also took pictures of the Zarya module's thrusters and captured some infrared video of an experiment delivered on board the Express Logistics Carrier (ELC) 3.

While the EVA was going on, pilot Greg Johnson and mission specialist Roberto Vittori assisted Expedition 28 flight engineer Ron Garan in stowing new equipment and supplies on the ISS.

[63] On flight day 11, the crew of Space Shuttle Endeavour conducted a late inspection of the orbiter's Thermal Protection System.

[64] The joint Expedition 28/STS-134 crew held a news conference with reporters on the ground at NASA centers around the country and ISS partner agencies.

Astronauts Mike Fincke and Greg Chamitoff spent the night in the Quest Airlock with the air pressure reduced to 10.2 Psi, so as to avoid decompression sickness during their spacewalk.

Mission specialists Mike Fincke and Greg Chamitoff replaced an absorbent bed in the Carbon Dioxide Removal Assembly (CDRA).

While the CDRA work was on-going, commander Mark Kelly and mission specialist Drew Feustel re-sized two of the spacesuits that will be used by Expedition 28 flight engineers Ron Garan and Mike Fossum.

Mission specialist Mike Fincke completed the work on the Carbon Dioxide Removal Assembly (CDRA) that he and Greg Chamitoff had started the day before.