2011 American crewed spaceflight to the ISS and final flight of the Space Shuttle program
STS-135 (ISS assembly flight ULF7) was the 135th and final mission of the American Space Shuttle program. It used the orbiter "Atlantis" and hardware originally processed for the STS-335 contingency mission, which was not flown. STS-135 launched on July 8, 2011, and landed on July 21, 2011, following a one-day mission extension. The four-person crew was the smallest of any shuttle mission since STS-6 in April 1983. The mission's primary cargo was the Multi-Purpose Logistics Module (MPLM) "Raffaello" and a Lightweight Multi-Purpose Carrier (LMC), which were delivered to the International Space Station (ISS). The flight of "Raffaello" marked the only time that "Atlantis" carried an MPLM.
Although the mission was authorized, it initially had no appropriation in the NASA budget, raising questions about whether the mission would fly. On January 20, 2011, program managers changed STS-335 to STS-135 on the flight manifest. This allowed for training and other mission specific preparations. On February 13, 2011, program managers told their workforce that STS-135 would fly regardless of the funding situation via a continuing resolution. Until this point, there had been no official references to the STS-135 mission in NASA documentation for the general public.
During an address at the Marshall Space Flight Center on November 16, 2010, NASA administrator Charles Bolden said that the agency needed to fly STS-135 to the station in 2011 due to possible delays in the development of commercial rockets and spacecraft designed to transport cargo to the ISS. "We are hoping to fly a third shuttle mission (in addition to STS-133 and STS-134) in June 2011, what everybody calls the launch-on-need mission... and that's really needed to [buy down] the risk for the development time for commercial cargo", Bolden said.
The mission was included in NASA's 2011 authorization, which was signed into law on October 11, 2010, but funding remained dependent on a subsequent appropriations bill. United Space Alliance signed a contract extension for the mission, along with STS-134; the contract contained six one-month options with NASA in order to support continuing operations.
The federal budget approved in April 2011 called for US$5.5 billion for NASA's space operations division, including the shuttle and space station programs. According to NASA, the budget running through September 30, 2011, ended all concerns about funding the STS-135 mission.
Crew.
NASA announced the STS-335/135 crew on September 14, 2010. Only four astronauts were assigned to this mission, versus the normal six or seven, because there were no other shuttles available for a rescue following the retirement of "Discovery" and "Endeavour." If the shuttle was seriously damaged in orbit, the crew would have moved into the International Space Station and returned in Russian Soyuz capsules, one at a time, over the course of a year. All STS-135 crew members were custom-fitted for a Russian Sokol space suit and molded Soyuz seat liner for this possibility. The reduced crew size also allowed the mission to maximize the payload carried to the ISS. It was the only time that a Shuttle crew of four flew to the ISS. The last shuttle mission to fly with just four crew members occurred 28 years earlier: STS-6 on April 4, 1983, aboard Space Shuttle "99".
Funding.
With support from both the House of Representatives and the Senate, the fate of STS-135 ultimately depended on whether lawmakers could agree to fund converting the mission from launch-on-need to an actual flight. On July 15, 2010, a Senate committee passed the 2010 NASA reauthorization bill, authored by Senator Bill Nelson (D-FL), to direct NASA to fly an extra Space Shuttle mission (STS-135) pending a review of safety concerns. The bill still needed the approval of the full Senate. A draft NASA reauthorization bill considered by the House Science &amp; Technology Committee did not provide for an extra shuttle mission. On July 22, 2010, during a meeting of the House Science Committee, U.S. Rep. Suzanne Kosmas (D-FL) successfully amended the House version of the bill to add an additional shuttle mission to the manifest.
On August 5, 2010, the Senate passed its version of the NASA reauthorization bill, just before lawmakers left for the traditional August recess. On August 20, 2010, NASA managers approved STS-135 mission planning targeting a June 28, 2011, launch. On September 29, 2010, the House of Representatives approved the Senate-passed bill on a 304–118 vote. The bill, approved by the U.S. Congress, went to President Barack Obama for his signature.
On October 11, 2010, Obama signed the legislation into law, allowing NASA to move forward with STS-135, though without specific funding. Generally, the average cost of a shuttle mission was about $450 million.
On January 20, 2011, STS-135's designation was officially changed from STS-335. On February 14, 2011, NASA managers announced that STS-135 would fly regardless of the funding situation in Congress.
Payload.
STS-135 delivered supplies and equipment to provision the space station through 2012, following the end of NASA's Space Shuttle program. Since the ISS program was extended to 2024 (now 2030), the station is resupplied by the Commercial Orbital Transportation Services program which took over resupply missions from the Shuttle. A shuttle extension beyond STS-135 wasn't seriously considered, and an ISS extension was never intended to be a guaranteed shuttle program extension, and the Shuttle program officially ended after STS-135.
Multi-Purpose Logistics Module.
The Multi-Purpose Logistics Module (MPLM) "Raffaello" made up the majority of the payload. This was "Raffaello"'s fourth trip to the International Space Station since 2001 and the 12th use of an MPLM. Unlike previous MPLM missions that delivered large compartments and devices to outfit the space station laboratories, STS-135 delivered only bags and supply containers. The MPLM was filled with 16 resupply racks, which is the maximum that it could handle. Eight Resupply Stowage Platforms (RSPs), two Integrated Stowage Platforms (ISPs), six Resupply Stowage Racks (RSRs) and one Zero-G Stowage Rack (ZSR), which sits above another rack during transport.
On flight day 4, "Raffaello" was lifted out of "Atlantis"'s payload bay using the station's Canadarm2. It was berthed to nadir port of the "Harmony" node. After completing the cargo transfers to the ISS, "Raffaello" was loaded with almost of unneeded equipment and station waste to be brought back to Earth. On flight day 11, the MPLM was detached from "Harmony" and was secured in the cargo bay of the shuttle.
Lightweight Multi-Purpose Carrier.
The Lightweight Multi-Purpose Carrier (LMC) was also carried on STS-135. The External Thermal Cooling System (ETCS) Pump Module (PM) stored on ESP-2, which failed and was replaced on orbit in August 2010, rode home on the LMC so that a failure analysis can be performed on the ground. The Robotic Refueling Mission rode up to the station on the underside of the LMC and was placed onto the ELC-4.
Robotic Refueling Mission.
"Atlantis" carried the Robotic Refueling Mission (RRM) developed by the Satellite Servicing Capabilities project at the Goddard Space Flight Center (GSFC). It planned to demonstrate the technology and tools to refuel satellites in orbit by robotic means. After the proof of concept, the long-term goal of NASA is to transfer the technology to the commercial sector.
RRM included four tools, each with electronics and two cameras and lights. Additionally, it had pumps and controllers and electrical systems such as electrical valves and sensors.
The RRM payload was transported to the Kennedy Space Center in early March 2011, where the GSFC team performed the final preparations for space flight.
Once up on the International Space Station, RRM will be installed into the ELC-4. The Dextre robot was planned to be used in 2012 and 2013 during the refueling demonstration experiments.
Picosatellite Solar Cell Testbed 2.
Space Shuttle "Atlantis" carried a miniaturised satellite known as PSSC-2, or Picosatellite Solar Cell Testbed 2 into orbit. PSSC-2 was successfully deployed from the shuttle's cargo bay on flight day 13, becoming the 180th and last Space Shuttle payload to be placed into orbit.
TriDAR.
The mission was the third flight of the TriDAR sensor package designated DTO-701A (Detailed Test Objective), a 3D dual-sensing laser camera, intended for use as an autonomous rendezvous and docking sensor. It was developed by Neptec Design Group and funded by NASA and the Canadian Space Agency. TriDAR had previously flown on STS-128 and STS-131, aboard Space Shuttle "Discovery". TriDAR provides guidance information that can be used for rendezvous and docking operations in orbit, planetary landings and vehicle inspection/navigation of robotic rovers. It does not rely on any reference markers, such as reflectors, positioned on the target spacecraft, instead using a laser-based 3D sensor and a thermal imager. Geometric information contained in successive 3D images is matched against the known shape of the target object to calculate its position and orientation in real-time.
The sensor was emplaced on the exterior airlock truss next to a Trajectory Control System (TCS) sensor. The TriDAR hardware was installed in "Atlantis"'s payload bay on April 6, 2011. On STS-135, TriDAR was used to demonstrate technology for autonomous rendezvous and docking in orbit.
Down-mass payload.
STS-135 returned to Earth carrying several items of downmass payload. The failed ammonia Pump Module that was replaced in August 2010 was returned inside "Atlantis"'s payload bay, on the upper side of the LMC. Also, a problematic Common Cabin Air Assembly (CCAA) Heat Exchanger (HX) was expected to be returned inside the MPLM. The shuttle also brought back material, including experiments, in its middeck lockers. Since STS-135 only had four crew members, astronauts did not occupy the middeck. Resultingly, compared to previous shuttle missions to the Space Station, additional storage space was available.
Other supplies.
An iPhone was used by astronauts to log experiments, and was left on the ISS for future use. Two Nexus S smartphones were also installed inside Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) to allow the crew to pilot them aboard the ISS.
Shuttle processing.
External Tank 138 (ET-138) was produced at the Michoud Assembly Facility (MAF) in New Orleans and arrived at the Kennedy Space Center on the Pegasus barge. After offloading, the tank was transported into a checkout cell inside the VAB on July 14, 2010.
NASA initially planned for STS-134 ("Endeavour") to fly with the newer ET-138 and for the LON STS-335 ("Atlantis") mission to utilize the refurbished ET-122 only in the event that a rescue of "Endeavour"'s crew were required. During Hurricane Katrina, ET-122 was damaged at the Michoud Assembly Facility (MAF) in New Orleans and while the tank was certified as completely flight-worthy after its repairs were completed, NASA management ruled that ET-122 posed a slightly higher risk of losing foam from the repaired areas and therefore assigned it to the STS-335 mission that would likely never fly. However, once it was decided to fly "Atlantis" on a full STS-135 mission, the tank assignments were swapped so that in the event STS-134 ("Endeavour") were to suffer damage from ET-122, "Atlantis" with the newer and less risky ET-138 would be poised to rescue "Endeavour"'s crew.
In early December 2010, ground technicians installed the main engines on "Atlantis". The Shuttle received the center engine on December 7, 2010, followed by the lower-right engine and the lower-left on December 8 and 9, 2010 respectively inside Orbiter Processing Facility (OPF-1). The event marked the last set of main engines to be installed on a Space Shuttle.
Stacking operations of the Solid Rocket Boosters (SRBs) for the mission commenced in the evening hours of March 29, 2011. Technicians inside the VAB, lifted the left-aft segment from the handling crate and carefully maneuvered into High Bay No. 1 and finally onto the mobile launch platform. The booster stacking was completed in mid April. The completed boosters had a mixture of refurbished and unflown elements (11 sections on each booster). For example, the forward dome for the right-hand booster is new, while the upper cylinder on the left booster flew with STS-1 – the historic maiden flight of Space Shuttle "Columbia". (For detailed information on the STS-135 boosters, see)
After completing the assembly process, the ET-138 was mated to the SRBs on April 25.
Visit by President Obama's family.
President Barack Obama, his wife Michelle Obama, and their daughters, Malia and Sasha, viewed "Atlantis" at the Orbiter Processing Facility (OPF-1) on their visit to the Kennedy Space Center on April 29, 2011. The president's family missed the launch of "Endeavour" on the STS-134 mission, as the first launch attempt was scrubbed due to problems with two heaters on one of "Endeavour"'s auxiliary power units (APUs).
During their tour of