STS-135
STS-135 was the 135th and final mission of NASA's Space Shuttle program, launched aboard the orbiter Atlantis on July 8, 2011, from Launch Pad 39A at Kennedy Space Center in Florida.[1][2] The crew consisted of Commander Christopher J. Ferguson, Pilot Douglas G. Hurley, and Mission Specialists Sandra H. Magnus and Rex J. Walheim, who conducted a 12-day flight to the International Space Station (ISS), delivering over 9,400 pounds of supplies, spare parts, and equipment via the Raffaello multi-purpose logistics module (MPLM).[1][2] The mission also involved installing the Robotic Refueling Mission experiment and other payloads on the ISS's exterior, as well as a spacewalk to retrieve a failed ammonia pump module from the station's cooling system.[1] Atlantis docked with the ISS on July 10, enabling the transfer of approximately 5,700 pounds of return cargo and completing the final major logistics resupply flight for the Shuttle era, which had assembled and supported the station over 37 dedicated missions.[1][2] The orbiter, on its 33rd flight, traveled 5.2 million miles and orbited Earth 200 times before landing safely at Kennedy Space Center on July 21, 2011, marking the conclusion of the 30-year program that had flown 135 missions since 1981.[1][2] STS-135's success underscored the Shuttle's role in enabling sustained human presence in low Earth orbit, while transitioning NASA toward commercial crew and cargo partnerships for future ISS operations.[1]Background
Space Shuttle Program Context
The Space Shuttle Program, formally approved by President Richard Nixon on January 5, 1972, represented NASA's effort to create a partially reusable spacecraft system for cost-effective access to low Earth orbit, enabling satellite deployment, scientific research, and eventual support for space station operations.[3] Development began in the late 1960s amid post-Apollo budget constraints, emphasizing a winged orbiter that could land like an aircraft, paired with expendable external tanks and recoverable solid rocket boosters, to ferry crews and payloads of up to 55,000 pounds to orbit.[3] The program's design prioritized operational flexibility over full reusability, as the external tank was jettisoned and discarded after each launch, a compromise driven by engineering trade-offs and fiscal limitations that ultimately inflated per-mission costs beyond initial projections of $10-20 million to averages exceeding $450 million by the 2000s.[3] The first orbital test flight, STS-1, lifted off on April 12, 1981, from Kennedy Space Center's Launch Complex 39A aboard the orbiter Columbia, validating the vehicle's aerodynamic stability and systems integration with astronauts John Young and Robert Crippen at the controls.[3] Operational missions commenced with STS-5 on November 11, 1982, introducing payload deployment capabilities, and the fleet expanded to five orbiters—Columbia, Challenger, Discovery, Atlantis, and Endeavour—which collectively executed 135 flights through 2011, transporting 355 individuals to space and delivering over 3 million pounds of pressurized and unpressurized cargo.[4] Key achievements included the deployment of the Hubble Space Telescope in 1990 (STS-31), multiple servicing missions that extended its lifespan, and 37 dedicated flights that assembled and resupplied the International Space Station from 1998 onward, ferrying truss segments, solar arrays, and habitation modules essential to its completion.[4] Despite these successes, the program encountered profound setbacks that underscored vulnerabilities in its hybrid reusable-expendable architecture. The *Challenger* disaster on January 28, 1986, during STS-51-L, destroyed the orbiter 73 seconds after launch due to O-ring failure in cold temperatures, killing all seven crew members and grounding the fleet for 32 months while NASA implemented redesigns to the solid rocket boosters.[3] Operations resumed with STS-26 on September 29, 1988, but the *Columbia* accident on February 1, 2003, during STS-107 reentry—caused by foam debris breaching the orbiter's thermal protection system—claimed another seven lives and halted flights until STS-114 on July 26, 2005, following reinforced wing leading edges and launch inspections.[3] These incidents, rooted in causal factors like thermal stresses on non-reusable components and inadequate risk assessment for debris, highlighted systemic issues in balancing reusability with safety, contributing to a cumulative loss rate of two vehicles and prompting congressional scrutiny over the program's $200 billion total cost.[4] By the late 2000s, the aging orbiter fleet, with airframes exceeding 20,000 flight cycles in some cases, and persistent maintenance demands shifted program focus toward graceful retirement, paving the way for STS-135 as the capstone mission that delivered final logistics to the ISS while transitioning U.S. human spaceflight to commercial and next-generation systems.[1]Retirement Rationale and Final Mission Approval
The retirement of the Space Shuttle program stemmed from the Vision for Space Exploration, announced by President George W. Bush on January 14, 2004, which prioritized completing International Space Station assembly before phasing out the Shuttle to reallocate funds toward new initiatives, including the Crew Exploration Vehicle for missions beyond low Earth orbit, lunar exploration, and eventual Mars objectives.[5] This directive addressed the Shuttle's operational limitations, including high maintenance costs from infrequent flights—averaging fewer than five per year against an initial goal of 50—and inherent safety risks, underscored by the loss of Challenger in 1986 and Columbia in 2003, which resulted in 14 astronaut fatalities across 135 missions.[6][7] The program's design for partial reusability failed to achieve anticipated economies, with lifecycle costs exceeding $200 billion, rendering continued operation unsustainable relative to emerging alternatives.[7] STS-135 emerged as the program's capstone mission, positioned as a contingency following STS-134 to deliver additional supplies and spare parts to the ISS amid delays in the retirement timeline.[1] The Obama administration's fiscal year 2011 budget proposal initially excluded funding for STS-135, projecting savings of about $600 million to support commercial crew development and other priorities, reflecting a policy emphasis on transitioning to private-sector partnerships for low Earth orbit access.[8] Congressional action intervened through the National Aeronautics and Space Administration Authorization Act of 2010 (S. 3729), passed in September and signed into law by President Obama on October 11, 2010, which mandated NASA to conduct STS-135 using existing resources, contingent on a comprehensive flight safety review.[9][10] This legislation authorized $58.4 billion over three years for NASA programs, including space operations, overriding the proposed cancellation to ensure ISS support continuity and program closure.[11] NASA managers approved mission planning on August 20, 2010, targeting a June 28, 2011, launch, with final baselining enabled by the act.[8] The fiscal year 2011 appropriations provided $5.5 billion for space operations, facilitating preparations despite technical hurdles like external tank ET-138 production.[1] Following positive safety assessments, Atlantis launched STS-135 on July 8, 2011, marking the definitive end of the Shuttle era.[1]Funding and Political Context
Budgetary Realities and Allocations
The Space Shuttle program's persistent high operational costs, estimated at approximately $1.6 billion per flight when amortized over its 135 missions, contributed significantly to the decision to retire the fleet amid NASA's constrained federal funding, which hovered around 0.5 percent of the total U.S. budget by fiscal year 2011.[12] [13] Initial projections in the 1970s had promised reusable flights at costs as low as $20 million each, but design compromises driven by budget limits—such as partial reusability and reliance on expendable components like solid rocket boosters and external tanks—resulted in far higher expenditures, totaling nearly $209 billion through 2010 in inflation-adjusted dollars.[12] These realities underscored the program's failure to deliver economical access to orbit, prioritizing completion of the International Space Station over indefinite extension.[8] For STS-135, NASA's fiscal year 2011 budget request allocated $989.1 million to the Space Shuttle Program within the broader $5.5 billion Space Operations directorate, explicitly supporting the execution of remaining flights including the final Atlantis mission to resupply the ISS.[14] This funding covered flight hardware ($331.1 million), ground and flight operations ($373.2 million), and program integration ($284.8 million), with preparations commencing despite initial uncertainties over appropriations.[14] The Obama administration's proposal initially aimed to retire the shuttle after STS-134 to align with post-Constellation priorities, but congressional insistence—via bipartisan authorization and appropriations bills—secured the additional resources, providing over $1 billion extra beyond the baseline request to enable STS-135 and preserve workforce capabilities during transition.[15] [16] Post-mission, shuttle funding dropped to $86.1 million in FY2012 for decommissioning, reflecting the program's conclusive end.[14]Congressional Decision-Making Process
The congressional decision-making process for STS-135 began amid ongoing debates over the Space Shuttle program's retirement and the transition to commercial resupply for the International Space Station (ISS). Lawmakers expressed concerns that ending shuttle flights after STS-134 could jeopardize ISS operations if private-sector cargo capabilities, such as SpaceX's Dragon, faced delays, prompting calls for an additional logistics mission.[17] In response, the House Science and Technology Committee incorporated provisions in its compromise NASA authorization bill released in September 2010, formally authorizing STS-135 as a "launch-on-need" mission no earlier than June 1, 2011, to deliver critical supplies via the Raffaello multi-purpose logistics module.[18] This authorization gained traction through bipartisan negotiations, culminating in the NASA Authorization Act of 2010 (Public Law 111-267), signed by President Obama on October 11, 2010. The act explicitly directed NASA to conduct STS-135, subject to a safety certification review, to ensure sufficient upmass capability for the ISS amid uncertainties in commercial cargo development; it authorized up to $5.5 billion in fiscal year (FY) 2011 appropriations for space operations but did not appropriate funds itself.[10] NASA's internal planning advanced provisionally, with the mission baselined for a June 28, 2011, launch target by August 2010, though full implementation hinged on budgetary confirmation to avoid workforce disruptions at Kennedy Space Center.[8] Appropriations proved contentious due to broader FY2011 budget gridlock, leading to multiple short-term continuing resolutions (CRs) that maintained prior-year funding levels insufficient for a full shuttle mission. NASA managers proceeded with preparations under these constraints, emphasizing the mission's necessity for ISS sustainability regardless of final funding outcomes.[19] Resolution came with the Department of Defense and Full-Year Continuing Appropriations Act, 2011 (Public Law 112-10), enacted April 15, 2011, which provided $5.532 billion for NASA's Space Operations directorate—explicitly enabling STS-135 by covering the estimated $500 million cost for orbiter processing, payload integration, and launch operations through September 30, 2011.[20] This funding decision reflected congressional prioritization of operational continuity over fiscal austerity, despite the Obama administration's initial budget request omitting dedicated line-item support for the extra flight.[17]Crew
Composition and Roles
The STS-135 crew comprised four NASA astronauts: Commander Christopher J. Ferguson, Pilot Douglas G. Hurley, Mission Specialist Sandra H. Magnus, and Mission Specialist Rex J. Walheim.[2] This was the smallest crew assigned to a Space Shuttle mission since STS-6 in 1983, a reduction from the typical six or seven members due to the mission's focused objectives, cost considerations amid program retirement, and the absence of a required rescue vehicle contingency.[21] All crew members were veterans of prior shuttle flights, bringing collective experience in orbiter operations, International Space Station liaison, robotics, and extravehicular activities essential for delivering the Raffaello Multi-Purpose Logistics Module and installing payloads on the ISS.[1] Ferguson, a retired U.S. Navy captain, served as commander, holding ultimate responsibility for mission execution, crew safety, and coordination with ground control and the ISS Expedition 28 crew.[22] Hurley, a U.S. Marine Corps colonel, acted as pilot, supporting ascent and deorbit maneuvers, monitoring vehicle systems, and prepared to assume manual control for landing if required.[2] Magnus, with prior long-duration residency on the ISS during Expedition 18, functioned as a mission specialist focused on cargo transfer operations from the Raffaello module, leveraging her expertise in station logistics.[23] Walheim, an Air Force colonel experienced in spacewalks, served as the other mission specialist, primarily operating the shuttle's Canadarm2 for payload deployment and retrieval, including the Lightweight Multi-Purpose Carrier and Robotic Refueling Mission, while also supporting potential contingency EVAs.[1]Selection and Training
The STS-135 crew was formally assigned by NASA on September 14, 2010, after the mission received congressional approval via the 2010 NASA Authorization Act, transforming it from a potential contingency flight into the Space Shuttle Program's finale.[24] Commander Christopher J. Ferguson, with prior command experience on STS-115 in 2006, led the team; Pilot Douglas G. Hurley, who served as pilot on STS-127 in 2009, offered recent flight proficiency; Mission Specialist Sandra H. Magnus contributed International Space Station residency from Expedition 18/19 and STS-126 in 2008; and Mission Specialist Rex J. Walheim provided extensive extravehicular activity expertise from STS-110 (2002), STS-119 (2009), and STS-122 (2008).[25] This four-person complement, the smallest since STS-6 in 1983, was chosen for their proven skills in orbiter operations, docking, payload handling, and contingency planning, aligning with the mission's focus on resupply via the Raffaello module and Lightweight Multi-Purpose Carrier installation.[2] Training spanned roughly 10 months, integrating standard astronaut protocols with mission-specific preparations at NASA's Johnson Space Center and Kennedy Space Center. The crew conducted numerous integrated simulations replicating orbital rendezvous, docking to the ISS, and transfer operations, including robotics drills for the Shuttle Remote Manipulator System to deploy and capture payloads.[2] Walheim and Magnus rehearsed potential spacewalks in the Neutral Buoyancy Laboratory, despite none being scheduled, to maintain proficiency in suited operations and equipment manipulation. Payload familiarization involved hands-on sessions with the Raffaello Multi-Purpose Logistics Module's racks and the Lightweight Multi-Purpose Carrier's components, such as the Robotic Refueling Mission and Materials Science experiments, at the Space Station Processing Facility.[26] Emergency procedures training emphasized launch pad safety, with the crew practicing evacuation routes and driving the M113 Armored Personnel Carrier at Kennedy Space Center on June 21, 2011.[27] Flight skills were honed through T-38 jet proficiency flights and touch-and-go landings in the Shuttle Training Aircraft; on July 5, 2011, Ferguson and Hurley executed such maneuvers over the Kennedy Space Center Shuttle Landing Facility to refine reentry and landing techniques.[28] The team also prepared for Soyuz contingency via fittings for Russian Sokol suits and Soyuz seat liners, reflecting program-end uncertainties. In June 2011, the crew participated in the Terminal Countdown Demonstration Test, a full-scale rehearsal of launch-day activities, including suit-up, walkout, and countdown integration, arriving at Kennedy Space Center on June 20 aboard T-38 aircraft.[2]Mission Parameters
Primary Objectives
The primary objectives of STS-135 centered on resupplying the International Space Station (ISS) with essential equipment and spares to extend its operational life post-Shuttle retirement. Atlantis carried the Raffaello Multi-Purpose Logistics Module (MPLM), loaded with approximately 8,000 pounds (3,600 kg) of supplies, including food, clothing, and maintenance parts, to support ISS crews for up to 18 months without further Shuttle deliveries.[3] The module was transferred to the ISS during docked operations, with cargo unpacked and refuse returned in Raffaello for disposal upon undocking.[1] A key objective involved installing the Lightweight Multi-Purpose Carrier (LMC) on the ISS's ExPRESS Logistics Carrier-4 (ELC-4) via robotic arms, carrying the Robotic Refueling Mission (RRM) payload to test satellite servicing technologies. RRM demonstrated remote refueling of cryogenic propellants and tool operations using the Special Purpose Dexterous Manipulator (SPDM), aiming to validate methods for extending satellite lifespans without human intervention.[29] [30] The LMC also housed other experiments, such as the Materials Science Research Rack and sensor tests, enhancing future space technology development.[1] Crew members further retrieved a failed Pump Module from the ISS's External Thermal Control System for return to Earth, enabling ground analysis to prevent similar failures and inform ammonia reservoir designs.[21] Secondary goals included deploying the PicoSat Solar Cell experiment picosatellite to study space environment effects on photovoltaic cells, though these supported broader ISS logistics and research continuity rather than core mission mandates.[1]Flight Profile and Technical Details
STS-135 launched on July 8, 2011, at 11:29 a.m. EDT (15:29 UTC) from Launch Complex 39A at NASA's Kennedy Space Center, Florida, aboard the Space Shuttle Atlantis (OV-104). The mission followed a standard ISS rendezvous profile, involving ascent to low Earth orbit, a series of orbital maneuvers over approximately two days to phase with the station, automated and manual rendezvous operations, docking, and subsequent undocking after 11 days at the ISS. The total mission duration was 12 days, 18 hours, 28 minutes, and 50 seconds, culminating in a nighttime landing on July 21, 2011, at 5:56 a.m. EDT on Runway 15 at the Kennedy Space Center's Shuttle Landing Facility.[2][1] The ascent trajectory utilized the shuttle's three Space Shuttle Main Engines (SSMEs)—serial numbers 2047, 2060, and 2045—throttled to 104% at liftoff, paired with twin Solid Rocket Boosters (SRBs, configuration BI-146) providing initial thrust of approximately 3.3 million pounds each at sea level, and the External Tank ET-138, the final Super Light Weight Tank variant constructed from aluminum-lithium alloy, loaded with 1,668,500 pounds of cryogenic propellants. SRB separation occurred at about 2 minutes mission elapsed time (MET), after which the SSMEs continued firing until main engine cutoff (MECO) at roughly 8.5 minutes MET, inserting Atlantis into an initial orbit of approximately 122 nautical miles altitude and 51.6-degree inclination, aligned with the ISS orbital plane. Subsequent Orbital Maneuvering System (OMS) burns raised the apogee for rendezvous phasing, targeting a co-orbital altitude of around 220 statute miles (approximately 191 nautical miles).[31][2] Key ascent performance data included rapid altitude gains: reaching 17 km at 1.2 minutes MET, 61 km at 2.5 minutes, and stabilizing near 108 km by 5.1 minutes before MECO, with downrange distances progressing from 10 km at 1.2 minutes to over 2,000 km by orbit insertion. Rendezvous sequence initiated on flight day 2 with the first OMS-2 burn, followed by non-propulsive rolls and burns (e.g., rendezvous phasing burn) to close the gap to the ISS at about 50,000 feet behind and below. Docking occurred on July 10 at 11:07 a.m. EDT (15:07 UTC) to the Pressurized Mating Adapter-2, with relative approach speed under 0.1 ft/sec and tolerances of ±3 inches. Undocking on July 19 involved separation burns to a safe distance, enabling payload deployments and reentry preparations.[31][2] Reentry employed a steep deorbit burn using the OMS engines, targeting a ground-relative speed of about 399 km/h at touchdown, with a rollout of 2,960 meters; no significant anomalies were reported in ascent or orbital parameters, confirming nominal performance for the program's concluding flight.[1]Pre-Launch Preparation
Orbiter Processing and Modifications
Space shuttle Atlantis entered processing for STS-135 immediately following its landing on May 26, 2010, at the end of mission STS-132, when it was towed into Orbiter Processing Facility Bay 1 at NASA's Kennedy Space Center. Processing encompassed post-flight safing, comprehensive inspections of the thermal protection system including repair of any tile damage or reinforced carbon-carbon wear from reentry, and functional verification of propulsion elements such as the three space shuttle main engines, orbital maneuvering system pods, and reaction control system thrusters. Avionics systems underwent software updates and diagnostic testing to ensure compatibility with the mission profile, while the payload bay was prepared for integration of the Raffaello multi-purpose logistics module and Lightweight Multi-Purpose Carrier.[32] No major structural modifications were performed on Atlantis for STS-135, as the orbiter utilized its existing configuration validated across 32 prior flights and leveraged hardware pre-processed for the contingency STS-335 mission; efforts focused on maintenance and reliability enhancements rather than new upgrades.[33] On April 29, 2011, during ongoing operations, President Barack Obama, First Lady Michelle Obama, and their daughters toured OPF-1 and observed Atlantis suspended in its processing cradle. Processing culminated with the final closure of the payload bay doors inside an OPF, delayed slightly to accommodate additional pre-rollover tasks.[34] On May 17, 2011, Atlantis rolled out of OPF-1 to the Vehicle Assembly Building, marking the last such transfer for a flight-ready orbiter and initiating stack-up with external tank ET-138 and the solid rocket boosters already in place. This phase included tanking verification tests post-mating to confirm fuel loading and cryogenic systems integrity before rollout to Launch Pad 39A on June 8, 2011.[35][32]Payload Integration and Verification
The primary payloads for STS-135, the Raffaello Multi-Purpose Logistics Module (MPLM) and Lightweight Multi-Purpose Carrier (LMC), underwent processing, integration, and verification at NASA's Kennedy Space Center (KSC) under the Checkout, Assembly and Payload Processing Services (CAPPS) contract managed by Boeing.[22] The Raffaello MPLM, loaded with approximately 8,640 pounds (3,920 kg) of supplies including eight Resupply Stowage Platforms, two Intermediate Stowage Platforms, and six Resupply Stowage Racks, had cargo installation beginning on April 11, 2011, in the Space Station Processing Facility (SSPF).[36] By mid-June 2011, the module was fully packed and prepared for shuttle integration.[37] Integration of the Raffaello MPLM into Atlantis's payload bay occurred in the SSPF or adjacent facilities, followed by mating to the orbiter prior to the stack-up with the external tank and solid rocket boosters.[22] The LMC, weighing 946 pounds (429 kg) empty and carrying the Robotic Refueling Mission (RRM) hardware on ascent, was assembled and tested at KSC, featuring a custom adapter plate for the failed External Thermal Control System (ETCS) Pump Module retrieval.[22] It was mounted adjacent to the MPLM in the payload bay, with total launch weight for the LMC configuration reaching 2,918 pounds (1,324 kg).[21] Verification processes included structural integrity checks, functional testing of experiments like RRM components, and compatibility assessments with shuttle and ISS interfaces conducted pre-launch at KSC.[22] Payload elements were subjected to environmental simulations and electrical verifications to ensure readiness.[38] The final integrated payload was delivered to Launch Pad 39A on June 18, 2011, after completing all ground-based inspections and certifications.[39] Secondary payloads, such as student experiments, were integrated closer to launch, around July 1, 2011, with handover to NASA for final shuttle mating.[40] These steps confirmed the payloads' operational reliability for the mission's logistics delivery and technology demonstration objectives.[22]Launch Sequence
Countdown Events and Delays
The countdown for STS-135 began at 12:00 p.m. EDT on July 5, 2011, initiating a three-day terminal countdown sequence targeting a launch window opening at 11:29 a.m. EDT on July 8 from Launch Complex 39A at Kennedy Space Center.[41] This followed Atlantis's rollout to the pad on June 30 and included standard pre-countdown processing such as payload bay door checks, hypergolic fuel loading for the Orbital Maneuvering System (OMS) pods, and final verifications of the External Tank ET-138 and Solid Rocket Boosters.[42] Key planned holds occurred during the countdown, including a standard pause at T-minus 11 hours on July 8 morning, resuming at 7:01 p.m. EDT the previous evening to accommodate crew ingress and final systems polls. Tanking operations for the External Tank commenced on schedule at approximately 2:01 a.m. EDT on launch day, loading liquid hydrogen and liquid oxygen without initial issues, though a brief anomaly arose when the left OMS fuel tank vent valve opened unexpectedly due to a nominal pressure trigger in the ground support equipment; this was assessed as non-critical and required no corrective action.[43] [42] A minor delay during tanking involved a bearing failure in the primary liquid oxygen (LOX) pump on the ground umbilical carrier plate, prompting a switch to the redundant pump; the issue was resolved in 21 minutes, imposing no launch constraints. Weather conditions, which had violated launch criteria earlier in the countdown due to anvil clouds and upper-level winds, improved sufficiently by T-minus 9 minutes, allowing the hold to be lifted after go/no-go polls confirmed favorable trends.[42] The most notable unplanned hold occurred at T-minus 31 seconds, when instrumentation failed to indicate proper retraction of the gaseous oxygen (GOX) vent arm—also known as the "beanie cap"—on the launch tower, halting the automated sequence start and handover to onboard computers. Launch controllers visually confirmed arm clearance and system safety, resolving the indication anomaly without physical intervention; the countdown resumed approximately 45 seconds later, still within the tight five-minute launch window that accounted for orbital rendezvous constraints.[29] [44] [42] No further holds or scrubs ensued, enabling Atlantis to lift off successfully at 11:29:04 a.m. EDT.[29]Liftoff and Ascent Trajectory
Space Shuttle Atlantis lifted off on July 8, 2011, at 11:29:00 a.m. EDT (15:29:03.996 UTC) from Launch Pad 39A at NASA's Kennedy Space Center, marking the final launch of the Space Shuttle program.[29][44] The ascent proceeded nominally, with the Solid Rocket Boosters (SRBs), Main Propulsion System (MPS), and Space Shuttle Main Engines (SSMEs) performing as designed, achieving a peak lateral acceleration of 0.12 g at liftoff.[44] Key ascent milestones included SRB separation at 2 minutes and 13 seconds mission elapsed time (MET), followed by Main Engine Cutoff (MECO) at 8 minutes and 24 seconds MET, and External Tank (ET) separation 21 seconds later.[44] The Orbital Maneuvering System (OMS) burn, designated OMS-2, occurred at 37 minutes and 45 seconds MET for 64.8 seconds to circularize the orbit.[44] Minor anomalies, such as erratic Backup Flight System (BFS) quantities and Flight Engineer Subsystem (FES) outlet temperature oscillations, were noted but resolved without mission impact.[44] The trajectory followed a standard profile for International Space Station rendezvous, targeting a 51.6-degree inclination low Earth orbit. Altitude increased rapidly post-liftoff, reaching 67 km at 2.7 minutes and 108 km by 9 minutes, while downrange distance progressed to 104 km at SRB separation and over 2,000 km by orbital insertion.[31] Between 8 and 9 minutes MET, the vehicle covered approximately 532 km at an average speed of 532 km/min (about 19,790 mph), demonstrating efficient energy addition from the SSMEs during the final ascent phase.[31] Payload bay doors were opened at 1 hour, 34 minutes, and 16 seconds MET to initiate thermal conditioning.[44]| Time (min MET) | Altitude (km) | Downrange (km) |
|---|---|---|
| 0.0 | 0 | 0 |
| 2.5 | 61 | 80 |
| 2.7 | 67 | 104 |
| 5.1 | 107 | 413 |
| 8.0 | 103 | 1,474 |
| 9.0 | 108 | 2,006 |