STS-127

Close-up view of the Ground Umbilical Carrier Plate on STS-127's external tank during the first maintenance effort

The launch countdown began June 10, 2009, but on June 13, 2009, as tanking was underway, a gaseous hydrogen leak on a vent line near the Ground Umbilical Carrier Plate was observed, and the June 13, 2009, launch was scrubbed at 00:26 EDT. As liquid hydrogen fuel is pumped in, some of it boils off as the extremely cold liquid enters the warm external tank. The vent line valve controls the resulting buildup of gas pressure by allowing excess gas to escape into a ground-side vent line, which leads to a flare stack at a safe distance away from the pad. A similar leak situation was seen during the first launch attempt of STS-119. NASA managers met on June 14, 2009, and June 15, 2009, and evaluated the leak, discussed steps that had to be taken, and set a new launch date of June 17, 2009, at 05:40 EDT.[7][8]

A second launch attempt was made on June 17, 2009, for which NASA moved the planned launch of the Lunar Reconnaissance Orbiter to a new date. On June 17, 2009, loading of the shuttle's external tank with liquid hydrogen and liquid oxygen was delayed three hours due to poor weather around the launch site, but tanking began once the weather cleared. Approximately two hours after tanking began, engineers saw leak indications in the GUCP similar to those seen during the first launch attempt. The launch was officially scrubbed at 01:55 EDT.[11]

Following the launch scrub, Chairman of NASA's Mission Management Team LeRoy Cain noted that engineers would work to understand the hydrogen leak issue and come up with a solution to the problem. Cain said managers were hopeful that the issue could be resolved in time for the next available launch opportunity on July 11, 2009.[23] Due to the delay of STS-127, managers noted that it was likely that the launch of STS-128 on August 7, 2009, would be pushed back slightly.[23]

Lightning strikes Endeavour's Launch Pad.

On July 1, 2009, the shuttle managers conducted a new series of tanking tests to confirm a hypothesis that a misaligned vent port housing was the root cause of the leaks. The existing rigid seal was replaced with a flexible one in the hope that it would maintain a tight fix even under the cryogenic conditions that seem to cause the leak. The test was declared a success with no leaks detected on the GUCP. The mission was announced to be targeting a July 11, 2009, launch.[24][25] On the evening of July 10, 2009, the launch pad region was hit by eleven strikes of lightning, which pushed back the July 11, 2009, launch time by at least 24 hours. Two of the strikes were strong enough to trigger an evaluation by NASA engineers. The inspections revealed that no damage had been done to the Space Shuttle.[NASA 9]

NASA scrubbed Endeavour' July 12, 2009, launch attempt at T-minus 9 minutes and holding due to Cumulus clouds and lightning near the launch pad. During the final Go/No-Go polls, Mission Control in Houston declared a "No-Go" due to unacceptable weather forecast for a possible Return-To-Launch-Site (RTLS) abort, and planned for emergency scenarios when one or more engines shut down early leaving insufficient energy to reach the Transatlantic Abort Landing (TAL) sites. Similarly, during the July 13, 2009, attempt, RTLS weather was also "no go." Meanwhile, shuttle weather officer Kathy Winters informed the launch director, Pete Nickolenko, that the launch pad weather had changed to RED as the Phase-1 Lightning warning was issued for the Kennedy Space Center. The launch was scrubbed at T-minus 9 minutes and holding and was quickly reset for July 15, 2009 (a 48 hours scrub turn around) due to weather concerns on July 14, 2009, and the desire to replace the Tyvek covers over the forward Reaction Control System thrusters.[NASA 10]

On July 15, 2009, at 18:03:10 EDT, the launch was finally successful.[32] Upon reviewing the launch video footage, imagery analysts noted eight or nine instances of foam shedding from the External Tank.[33] The pictures of the external tank taken when jettisoning showed loss of foam in the intertank ribbing.[34] The chairman of the Mission Management Team was not concerned and felt that the Space Shuttle would be cleared for re-entry on its return voyage—which it was a few days later.[35][36][NASA 11] The payload doors were opened after reaching orbit followed by deployment of the K_u band antenna and activation of the shuttle's mechanical arm.[37]

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  Liftoff of Space Shuttle Endeavour from Launch Pad 39A
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  Wide angle view of Endeavour lifting off the pad

Julie Payette looks through an overhead window while operating controls on the aft flight deck of Endeavour during flight day two activities.

The thermal protection system was inspected with the Shuttle Robotic Arm/Orbiter Boom Sensor System (OBSS) and the voluminous data downlinked for analysis. The orbital maneuvering system pods were inspected for tile damage or protruding tiles. The extravehicular mobility units were checked in addition to the rendezvous system tests and centerline camera installation. In preparation for the docking, the docking ring was extended.[37][NASA 12]

The shuttle successfully docked with the station 220 miles (350 km) above the Earth, following rendezvous pitch maneuver (RPM) photography of Endeavour's thermal protection system by the Expedition 20 Crew.[38] During this procedure, the shuttle flips over on its back to the station so that the station crew can capture high resolution imagery of the underside of the shuttle. The docking happened on the ISS's PMA-2 (Pressurized Mating Adapter) on the Harmony module and the hatch was opened after leak checks. As part of the crew swap, station crew member Koichi Wakata was replaced with Tim Kopra. The two astronauts specially fitted seatliners were interchanged.[NASA 13] As part of preparation for EVA 1, astronauts Wolf and Kopra camped out in the Quest airlock. A quick review of the RPM imagery showed no serious concerns beyond two instances of coating loss. Further analysis of the imagery will be done. A boost of the station was completed with the shuttle's vernier thrusters to avoid a piece of space debris. The SRBs were retrieved and their camera imagery is expected to give more detail on the ET foam shedding.[15]

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  Endeavour from ISS before docking
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  One of Endeavour's aft flight deck windows frames the nearby International Space Station.
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  Astronaut Christopher Cassidy uses a rangefinder to determine the distance to ISS before docking
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  RPM image of Endeavour as taken from ISS

EVA 1 started with astronauts Dave Wolf and Tim Kopra switching their spacesuit power to internal battery at 16:19 UTC. Despite a communication problem with the spacewalkers, the Japanese Exposed Facility was successfully installed on the Japanese Experiment Module by means of a complex series of steps involving the robotic arms of both the station and the shuttle.[NASA 14] The JEF was first unberthed from the shuttle payload bay by the station arm, after which the shuttle arm took the load. The station arm was then moved to the worksite on Node-2 (Harmony), wherefrom it took the 4.1 ton facility back. The facility was then successfully latched on to the Experiment Module.[39][40][41] As part of the EVA, the spacewalkers successfully deployed the port Unpressurized Cargo Carrier Attach System (UCCAS), which could not be deployed during STS-119. During the prior mission, the deployment failed due to a jamming caused by a stuck detent pin. Engineers designed a custom tool to force the pin to release, which was used to deploy the mechanism.[42] Meanwhile, the shuttle managers announced that there would be no need for a focused inspection of the heat shield. The nose cap and wing leading-edge panels of the shuttle were cleared for entry as they were, but a reentry clearance was not given.[NASA 14] Beyond one impact site having a gouge, the rest of the impacts were found to be mostly a loss of coating.[43] The other activity scheduled for EVA 1, the deployment of a starboard side cargo carrier, was postponed for want of time.[42] A fuel cell issue found before launch was analyzed, though the cell continued to function as expected with no impact to the mission.[39]

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  Tim Kopra working to prepare the berthing mechanisms on the Kibō laboratory and the Japanese Exposed Facility (JEF) for the JEF installation on Kibō, during space walk 1.
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  JEF in the grasp of the shuttle's robotic arm.

ICC handoff by shuttle's robotic arm

The installation of the Integrated Cargo Carrier-Vertical Light Deployable (ICC-VLD) on the port side of the station was successfully completed with the use of both the shuttle and station robotic arms. The cargo pallet, containing spares and fresh batteries for the station, was lifted out of the shuttle bay by the shuttle arm and handed off to the station's Canadarm2, which maneuvered it to its position. The pallet's contents will be set up in upcoming EVAs. A malfunction in a new toilet in the Destiny laboratory caused the crew to use the one in the Russian segment while attempts were made to identify the fault. Meanwhile, the shuttle was cleared for reentry.[NASA 15][44][45][46]

Astronauts Wolf and Marshburn began EVA 2 at 15:27 UTC out of the Quest airlock. The EVA was to transfer the spare components brought by the shuttle from the ICC-VLD to External Stowage Platform-3. The spares were handled by Wolf riding the station's robotic arm to the P3 truss stowage platform where he and Marshburn attached them for long-term storage. The purpose of the spares was to provide redundancy to the station in the period following the shuttle's retirement. The spares unloaded include a Ku-Band Space-to-Ground antenna, a pump module for the coolant system and a drive unit for the station's robotic arm's mobile transporter. A planned installation of a camera on the Japanese Experiment Facility was postponed to a future EVA for want of time. Meanwhile, the malfunctioning toilet was set right with the replacement of internal parts and cleared for normal use after tests.[NASA 16][47][48][49]

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  Dave Wolf performs his second space walk, which is also the second of five scheduled space walks for STS-127.
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  Tom Marshburn performs his first space walk, the STS-127 crew's second of the five scheduled.
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  Another view of Marshburn during his first space walk.

Japanese logistics carrier(JLE) handoff from shuttle to station.

In one of the more relaxed days, the Japanese logistics carrier was attached to the Japanese Exposed Facility. The cargo pallet was unberthed from the shuttle by the shuttle's robotic arm and handed to the station's robotic arm which then soft fixed it temporarily to the facility. After the experiments, containing an X-ray astronomy payload, a space environment monitor and a communications system, are installed the pallet will be returned to Earth by the shuttle.[NASA 17][50]

Cassidy works near the JEF during space walk 3.

The spacewalk involving astronauts Wolf and Cassidy started at 14:32 UTC. As part of preparation for experiment installation on the Japanese external science deck, Cassidy removed the thermal covers off the experiment carrier. Meanwhile, Wolf removed obstructions, consisting of a steel handrail and an equipment installation socket, from the Harmony node to clear the way for an upcoming Japanese automated resupply ship. The other task for EVA 3, involving replacement of four of the six batteries in the P6 truss, did not go as planned. Each 170 kg (375 lb) battery was to be removed and placed in a temporary stowage platform while a new one is taken from the ICC-VLD and fixed. The old ones will be returned to Earth. When two new batteries had been installed and three old ones removed, the CO₂ levels in Cassidy's suit showed an upward trend. Even though it never exceeded the safety limits, the EVA was called off with both astronauts returning into the station. This left one old battery in a temporary flexible stowage position. The rest of the batteries will be installed in a future EVA with the rest of the EVAs being under replanning.[NASA 18][51][52][53]

The Kibō robotic arm was inaugurated operationally with it being used to install experiments on to the Japanese exposed facility. The three experiments, transferred from the Japanese cargo pallet, consisted of Monitor of All-sky X-ray Image, Inter-orbit Communication System and Space Environment Data Acquisition Equipment-Attached Payload. As per the revised plan for EVA 4 astronauts Cassidy and Marshburn will replace the remaining four batteries on P6 and complete the already deferred installation of a camera on the Japanese experiment facility.[NASA 19][NASA 20][54]

The fourth spacewalk, by Cassidy and Marshburn, involved replacement of the final four of the six batteries on P6 truss integrated electronics assembly. After berthing the old batteries in the ICC-VLD, the cargo pallet was returned to the Endeavour's payload bay by the shuttle's robotic arm. The elevated levels of CO₂ in Cassidy's suit during EVA 3 was attributed to the astronaut working at a fast pace.[NASA 21][55][56]

The crew of both the shuttle and station had a day off. The day was uneventful except for the station's American CO₂ removal system shutting down without any immediate impact.[NASA 22][57][58]

The Japanese Exposed Section cargo carrier was berthed in Endeavour's payload bay by the shuttle's robotic arm after it was handed the pallet by the station's robotic arm. After this the crew of both the station and the shuttle held a joint news conference. Meanwhile, the malfunctioning American CO₂ removal system has been transitioned to manual mode in order to keep it running.[NASA 23][59][60]

Marshburn and Cassidy during space walk 5

Cassidy and Marshburn started EVA 5 at 11:33 UTC when they switched their suit power to internal battery. For this spacewalk, the CO₂ absorbent system in the suits were changed from Lithium Hydroxide to METOX due to problems with Cassidy's usage. Cassidy completed the reconfiguring of power channels in the Zenith 1 patch panel which are used for the control moment gyroscopes. Before the rewiring, two of the gyroscopes were fed by the same power channel. Since a failure of the channel can knock down two gyros and put the station in a degraded position the reconfiguration was made necessary. This rewiring made the two gyros to operate from separate power channels. Meanwhile, Marshburn secured some multi-layered insulation on the Dextre. Later both the spacewalkers installed video cameras on the front and back of the Japanese exposed facility which will be used in dockings of the Japanese cargo crafts and normal operation. The cameras flew up in launch configuration and now have been installed in an operational configuration, thus completing the JEF assembly. Meanwhile, due to Cassidy's METOX limitation, the deployment of the PAS was deferred to a future spacewalk. Instead some get ahead tasks were completed which included installation of handrails and a portable foot restraint.[NASA 24][61][62][63][64]

After a crew farewell Endeavour undocked from the ISS at 17:26 UTC. Unlike most other launches, hatch closure, which happened at 15:08 UTC, and undocking happened on the same day due to the extended delay in launching and the arrival of the Progress 34 cargo craft. After undocking Hurley began a fly around of the station giving the shuttle crew an opportunity to photograph the station's current configuration in all directions. Then a final separation burn was completed at 3:09 pm EDT.[NASA 25][65][66]

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  Endeavour shortly after the shuttle and station post-undocking separation.
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  ISS shortly after the shuttle and station post-undocking separation with the JEF prominently seen.

Image of orbital sunset taken from Endeavour one day before the shuttle landed

The OBSS was grappled by the shuttle's robotic arm and used to inspect Endeavour's thermal protection system for damage from orbital debris. The imagery will be analyzed to clear the shuttle for reentry.[NASA 26] Meanwhile, the foam loss on the external tank was initially attributed to substrate contamination ahead of the application of the foam.[67] Later during the processing of STS-128, voids in the foam was highlighted as a trigger for the shedding. The air trapped in the voids could have expanded due to the high temperatures generated during ascent thus breaking the foam.[68][69]

The crew checked out the shuttle's systems for the landing, and successfully deployed the DRAGONSat and ANDE-2 satellites. The shuttle was cleared for reentry, with the TPS imagery showing no concerns.[NASA 27][70][71] The shuttle tracked two chances of landing at KSC on July 31, and could land no later due to its limited carbon dioxide-scrubbing LiOH supply.[72]

After a 16-day mission, Endeavour landed successfully at Kennedy Space Center at 10:48 EDT on July 31, 2009. The landing had to be undertaken before August 1, due to CO₂-scrubbing lithium hydroxide limitations. There were two opportunities to land on July 31, of which the first was ultimately utilized.[NASA 28][73]

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  Endeavour touches down at Kennedy Space Center.
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  Endeavour deploys its drag chute to aid deceleration.