NASA - National Aeronautics and Space Administration

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Friction stir weld tool. (NASA/MSFC/David Higginbotham)

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> Medium (516 x 344, 72 ppi)
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External fuel tank ET-129 (Lockheed Martin)

> Large (3504 x 2336, 240 ppi)
> Medium (516 x 344, 72 ppi)
> Small (100 x 75, 72 ppi)

External fuel tank ET-129 (Lockheed Martin)

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> Medium (516 x 769, 72 ppi)
> Small (100 x 75, 72 ppi)

External fuel tank ET-129 (Lockheed Martin)

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> Medium (516 x 294, 72 ppi)
> Small (100 x 75, 72 ppi)

External fuel tank ET-129 (Lockheed Martin)

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External tank ET-127 for space shuttle Atlantis' STS-125 mission to the Hubble Space Telescope was moved into the Vehicle Assembly Building at Kennedy Space Center, Fla., July 15. Inside the building, the tank will be raised to the vertical, position, lifted and moved into a checkout cell. ET-127 is scheduled to be mated with the solid rocket boosters Aug. 7. (NASA)

+ Large (3412 x 2334, 300 ppi)
+ Medium (516 x 353, 72 ppi)
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External Tank ET-128 rolls toward a covered barge on its transporter, with the Freedom Star vessel in the background. The Freedom Star tows the transportation barge that will deliver the external tank from NASA's Michoud Assembly Facility in New Orleans to Kennedy Space Center on Florida's east coast. The five-day sea journey will take the tank from the Mississippi River-Gulf of Mexico Outlet to Florida's Banana River, which flows into the Atlantic Ocean. (Lockheed Martin/NASA Michoud)

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Chad Bryant, left, External Tank Project engineer at NASA's Marshall Space Flight Center in Huntsville, Ala., and Greg Vinyard of Lockheed Martin, prepare to install External Tank ET-125's feed through connector in a pressure vessel at the Marshall Center's Test Stand 300. The engine cutoff sensor connector is undergoing intensive testing to determine if it was the cause of false sensors readings during two space shuttle launch attempts in December at the Kennedy Space Center, Fla. (NASA/MSFC)

+ Large (1050 x 1070, 300 ppi)
+ Medium (516 x 526, 72 ppi)
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Components of space shuttle external tank ET-125's engine cut-off sensor system feed-through assembly arrived at the Marshall Center Dec. 31, 2007, where the Engineering Directorate Materials and Processes Laboratory are taking samples for failure analysis. James Perkins is pictured searching for contamination in the portion of the connector assembly that was disconnected from its mating plug, which remains in the external tank on the launch pad at the Kennedy Space Center, Fla. Perkin's test revealed no contamination in the components. Testing will continue at Marshall through Jan. 11 as part of a long-term solution to the sensor system issue.

The launch of shuttle Atlantis was postponed on Dec. 6 and Dec. 9 because of the engine cut-off sensor. Instrumentation installed during a tanking test on Dec. 18 indicated that one or more intermittent open circuits in the area of the feed- through connector on the external tank’s liquid hydrogen tank. The external parts of ET-125's connector are being replaced with others that have been soldered to ensure pin-to-socket connectivity and allow continuous electrical flow from sensors inside the external tank to the shuttle's computers.

A new target launch date has not been set for the launch of Atlantis on the STS-122 mission while the Space Shuttle Program assesses the work under way on the sensor system. (NASA/MSFC)

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+ Medium (516 x 381, 72 ppi)
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Illustration of feed-through electrical connections at the external tank liquid hydrogen tank structural interface, near the aft end of the tank. (NASA/MSFC)

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Four engine cut-off (ECO) sensors are mounted on a single, shock isolated carrier plate approximately four feet from the bottom of the liquid hydrogen tank. (NASA/MSFC)

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Overall Schematic of Engine Cutoff (ECO) and Liquid Level (Point) Sensors (NASA/MSFC)

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Space shuttle Discovery, on Launch Pad 39A at the Kennedy Space Center, Fla., where preparations continue for the targeted launch date of Sept. 30. During the STS-120 mission, shuttle crew members will deliver and install the Italian-built U.S. Node 2, Harmony, a pressurized module that will be an internal connecting port and passageway to additional international science labs and cargo spacecraft. (NASA/KSC)

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Shuttle Discovery is lowered for mating with the external tank and solid rocket boosters for the STS-120 mission, targeted to launch Oct. 23. (NASA/KSC)

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+ Medium (516 x 344, 72 ppi)
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External tank ET-125 began its five-day sea journey from NASA's Michoud Assembly Facility in New Orleans Sept. 9, headed for the Kennedy Space Center, Fla. ET-125 is scheduled to fly with Discovery on the STS-122 mission, targeted to launch in December from the Kennedy Center. (Lockheed Martin/NASA Michoud)

+ Large (2008 x 3000, 300 ppi)
+ Medium (516 x 771, 72 ppi)
+ Small (100 x 75, 72 ppi)

External tank ET-120 was lifted out of the checkout cell in the Vehicle Assembly Building at NASA's Kennedy Space Center, Fla., and attached to the twin solid rocket boosters Sept. 5. The external tank-solid rocket booster stack will next be attached to the orbiter Discovery. STS-120 is targeted to launch Oct. 23 on a 13-day mission to the International Space Station. (Lockheed Martin/NASA Michoud)

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External Tank Liquid Oxygen Feedline Bracket - The liquid oxygen feedline is attached to the space shuttle external tank with five brackets that resemble an L-shaped boomerang. The brackets allow for movement or "articulation" of the feedline to compensate for propellant flow during fueling on the launch pad, during subsequent detanking in flight and to compensate for thermal expansion and contraction of the external tank. The current design is aluminum. Brackets are primed, super light weight ablator, or SLA, is applied with a mold and the brackets are machined. The final step is the application of an approximately one-inch layer of sprayed BX-250 foam.
Beginning with Discovery's STS-124 mission in 2008, new redesigned titanium feedline brackets will fly on ET-128. Titanium is 17 times less thermally conductive than aluminum, meaning titanium does not conduct cold (or heat) as well. Thus, the tank will require less thermal protection system material. The amount of foam required for insulation on the tank will thereby be reduced. (NASA)

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Space shuttle external tank ET-120 was shipped by barge from NASA's Michoud Assembly Facility in New Orleans to the Kennedy Space Center, Fla. -- an 850-mile journey. The tank departed the Michoud harbor July 24 and is expected to arrive in Florida July 29. ET-120 is slated to fly on the STS-120 mission, targeted for October 2007. (Lockheed Martin/NASA Michoud)

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A graphic representation showing the location and type of repairs performed on External Tank, ET-124, damaged by hail when a thunderstorm passed over the Kennedy Space Center, Fla., launch pad on Feb. 26. About 1,000 damage sites, shown in blue, were repaired by removing damaged foam and reapplying specialized pour foam. About 900 sites, shown in yellow, were shallow enough to be repaired using the "sand and blend" technique. Spray repairs were performed to avoid numerous individual repairs in areas where there was a high density of damage. in areas indicated by arrows Sprayed areas are are. Repairs, which delayed launch of the STS-117 mission from March 15 to June, were performed inside the Vehicle Assembly Building at the Kennedy Center. (NASA)

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Space Shuttle Atlantis, mounted on a mobile launch platform, nears Launch Pad 39A at NASA's Kennedy Space Center, atop a crawler transporter May 15. The launch of Atlantis on mission STS-117 is targeted for June 8. (NASA/KSC)

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Lockheed Martin and NASA personnel at NASA’s Michoud Assembly Facility in New Orleans were on hand as external tank ET-117 rolled out April 2 to be loaded onto its seagoing transport for shipment to the Kennedy Space Center, Fla. The tank is expected to arrive at Port Canaveral, Fla., April 6. ET-117 is scheduled to fly on the STS-118 mission later this year, but could possibly be substituted for ET-124 on the next shuttle mission, STS-117. (NASA/Michoud Assembly Facility)

+ Large (3000 x 2008, 300 ppi)
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Space Shuttle Atlantis rolled out of the Vehicle Assembly Building at the Kennedy Space Center, Fla., on Thursday, Feb. 15, for its 3.4 mile journey to Launch Pad 39A. Resting atop the crawler transporter and traveling just under 1 mph, Atlantis made its approximately six-hour trip to the pad, arriving at 2:09 p.m. CST. The flight of Atlantis to the International Space Station is targeted for March 15. The STS-117 crew will install a new truss segment, retract a set of solar arrays and unfold a new set on the starboard side of the station. Lessons learned from two previous shuttle missions will provide the astronauts with new techniques and tools to perform their duties. The launch of STS-117 will be the first liftoff from Pad 39A in four years. (KSC)

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Space Shuttle Atlantis, on top of its transporter, rolls toward the door of the Vehicle Assembly Building at NASA's Kennedy Space Center, Fla., on Wednesday, Feb. 7. Inside, Atlantis will be lifted into high bay 1 and mated with the external tank and solid rocket boosters which are already in place on the mobile launcher platform. The rollover signals the beginning of a journey to the launch pad for liftoff on mission STS-117, targeted for March 15. The mission is the 21st to the International Space Station and will deliver a new truss segment, unfurl new solar arrays and fold up an old one – a continuation of work on the space station begun during the two previous shuttle missions. (KSC)

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External tank ET-124 is lowered between the twin solid rocket boosters in high bay 1 of the Vehicle Assembly Building at the Kennedy Space Center, Fla. The tank was mated with the boosters, already in place on the mobile launcher platform, on Jan. 19. Space Shuttle Atlantis is targeted to launch March 16 for its STS-117 mission to the International Space Station. (KSC)

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Space Shuttle Discovery nears touchdown on an illuminated Runway 15 at NASA Kennedy Space Center's Shuttle Landing Facility as the sun sets on the shortest day of the year, concluding mission STS-116. Aboard are Commander Mark Polansky, Pilot William Oefelein, and Mission Specialists Robert Curbeam, Joan Higginbotham, Nicholas Patrick and Christer Fuglesang, who represents the European Space Agency, as well as Thomas Reiter, who is returning from a 6-month stay on the International Space Station. (NASA/KSC)

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Space Shuttle Discovery arrived at launch pad 39B at NASA’s Kennedy Space Center, Fla., Nov. 9, perched atop the mobile launcher platform and carried by the massive crawler transporter. The shuttle assembly travels about one mile per hour on its 4.2-mile journey to the launch pad. The launch window for the STS-116 mission to the International Space Station opens Dec. 7. (NASA/KSC)

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Space Shuttle Discovery was moved into the Vehicle Assembly Building at the Kennedy Space Center, Fla., on Oct. 31, where it will be mated to its external tank, ET-123, and twin solid rocket boosters. Discovery is scheduled to roll to Launch Pad 39B no earlier than Nov. 7. The launch window for mission STS-116 opens Dec. 7. (NASA/KSC)

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On June 5, Lockheed Martin and NASA personnel at NASA’s Michoud Assembly Facility in New Orleans prepare the space shuttle external tank designated ET-118 for its journey to NASA’s Kennedy Space Center, Fla. The tank, seen here being transported to its seagoing carrier, left the port of New Orleans at 11:15 a.m. CDT on June 5. Carried by NASA’s transport vessel Liberty Star, ET-118 is expected to arrive June 9 at Port Canaveral, Fla. It will be mated in coming months with Space Shuttle Atlantis for the STS-115 mission, scheduled for August 2006. (NASA/Michoud Assembly Facility)

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Lockheed Martin and NASA personnel at NASA’s Michoud Assembly Facility in New Orleans load the space shuttle external tank designated ET-118 onto its seagoing transport, the NASA ship Liberty Star. The tank left the port of New Orleans at 11:15 a.m. CDT on June 5, and is expected to arrive June 9 at Port Canaveral, Fla. It will be mated in coming months with Space Shuttle Atlantis for the STS-115 mission, scheduled for August 2006. (NASA/Michoud Assembly Facility)

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Space shuttle external tank ET-119 rolls out at NASA's Michoud Assembly Facility near New Orleans to begin its four-to-five-day sea journey to NASA's Kennedy Space Center, Fla. ET-119 will help launch Space Shuttle Discovery on its next mission, STS-121. NASA managers are targeting a May launch window. (Lockheed Martin)

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Space shuttle external tank ET-119 rolls out at NASA's Michoud Assembly Facility near New Orleans to begin its four-to-five-day sea journey to NASA's Kennedy Space Center, Fla. ET-119 will help launch Space Shuttle Discovery on its next mission, STS-121. NASA managers are targeting a May launch window. (Lockheed Martin)

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Six astronauts of the STS-121 mission stand in front of External Tank-119 that will help launch Discovery on the next shuttle mission. (Lockheed Martin)

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Discovery's external tank, ET-119, rolls from the dock to the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. (NASA/KSC)

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The External Tank - 154 feet in length with a diameter of 27.5 feet—is the largest single piece of the Space Shuttle. During launch the External Tank also acts as a backbone for the Orbiter and Solid Rocket Boosters to which it is attached. In separate pressurized tank sections inside, the External Tank holds the liquid hydrogen fuel and liquid oxygen oxidizer for the Shuttle’s three Main Engines. During launch the External Tank feeds the fuel under pressure through 17-inch-wide lines which then branch off into smaller lines that feed directly into the Main Engines. Some 64,000 gallons of fuel are consumed by the Main Engines each minute. Machined from aluminum alloys, the Space Shuttle’s External Tank is the only part of the launch vehicle that is not reused. After its 526,000 gallons of propellants are consumed during the first eight and one-half minutes of flight, it is jettisoned from the Orbiter and breaks up in the upper atmosphere, its pieces falling into remote ocean waters. (Lockheed Martin)


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A heater has been added by NASA engineers to the topmost bellows on the Space Shuttle External Tank's liquid oxygen feedline to further reduce the amount of ice and frost formed prior to launch of the Shuttle. The heater is a copper-nickel alloy metal strip heater, similar to heaters used on the Solid Rocket Motor joints, designed to keep the bellows area slightly warmer than freezing -- about 40 degrees Fahrenheit. The heater strips are about 53 inches long -- the circumference of the bellows -- and about 0.5 inches wide. The heater was added after new information from debris studies performed by the Space Shuttle Engineering and Integration Office showed that ice forming on the bellows poses a significant debris concern for the Shuttle. (Lockheed Martin/NASA Michoud)


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Solid Rocket Booster bolt catcher cutaway diagram (United Space Alliance)


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Each Space Shuttle flies with two bolt catchers fixed to the forward, or top, area of the External Tank at the Solid Rocket Booster/External Tank forward attach point. Though the bolt catcher is mounted on the External Tank, it is considered part of the Solid Rocket Booster element design. (United Space Alliance)

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The original configuration of the thermal protection on the External Tank's Liquid Oxygen Feedline Bellows was angled which allowed condensate, or water, to contact the feedline rain-shield and freeze. The cold surface is caused by the minus-297 degree liquid oxygen in the feedline. (Lockheed Martin/NASA Michoud)

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The new design for thermal protection on the External Tank's Liquid Oxygen Feedline Bellows is reshaped to include a “drip-lip” that allows condensate, or water, to run off. The new "lip" is squared at its bottom end -- at a slight, 10 degree angle -- so the condensate drips off the feedline rain-shield. (Lockheed Martin/NASA Michoud)

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In the Vehicle Assembly Building, Lead Technician Todd Reeves, with United Space Alliance, attaches one of two bolt catchers on orbiter Discovery’s External Tank. At approximately two minutes into launch, Solid Rocket Booster separation begins when pyrotechnic devices fire to break the 25-inch, 62-pound steel bolts that attach the boosters to the tank. (NASA/KSC)

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The Space Shuttle's new bolt catcher housing is made from a single piece of aluminum forging, eliminating the weld from the original design. In addition, the wall thickness on the catcher has been increased from .125 to .25 inches and is made with a stronger aluminum alloy, AL7050. The bolt catcher captures part of the bolt that attaches the Solid Rocket Boosters to the Shuttle’s External Tank. (NASA/KSC)

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ET-121 rolls out at the Michoud Assembly Facility. (Lockheed Martin/NASA Michoud)

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ET-121 heads to the barge for shipment to Kennedy Space Center. (Lockheed Martin/NASA Michoud)

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+ Return to Flight External Tank Animation

Artist concept of the modified External Tank which will fly during STS-114, the Space Shuttle's Return to Flight mission. (Lockheed Martin/NASA Michoud)

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Close-up view of the redesigned bipod fitting as it is being installed on External Tank-120. (Lockheed Martin/NASA Michoud)

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The redesigned liquid oxygen (LOX) feedline bellows will fly on STS-114, the Space Shuttle's Return to Flight mission. (Lockheed Martin/NASA Michoud)

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The Protuberance Air Load Ramp, or PAL ramp, is on External Tank 120. (Lockheed Martin/NASA Michoud)

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External Tank 120 is loaded onto its covered barge at Michoud Assembly Facility in New Orleans on Dec. 31, 2004. (Lockheed Martin/NASA Michoud)

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External Tank 120 rolls out at Michoud Assembly Facility in New Orleans on Dec. 31, 2004. (Lockheed Martin/NASA Michoud)

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External Tank 120 rolls out at Michoud Assembly Facility in New Orleans on Dec. 31, 2004. (Lockheed Martin/NASA Michoud)

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External Tank 120 rolls out at Michoud Assembly Facility in New Orleans on Dec. 31, 2004. (Lockheed Martin/NASA Michoud)

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The STS-114 crew is shown with ET-120. (Lockheed Martin/NASA Michoud)

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External Tank 120 easily makes the short trip to the Vertical Assembly Building at Michoud Assembly Facility. (Lockheed Martin/NASA Michoud)

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External Tank 120 prepares to enter Cell A of the Vertical Assembly Building at Michoud Assembly Facility. (Lockheed Martin/NASA Michoud)

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Workers at the Michoud Assembly Facility raise External Tank 120 from horizontal to vertical. (Lockheed Martin/NASA Michoud)

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Workers guide External Tank 120 into the Vertical Assembly Building at Michoud Assembly Facility. (Lockheed Martin/NASA Michoud)

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The STS-114 crew, the next crew slated for flight on the Space Shuttle, examines the work being done on the External Tank's intertank flange area. (Lockheed Martin/NASA Michoud)

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The Protuberance Air Load Ramp, or PAL ramp, is one of the focus areas for the External Tank Return to Flight efforts. (Lockheed Martin/NASA Michoud)
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The External Tank's bipod area is being readied for the bipod fitting. (Lockheed Martin/NASA Michoud)

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Illustration shows the External Tank's bipod fittings -- covered by foam ramps -- as flown on the Space Shuttle Columbia. (Lockheed Martin/NASA Michoud)
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Illustration shows the External Tank's bipod fitting as it will fly when the Space Shuttle returns to flight. (Lockheed Martin/NASA Michoud)

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When the Space Shuttle returns to flight, the External Tank bipod fitting will be exposed, without a bipod foam ramp. (Lockheed Martin/NASA Michoud)
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The Liquid Oxygen Feedline Bellows is one of the focus areas for the External Tank Return to Flight. (Lockheed Martin/NASA Michoud)

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ET-120 is shown in the modification center at the Michoud Assembly Facility. (Lockheed Martin/NASA Michoud)

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The redesigned Liquid Oxygen feedline bellows, shown here, has a new "drip lip" on its cover that allows condensate to run off, thus reducing the potential for ice buildup. (Lockheed Martin/NASA Michoud)

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New processes are being used to apply foam on the External Tank's intertank flange area. (Lockheed Martin/NASA Michoud)

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Technicians ready a panel for testing foam loss on the External Tank's intertank tank. (Lockheed Martin/NASA Michoud)

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The External Tank's in-flight imaging system is being attached to ET 120. (Lockheed Martin/NASA Michoud)

+ Medium (720 x 540, 72 ppi)
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An artist's concept of the space shuttle's external tank without the Protuberance Air Load Ramps, also known as PAL Ramps. STS-121 is the first space shuttle launch to fly without these ramps on the external tank. Previously, the ramps were manually sprayed wedge-shaped layers of foam along the pressurization lines and cable running along the side of the tank. They were originally designed as a safety precaution to protect the lines and cable tray from airflow that could travel beneath them during the space shuttle's ascent. (NASA)

+ Medium (720 x 540, 72 ppi)
+ Small (100 x 75, 72 ppi)

An artist's concept of the Protuberance Air Load Ramps, also known as PAL Ramps, running alongside the pressurization lines and cable tray attached to the space shuttle's external fuel tank. STS-121 is the first space shuttle mission to fly without these ramps on the external tank. The two ramps were wedge-shaped layers of foam manually sprayed on the tank next to the lines and cable tray. They were originally designed as a safety precaution to protect the lines and cable tray from airflow that could travel beneath them during the space shuttle's ascent. (NASA)

+ Medium (720 x 556, 72 ppi)
+ Small (100 x 75, 72 ppi)

The space shuttle's external tank uses metal support brackets to attach the pressurization lines to the tank. The brackets are protected from the ice and frost that can form on the outside of the tank before and during launch by 34 foam segments called ice/frost ramps (inset). (NASA)

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The space shuttle's external tank uses metal support brackets to attach the pressurization lines to the tank. The brackets are covered with foam ramps to protect them from the ice and frost that can form on the tank before and during the launch. (NASA)

+ Medium (720 x 634, 72 ppi)
+ Small (100 x 75, 72 ppi)

This computer-generated image shows a cable tray, left, and two pressurization lines separated from the surface of the space shuttle's external fuel tank by an ice-frost ramp. The foam ramps protect the cables and metal bracket surrounding the two pressurization lines from the ice and frost that can form on the outside surface of the tank just before and during launch. (NASA)

+ Large (3072 x 2048, 72 ppi)
+ Medium (720 x 480, 72 ppi)
+ Small (100 x 75, 72 ppi)

External tank 119 rolls out of the final assembly building at NASA's Michoud Assembly Facility in New Orleans on its way to the Kennedy Space Center in Florida to be mated with the solid rocket boosters and Space Shuttle Discovery for the STS-121 mission. The space shuttle's external tank was returned to the Michoud facility for safety modifications including removal of the Protuberance Air Load, or PAL, Ramps. (NASA)

+ Large (2660 x 2128, 72 ppi)
+ Medium (720 x 576, 72 ppi)
+ Small (100 x 75, 72 ppi)

External tank 119 is prepared for its trip from NASA's Michoud Assembly Facility in New Orleans to the Kennedy Space Center in Florida to be mated with the solid rocket boosters and Space Shuttle Discovery for the STS-121 mission. The space shuttle's external tank was returned to the Michoud facility for safety modifications including removal of the Protuberance Air Load, or PAL, Ramps. (NASA)+ Small (100 x 75, 72 ppi)