NASA engineers and contractors recently completed liftoff transition testing of a 67.5-inch model of the SLS in a 14-by-22-foot subsonic wind tunnel at NASA’s Langley Research Center in Hampton, Va. Data acquired from the test will help prepare SLS for its first mission in 2017, Exploration Mission-1, which will deliver an unmanned Orion spacecraft to a stable lunar orbit to check out the vehicle's fully integrated systems.

Wind tunnel tests are a tried-and-true method to understand the forces an object may endure as it moves through the atmosphere.

Instead of learning how environmental factors affect the SLS only during flight, engineers have started at the beginning to improve understanding of how the environment also affects the rocket while it's sitting on the pad, ready for liftoff.

"In a typical wind tunnel test, we point the model into the flow field," said John Blevins, lead engineer for aerodynamics and acoustics in the Spacecraft & Vehicle Systems Department at NASA's Marshall Space Flight Center in Huntsville, Ala. "For the liftoff test, that's not the case. The wind is actually traversing across the model at much higher angles -- simulating a liftoff environment."

Engineers tested four different payload configurations of the SLS, carrying up to 130 metric tons.

"The test data is key to ensure vehicle control as we lift off and pass the ground tower," Blevins added. "At supersonic speeds, engineers can more easily compute the forces and moments, but that's more challenging at low speeds. This test is low speed, with winds in the tunnel only reaching up to 160 miles per hour."

With winds up to 160 mph over the model, engineers can measure forces and moments that the air exerts over the vehicle. 

"Moments, or torque, act like a twisting force on the vehicle," explained Jeremy Pinier, research aerospace engineer in Langley’s Configuration Aerodynamics Branch.

Understanding forces and moments upon the vehicle at different wind conditions enables the vehicle to fly safely.

Engineers also used a technique for studying airflow streamlines called smoke flow visualization. Smoke is put into the wind flow and can be seen during testing. This allows engineers to see how the wind flow hits the surface of the model. "Understanding the flow patterns can give us insight into what we are seeing in the data," Pinier explained.

Now that the liftoff transition testing is complete, NASA engineers and contractors can apply their findings to the actual vehicle. 

"We will be using the data we receive from this test to run flight simulations on the actual SLS vehicle and assess its performance," Pinier said. "There’s nothing more motivating and exciting than contributing toward the design of a launch vehicle that will be travelling farther than humans have ever been."

The SLS capability is essential to America’s future in human spaceflight and scientific exploration of deep space. Only with a heavy-lift launch vehicle can humans explore our solar system, investigate asteroids and one day set foot on Mars. Marshall manages the SLS Program for the agency.

NASA engineers and contractors tested four different payload configurations during the liftoff transition testing of a 67.5-inch model of the SLS at NASA Langley Research Center’s 14-by-22-foot subsonic wind tunnel in Hampton, Va.

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Image Credit: 

NASA/LaRC

Quelle: NASA  

 

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Update: 9.12.2013

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NASA Engineers Crush Giant Fuel Tank To Improve Rocket Designs

Engineers position a 27.5-foot-diameter cylinder for the first full-scale Shell Buckling and Knockdown Factor Project test.

Image Credit: NASA/MSFC/Emmet Given

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Think of it as high-tech can crushing. Only the can is enormous, as big as part of the largest rocket ever made.

During a series of tests from Dec. 9-13 at NASA's Marshall Space Flight Center in Huntsville, Ala., engineers will apply nearly a million pounds of force to the top of an empty but pressurized rocket fuel tank. The test will eventually buckle and destroy the structure of the thin cylindrical tank wall while instruments precisely measure and record everything, millisecond by millisecond.

"What we learn will make it possible for NASA to design safe but still thinner and lighter structures for the Space Launch System and other spacecraft," said Dr. Mark Hilburger, senior research engineer in the Structural Mechanics and Concepts Branch at NASA's Langley Research Center in Hampton, Va.

In rocket science and engineering, every pound counts, and it costs to lift every pound to orbit. Rocket tanks are one of the heaviest parts of the rocket. If engineers can make tanks stronger and lighter, rockets can carry heavier payloads to space. That's the goal of the Shell Buckling and Knockdown Factor Project led by the NASA Engineering and Safety Center (NESC) in collaboration with Marshall and Langley teams.

Langley engineers are conducting their second full-scale tank test, nicknamed Can Crusher II, in Marshall's unique facility designed to test the full-size structures. Marshall engineers conducting the test have a keen interest in the results because the data will enhance the design of the heavy-lift Space Launch System (SLS), which is being developed by Marshall and will be the largest, most powerful rocket ever built.

Launch vehicles are composed of thin-walled cylindrical structures; if they are made lighter, buckling from the forces of launch and flight becomes a major concern. The project is developing a new, extremely accurate set of design standards for NASA and the aerospace industry, which has been using data that dates back to Apollo-era studies.

"In the 1960s when we went to the moon, those engineers did an amazing job with what they had," Hilburger said. "But they had to build conservative margins into their calculations because they didn't have today's materials or design, test and simulation tools. That means they built the launch vehicle heavier than it had to be, which can reduce the payload it can carry."

Since 2007, the Shell Buckling Knockdown Factors Project has been using cutting-edge test and analysis techniques to amass new data for design. The ultimate goal is to develop analyses and models that reflect the real-life test articles with extreme accuracy, so designers can use high-fidelity computer simulations and virtual tests to save time and money. "But we have to make sure that we ground those models in these carefully conducted real-world tests," Hilburger said.

In March 2011, the project team came to Marshall for what they believed to be the first test-to-failure of a full-scale, 27.5-foot-diameter, 20-foot-tall aluminum lithium test cylinder just for research purposes. It was reinforced with an orthogrid stiffener pattern, and the team squeezed it until it buckled, revealing the edges of the design margin.

The cylinder to be tested this time is External Tank-derived Test Article 2, or ETTA 2 Like ETTA 1 in 2011, it was built at Marshall from panels used for external tanks in the space shuttle program. This one is also 27.5 foot in diameter, the same diameter as SLS tanks, and 20 feet tall but will feature a different orthogrid stiffener pattern. Engineers can compare the results of this test to the first one to see if one pattern results in a stronger tank. At the top and bottom of the can are the load or pressure introduction structures made in the 1970s for the shuttle program.

"Using the heritage tank panels and Marshall’s valuable test facilities is saving millions in test dollars and time," Hilburger said.

The team prepared for next week's test to failure by running a series of sub-critical tests over the last few months. They've fitted the cylinder with more than 800 strain gauges, and 80 displacement transducers, and speckled ETTA 2 with markers used by a digital image correlation system. Cameras set up around the tank monitor the position of the dots during testing.

"We can actually track minute changes in the position of those dots and from that calculate displacements and strains on the entire test article," Hilburger said.

This week, there will be additional  exercises, and then the final day will be a test to failure scenario.

"We'll pressurize the structure to simulate an internal fuel pressure," Hilburger said. "And then we'll slowly start applying a combination of compression and bending to simulate a typical rocket flight condition."

Data from the team's work is already being incorporated into designs for the core stage of the SLS.

"When the new core stage flies, our design factors will be flying with it. It's very gratifying, but it's also nerve-wracking. When you're trying to reduce excess margins, you're obviously closer to failure, and want to make sure it's being done safely and with as much knowledge as possible.”

The shell buckling project activity has also given engineers at Marshall a great opportunity to hone skills. A lot of new technicians have received on-the-job training that will translate directly into SLS testing.

"This is my first large-scale structural test," said Matt Cash, lead test engineer for ETTA 2. "It's a fantastic experience, and everything I’m learning helps me prepare for SLS structural testing." Cash earned a degree in civil engineering with an emphasis on structures from the University of Alabama in Tuscaloosa. He's been a NASA employee for three years, and worked on the 2011 full-scale shell buckling test.

Because Marshall is one of the few places in the world where this kind of testing can be done, Cash said he's thrilled to be in the right place at the right time.

"The tests will provide extremely valuable data to SLS. I couldn't be happier to get to be a part of it."

Quelle: NASA

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Update: 9.01.2014

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SLS Avionics System Sees the (First) Light

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Test engineer James Peckham runs an avionics flight simulation to see how SLS will perform during launch.

Image Credit: Boeing

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The modern avionics system that will guide the most powerful rocket ever built saw the light -- the "first light," that is.

Hardware, software and operating systems for NASA's Space Launch System (SLS) recently were integrated and powered up for an inaugural run -- referred to as "first light."

When completed, SLS will be capable of powering humans and potential science payloads to deep space. It has the greatest capacity of any launch system ever built, minimizing cost and risk of deep space journeys.  

"We often compare the avionics system to the body's central nervous system -- we can't function without one, and neither can the SLS," said Lisa Blue, stages avionics system manager in the SLS Program Office at NASA's Marshall Space Flight Center in Huntsville, Ala. "Avionics tell the rocket where it should go and end up, and how it should pivot the engines to keep on the right trajectory."

"Now we have that critical system together, and each unit has powered up successfully," Blue added. "That's a major accomplishment toward getting ready for the first flight of SLS."

The Integrated Avionics Test Facilities team provided and installed the structure and simulation capability to model the environments the vehicle will experience during launch. With the avionics hardware units arranged in flight configuration on the structure and with the flight software, the facility will replicate what will actually fly the rocket. "We are using and testing state-of-the-art technology, including the most powerful computer processor ever used on a flight system," Blue said.

NASA and Boeing engineers will test the system in early January at the Systems Integration and Test Facility at the Marshall Center. They will run flight simulations to see how SLS will perform during launch.

"Completing the first light milestone establishes a capability to perform early avionics and software integration and testing to help us find and fix any problems with the system, and make sure the units communicate together as they are designed to do," said Dan Mitchell, SLS Integrated Avionics and Software lead engineer at the Marshall Center.        

Avionics and the flight computer will be housed in the SLS core stage. When completed, the core stage will be more than 200 feet tall and store cryogenic liquid hydrogen and liquid oxygen that will feed the vehicle's RS-25 engines. The Boeing Company is the prime contractor for the SLS core stage, including avionics.

In late January, the team will start working on the entire avionics system operating together as one unit. In 2015, the avionics will be shipped to NASA’s Michoud Assembly Facility in New Orleans, where the core stage is being manufactured, and integrated onto the actual rocket.

The first flight test of the SLS -- which will feature a configuration for a 70-metric-ton (77-ton) lift capacity and carry an uncrewed Orion spacecraft beyond low-Earth orbit to test the performance of the integrated system -- is scheduled for 2017. As the SLS evolves, it will provide an unprecedented lift capability of 130-metric-tons (143-tons) to enable missions even farther into our solar system to places like Mars.

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Avionics Set-up for Space Launch System

From left, Wayne Arrington, Gerald Clayton and Ryan MacKrell, all of The Boeing Company, work on setting up the avionics system in flight configuration in the Systems Integration and Test Facility at NASA's Marshall Space Flight Center. The units, which have powered up successfully and will undergo testing, will guide the most powerful rocket ever built -- NASA's Space Launch System.

Image credit: Boeing

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Quelle: NASA    

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Update: 16.01.2014

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NASA Space Launch System Could Make ‘Outside the Box’ Science Missions Possible

When it comes to scientific probes exploring the far reaches of our solar system, the rules could be changing.

The human spaceflight community joined the space science community Jan. 13-14 at the Outer Planets Assessment Group (OPAG) meeting in Tucson, Ariz. There, scientists heard from the Space Launch System (SLS) Program about the capabilities and progress being made on the rocket, and discussed the potential benefits it also could bring to robotic exploration of the outer solar system.

“The potential use of SLS for science will further enhance the synergy between scientific exploration and human exploration,” said John Grunsfeld, astronaut and associate administrator for science at NASA Headquarters in Washington. “SLS has the promise of enabling transformational science in our exploration of the solar system and cosmos.”

Currently under construction, NASA’s Space Launch System will be the world’s most powerful launch vehicle. Designed to enable human exploration missions to deep space destinations, including an asteroid and Mars, SLS is working toward a first launch in 2017. For that first flight test, the rocket will be able to launch 70 metric tons (77 tons) of payload into low-Earth orbit, almost three times what the space shuttle could carry. From there, SLS will be evolved to a configuration that will be able to carry 130 metric tons (143 tons), more weight than any rocket ever has been able to carry.

“While many people think of the Space Launch System in terms of human exploration, SLS could have a wide application in a lot of other areas, including space science,” said Steve Creech, assistant program manager for strategy and partnerships for SLS. “For missions to the outer planets, for example, SLS could make it possible to do things that are currently impossible, such as sending larger scientific spacecraft with more instruments to far off destinations with reduced transit times.”

Agency scientific and engineering teams have been evaluating whether there would be potential benefits from launching deep space robotic spacecraft, such as the Europa Clipper, a proposed mission to one of Jupiter's icy moons, on the SLS rocket, and determined the rocket would enable the spacecraft to fly direct trajectories to our solar system’s outer planets, rather than using planetary gravities to gain speed, reducing transit time compared to current launch vehicles. In the case of the Europa Clipper, for example, the transit time would be reduced to less than half of what it would be using other launch vehicles.

“For as long as people have been launching rockets into space, mission designers have had to work within certain limitations – a spacecraft can only be so heavy and it has to fit within a certain width,” Creech said. “Depending on how large you make it, it can only go so fast, which in some cases limits where you can go. Today, if you want to send a mission to the outer planets, you have to be able to make it fit within that box. With SLS, we’re about to make that box much larger.

“With the space shuttle, for example, we were able to launch missions like NASA’s Hubble Space Telescope that were about the size of a school bus. With SLS, you can design a spacecraft even larger than the space shuttle that carried Hubble. It’s going to open up an entirely new way of thinking about how we plan and design planetary science missions.”

NASA’s OPAG works to identify scientific priorities and pathways for exploration in the outer solar system past the asteroid belt, including the planets Jupiter, Saturn, Uranus, Neptune and their moons, and other destinations like comets and the distant Kuiper Belt Objects, including Pluto. The group actively solicits input from the scientific community and reports its findings to NASA Headquarters in Washington. OPAG provides input to NASA, is open to all interested scientists and regularly evaluates outer solar system exploration goals, objectives, investigations and required measurements on the basis of the widest possible community outreach. Current, NASA outer planets missions include the Cassini orbiter at Saturn and the New Horizons probe en route to Pluto.

The Advanced Concepts Office (ACO), at NASA’s Marshall Space Flight Center in Huntsville, Ala., where the SLS program also is managed, has been working to identify potential uses for the rocket that take advantage of its unique capabilities.

“The Space Launch System could be really game-changing for space science,” said ACO manager Reggie Alexander. “For some missions, it makes it much easier and quicker to carry them out. A Mars sample return mission, for example, could be flown using only one rocket instead of three. But for other destinations, SLS lets you do things we could only dream of before – like collecting samples from the geysers of Saturn’s moon Enceladus.”

Collaborative discussions such as the one at OPAG are part of NASA’s increased efforts to create synergies between its diverse programs.

“SLS is one piece in a much larger picture,” Creech said. “Human exploration missions will be drawing on the knowledge gained from programs like the International Space Station and the Curiosity rover on Mars, and, in turn, SLS could make it possible for other programs to do things they couldn’t do otherwise.”

NASA's Space Launch System will provide an entirely new capability for human exploration beyond Earth orbit using NASA’s Orion spacecraft. Designed to be flexible for crew or cargo missions, the SLS will be safe, affordable and sustainable to continue America's journey of discovery from the unique vantage point of space.

Quelle: NASA

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Excitement Building As NASA Continues Preparations For RS-25 Engine Testing

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Activity is growing in the A Test Complex at NASA's Stennis Space Center in MIssissippi as the agency prepares to take a giant step forward in its return to deep space.

Early in 2014, attention is on the A-1 Test Stand, which is being prepared to test RS-25 rocket engines that will power the core stage of NASA’s new Space Launch System (SLS). The rocket will carry humans to an asteroid and eventually Mars.

“This is a big year for Stennis, for NASA and for the nation’s human space program,” said Gary Benton, RS-25 rocket engine test project manager. “By mid-summer, we will be testing the engines that will carry humans deeper into space than ever before.

Renovation of the A-1 stand represents critical groundwork for such future missions. The A-1 test team completed gimbal, or pivot, testing of the J-2X rocket engine in early September, signaling the start of full-scale renovation efforts for RS-25 testing. Equipment installed on the A-1 stand for J-2X testing could not be used to test RS-25 engines because it did not match the new engine specifications and thrust requirements. For instance in flight, the J-2X engine is capable of producing 294,000 pounds of thrust. The RS-25 engine in flight will produce nearly twice as much -- about 530,000 pounds of thrust.

The first RS-25 engine is set to be delivered to the stand in May, and work is progressing, thanks to focused efforts of NASA officials and contractor teams.

A major task was completed on schedule in December with installation of a new thrust frame adapter on the stand. Each rocket engine type requires a thrust frame adapter unique to its specifications. Physically, the adapter is the largest facility item on the RS-25 testing preparation checklist.

Now, sights are set on upcoming work milestones, including:

 

Completing piping work needed to deliver rocket propellants for tests.

Installing necessary instrumentation.

Completing a readiness review in March, followed by early tests of new piping systems.

Installing equipment needed to accurately measure rocket engine thrust during tests.

Installing an initial RS-25 engine.

Completing preliminary tests of installed engine and a new rocket engine test controller.

Engineers are scheduled to conduct the first hotfire test on an RS-25 engine in July. Testing of RS-25 engines will continue for years to come then in order to power the nation’s ongoing human space program.

Anticipation is high, said Jeff Henderson, A-1 Test Stand director. “We’ve shown what we can accomplish here, and now, we have to continue in that same manner of excellence,” he explained. “We just have to stay focused on what it’s all about.”

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A thrust frame adapter is lifted onto the A-1 Test Stand at NASA’s Stennis Space Center in the closing days of 2013.

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RS-25 Engine Thrust Frame Adapter

A RS-25 thrust frame adapter is positioned into place for mounting onto the A-1 Test Stand at NASA’s Stennis Space Center. Four RS-25 engines will power the core stage of NASA’s new Space Launch System (SLS), which is being built to carry humans deeper into space than ever. Testing of the RS-25  engines at Stennis is scheduled to begin in mid-summer, after test stand modifications are completed.

Quelle: NASA

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Update: 19.01.2014

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NASA prepare for Space Launch System engine tests

NASA is making preparations for testing the engines which will power the core stage of its next rocket, the Space Launch System (SLS).

The SLS will have four RS-25 engines -- the same type which powered the space shuttle -- to power its core stage. Each engine is designed to provide 530,000 pounds of thrust.

The testing of the engines is due to begin this summer at NASA's Stennis Space Center in Mississippi. A test platform is being prepared for the installation of the first RS-25 engine arriving in May ahead of a hot-fire test in July.

Years of tests are expected before SLS's maiden flight scheduled for 2017. RS-25 rocket engine test project manager Gary Benton said: “This is a big year for Stennis, for NASA and for the nation’s human space program. By mid-summer, we will be testing the engines that will carry humans deeper into space than ever before."

The SLS is being designed with two configurations, one that can lift 70 metric tons and a larger configuration with a second stage that will be capable of lifting 130 metric tons.

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An RS-25 during a previous hot-fire test. Four RS-25 engines will power the core stage of NASA’s new Space Launch System (SLS). Image credit: Aerojet Rocketdyne

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Whilst the core stage will be powered by RS-25 engines, the second stage will be powered by J-2X engines which were tested at the Stennis Space Center last year.

In its larger configuration SLS will stand 384 feet tall, higher than the Saturn V rocket that took the Apollo craft to the Moon. The Saturn V rocket stood 363 feet tall (110 metres) and could lift 120 metric tons to Low Earth Orbit.

NASA hopes the SLS will be used to launch its Orion space vehicle to deep space destinations such as an asteroid and eventually Mars. Further parachute tests for Orion were conducted in recent days as the space agency works towards the spacecraft's first unmanned test flight - Exploration Flight Test-1 (EFT-1) - scheduled for this September.

The EFT-1 mission will see Orion orbit Earth twice at an altitude of 3,600 miles (about 5,800 km) - farther than any spacecraft designed to carry crew has reached since the last Apollo mission.

Quelle: SEN

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Update: 21.05.2014

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Breaking Ground: Making History: Space Launch System Structural Test Stands to be Built at Marshall Space Flight Center

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Artist concept of Test Stand 4693 at NASA's Marshall Space Flight Center. The 215-foot stand will be used for structural loads testing on the liquid hydrogen tank for the Space Launch System core stage.

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NASA’s Space Launch System (SLS) will have the largest cryogenic fuel tanks ever used on a rocket. Stands to test the tanks and other hardware to ensure that these huge structures can withstand the incredible stresses of launch will be built at NASA’s Marshall Space Flight Center in Huntsville, Alabama.

NASA is contracting for the construction of the test stands through the U.S. Army Corps of Engineers, which has awarded a $45.3 million contract to Brasfield & Gorrie of Birmingham, Alabama.

SLS will be the most powerful rocket in history and the launch vehicle that will send astronauts in NASA's Orion spacecraft beyond low-Earth orbit into the solar system on missions to an asteroid and eventually to Mars.

The test stands will be used for the SLS core stage, which will store cryogenic liquid hydrogen and liquid oxygen. The core stage is made up of the engine section, liquid hydrogen tank, intertank, liquid oxygen tank and forward skirt. As the five parts of the core stage are manufactured, they will be shipped by barge from NASA's Michoud Assembly Facility in New Orleans to Marshall for testing.

"These stands are necessary to accommodate the sheer size of the core stage components, and the extreme loads we are putting on them -- some up to 9 million pounds," said Tim Gautney, element discipline lead engineer for SLS core stage testing. "We will use hydraulic cylinders to push, pull, twist and bend these pieces to make sure they can withstand the loads and environments they may experience on the launch pad and upon ascent. The tests also will verify the models already in place that predict the amount of loads the core stage can endure."

The 215-foot stand, Test Stand 4693, with a twin-tower configuration, will be made with 2,150 tons of steel. It will be used for testing the liquid hydrogen tank, which will be 185 feet when completed. The tank will be placed in the stand vertically, and be loaded with liquid nitrogen for stress testing. It is being built on the foundation of the stand where the Saturn V F-1 engine was tested.

The second test stand, Test Stand 4697, is a 692-ton steel structure about nine stories high, or 85 feet. It will be used to test the liquid oxygen tank and forward skirt in Marshall's West Test Area. "Within the foundation of this stand, we have 1.75 miles of embedded anchor rods -- that gives you an idea of the type of stability we need to test these parts with such high-level force," said Byron Williams, project manager for the liquid oxygen tank and forward skirt test stand.

The estimated year-long construction is expected to begin in late May.

NASA and the Corps entered into an agreement for construction of the test facilities and NASA transferred funds to the Corps for this purpose. The facilities were designed by a joint venture team of the architecture and engineering firms Goodwyn Mills and Cawood, of Montgomery, Alabama, and Merrick & Company of Greenwood Village, Colorado.

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NASA Pegasus Lastkahn, letzter seiner Art, erhält neues Leben

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The Pegasus barge, with its tugboat escort, readies for departure from NASA's Kennedy Space Center, Florida, on Nov. 10, 2011, bound for NASA's Stennis Space Center near Bay St. Louis, Mississippi.

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NASA's Pegasus barge, which throughout the space shuttle era ferried shuttle external tanks and other hardware from NASA's manufacturing site in New Orleans to its Florida launch facilities, is about to cast off on a new mission as part of NASA's efforts to send humans to deep space.

Conrad Shipyard LLC of Morgan City, Louisiana, has been awarded an $8.5 million contract to refurbish the long-serving Pegasus craft, which will begin transporting rocket components for NASA's next-generation Space Launch System (SLS) between manufacturing, testing and launch locations.

NASA is collaborating in the barge's return to service with the U.S. Army Corp of Engineers' Marine Design Center, headquartered in Philadelphia, which made the contract award May 14. NASA's Marshall Space Flight Center in Huntsville, Alabama, maintains the barge for the agency.

"Pegasus made it possible for NASA to deliver numerous groundbreaking science missions to orbit and complete construction of the International Space Station," said Robert Rutherford, group lead for the Transportation and Logistics Engineering Office at Marshall.

"It's incredibly rewarding to know Pegasus will carry on its long tradition of service, supporting the nation's missions in space," Rutherford added.

The Pegasus, 260 feet long, 50 feet wide and 15 feet high, has been housed at NASA's Stennis Space Center near Bay St. Louis, Mississippi, since 2011, when it completed its final space shuttle-related operation: delivering shuttle main engine ground support equipment to Stennis from NASA's Kennedy Space Center in Florida.

Previously, the barge sailed between NASA's Michoud Assembly Facility in New Orleans, where the space shuttle external tanks were manufactured, and Kennedy, home to space shuttle launch operations for 30 years and the launch site for the Space Launch System's missions to future destinations including an asteroid and Mars.

Pegasus was specially designed and built for that 900-mile sea journey from the Louisiana shore to the eastern Florida coast, which includes both inland and open-ocean waterways. It made the trip 41 times between 1999 and 2011, delivering 31 space shuttle external tanks: ET-103, ET-105, ET-106, ET-108, ET-110, ET-111, ET-113 and ET-115 through ET-138.

Built to replace NASA's aging Poseidon and Orion barges -- both built in the 1940s to serve in World War II and converted in the 1960s for NASA's Apollo program -- Pegasus in 2002 became the sole means of transport for the shuttle external tanks. Today, it's the only barge of its kind in NASA's inventory.

What's ahead for Pegasus

To manage SLS hardware and components, dramatically larger than space shuttle propulsion elements, Conrad Shipyard is tasked with lengthening the barge from 260 feet to 310 feet. The company also will perform all necessary maintenance and refurbishment to ensure the restored vessel meets American Bureau of Shipping standards, including load line certification, or verification of the barge's legal loading limit to safely maintain buoyancy during water travel. The American Bureau of Shipping is a leading marine and offshore classification society which performs technical reviews, audits and surveys for seagoing vessel certification.

Bristol Harbor Group of Bristol, Rhode Island, in partnership with the Marine Design Center, will perform some of the architecture and engineering work for the barge modification.

Conrad will tow Pegasus from Stennis to the company's shipyard facilities in Amelia, Louisiana, where it will be drydocked during repair/refit operations.

Work is expected to be completed in early 2015, readying Pegasus to set sail once more.

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Engineers Test NASA’s SLS Booster Forward Skirt to the Limits

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NASA and ATK engineers complete structural loads testing on the Space Launch System (SLS) booster forward skirt at ATK’s facility in Promontory, Utah.

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A critical connection between NASA’s new rocket and its twin solid rocket boosters that will help it get to space proved it could withstand millions of pounds of launch stress during a series of ground tests that ended May 20.

The booster forward skirt, which houses the electronics responsible for igniting, steering and jettisoning the two five-segment boosters and carries most of the forces acting on the boosters during launch, is one of two places at the top and bottom of the booster where it is attached by struts to the Space Launch System (SLS) core stage. The core stage, towering more than 200 feet tall with a diameter of 27.6 feet, will store cryogenic liquid hydrogen and liquid oxygen that will feed the vehicle’s RS-25 engines.

When completed, SLS will be capable of taking a crew and cargo on deep space missions, including to an asteroid and eventually Mars.

The five-segment boosters used during the launch of SLS will be the world's largest solid propellant rockets, measuring 177 feet long and 12 feet in diameter. ATK of Promontory, Utah, is the prime contractor for the boosters.

Loads on the hardware are forces -- primarily driven by mass and vehicle acceleration -- applied at different points on the vehicle. Structural loads tests are performed to ensure each piece of hardware can endure loads without any adverse effects to the vehicle, or most importantly, to the crew.

For the forward skirt test, conducted at ATK's facility in Promontory, engineers used increments of force -- about 200,000 pounds per minute -- to prove the design capabilities meet the strength requirements, with sufficient margin. The structure was also subjected to a combination of axial and lateral loads, which are critical at liftoff.

"Data will be reviewed over the coming weeks," said Brian Pung, SLS booster structures & assembly team lead at NASA's Marshall Space Flight Center in Huntsville, Alabama, where the SLS Program is managed. "We are very pleased with the initial results. Completion of this test brings us closer to use of this heritage hardware on SLS."

The team intentionally took the hardware beyond required margins -- not typical for structural loads testing on this scale.

"Attempting to take a structure of this size to failure is somewhat unique for structural testing," said Shane Canerday, forward assembly subsystem manager at the Marshall Center. "We want to know the exact amount of force the hardware can take to address capability differences that may exist across the fleet of heritage forward skirts."

The SLS 70-metric-ton (77 ton) initial configuration will launch an uncrewed Orion spacecraft to demonstrate the integrated system performance of the SLS rocket and spacecraft prior to a crewed flight. The massive 130-metric-ton configuration will be the most capable, powerful launch vehicle in history for crewed, longer duration missions.

Quelle: NASA