NASA SLS Propulsion System Goes into Marshall Stand Ahead of Big Test Series
A test version of the interim cryogenic propulsion stage (ICPS) for NASA's Space Launch System rocket is loaded into the test stand at the agency's Marshall Space Flight Center in Huntsville, Alabama. Two simulators and four qualification articles of the upper part of the SLS will be stacked in the stand and subjected to forces similar to those experienced in flight. The ICPS joins the core stage simulator and launch vehicle stage adapter, which were loaded into the test stand earlier this fall.
Credits: NASA/MSFC/Brian C. Massey
NASA engineers installed a test version of a crucial piece of hardware for the Space Launch System rocket in a 65-foot-tall test stand Nov. 17 at the agency's Marshall Space Flight Center in Huntsville, Alabama. SLS will be the most powerful rocket ever built for human missions to deep space with the Orion spacecraft, including the Journey to Mars.
The hardware is a test version of the interim cryogenic propulsion stage (ICPS), which is a liquid oxygen/liquid hydrogen-based system that will give Orion the in-space push needed to fly beyond the moon before it returns to Earth on the first flight of SLS and Orion in late 2018. The ICPS will be stacked with three other test articles and two simulators that make up the upper portion of the SLS rocket ahead of a rigorous test series in early 2017.
"The installation of the ICPS is another big step in getting ready for the test series, which will ensure that the hardware can endure the incredible stresses of launch," said Steve Creech, deputy manager of the Spacecraft and Payload Integration & Evolution Office at Marshall, which manages the SLS Program for the agency. "In addition to testing, work is underway on flight pieces of the upper part of the rocket, including the ICPS. NASA and our prime contractor teams are working diligently toward mission success for first flight, and this test series also will provide crucial data to support future missions, including the journey to Mars."
The ICPS is the liquid oxygen/liquid hydrogen-based propulsion stage that will give NASA's Orion spacecraft the in-space push needed to fly beyond the moon before it returns to Earth on the first flight of SLS and Orion in 2018.
Credits: NASA/MSFC/Brian C. Massey
The ICPS test article, without the engine, is around 29 feet tall and 16.8 feet in diameter. It is the largest piece of hardware for the test series, and was designed and built by The Boeing Co. in Huntsville and United Launch Alliance of Decatur.
The hardware -- some being almost exact to flight specifications -- will be pushed, pulled and twisted during the tests. The ICPS joins two other pieces of hardware already installed in the stand. The core stage simulator was loaded into the test stand Sept. 21, with the launch vehicle stage adapter (LVSA) following on Oct. 12. The core stage simulator is a duplicate of the top of the SLS core stagethat is approximately 10 feet tall and 27.5 feet in diameter. It was designed and built at Marshall.
The LVSA connects the SLS core stage and the ICPS. The LVSA test hardware is 26.5 feet tall, with a bottom diameter of 27.5 feet and a top diameter of 16.8 feet. It was designed and built by prime contractor Teledyne Brown Engineering of Huntsville. The other three qualification articles and the Orion simulator will complete the stack later this fall. Approximately 50 test cases are planned for the upcoming series.
The initial SLS configuration will have a minimum 70-metric-ton (77-ton) lift capability and be powered by twin solid rocket boosters and four RS-25 engines. The next planned upgrade of SLS will use a more powerful exploration upper stage for more ambitious missions with a 105-metric-ton (115-ton) lift capacity.
ESA TO SUPPLY SERVICE MODULE FOR FIRST CREWED ORION MISSION
ESA and NASA are extending their collaboration in human space exploration following confirmation that Europe will supply a second Service Module to support the first crewed mission of the Orion spacecraft.
Orion with European Service Module
The Service Module provides propulsion, electrical power, water and thermal control as well as maintaining the oxygen and nitrogen atmosphere for the crew.
The mission is set for launch from NASA’s Kennedy Space Center in Florida, USA, as early as 2021 and will include up to four astronauts – the first time humans have left low orbit since 1972. Crew size and composition will be determined closer to launch.
The mission will see Orion follow three progressively elongated orbits to reach past the Moon and return to Earth, faster than any manned spacecraft has reentered our atmosphere before.
ESA’s Director of Human Spaceflight, Dave Parker, says, “We are excited to be a part of this historic mission and appreciate NASA’s trust in us to help extend humanity’s exploration farther afield into our Solar System.”
The first Orion with the service module will be launched in late 2018 on NASA’s new Space Launch System. The month-long mission will be unmanned and will orbit the Moon before returning to Earth, testing the spacecraft and rocket before carrying astronauts.
Automated Transfer Vehicle
The European Service Module is designed, built and assembled by a team of companies from 11 countries led by Airbus Space & Defence, based on proven technology from ESA’s Automated Transfer Vehicle that flew to the International Space Station five times with supplies.
The mission and collaboration with NASA is part of ESA’s vision to prepare for future voyages of exploration further into the Solar System, and continues the spirit of international cooperation that forms the foundation of the International Space Station.
Major Assembly Complete on System that will Pack a Powerful Push for Orion
The propulsion system that will give the Orion spacecraft the in-space push needed to travel thousands of miles beyond the moon and back has completed major assembly at United Launch Alliance (ULA) in Decatur, Alabama. The Boeing-designed interim cryogenic propulsion stage (ICPS) is a liquid oxygen/liquid hydrogen-based system that will give Orion an extra punch of power on the first, uncrewed flight of the spacecraft with NASA's new rocket, the Space Launch System in late 2018. The first integrated exploration mission will allow NASA to use the lunar vicinity as a proving ground to test systems farther from Earth, and demonstrate Orion can get to a stable orbit in the area of space near the moon in order to support sending humans to deep space, including the Journey to Mars. With major assembly now complete on the flight hardware, the ICPS has several more steps to go, including avionics installation at the ULA-Decatur factory; barge and road transport to the Delta Operating Center at Cape Canaveral, Florida, for avionics and system-level testing; and delivery to NASA in mid-2017.
Image credit: ULA
NASA Readies for Major Orion Milestones in 2017
From the beginning of assembly work on the Orion crew module at NASA’s Kennedy Space Center in Florida to testing a range of the spacecraft systems, engineers made headway in 2016 in advance of the spacecraft’s 2018 mission beyond the moon.
Inside the Neil Armstrong Operations and Checkout Building at NASA’s Kennedy Space Center in Florida, Lockheed Martin technicians monitor the progress as a crane lowers the Orion crew module structural test article (STA) onto a test tool called the birdcage.
From the beginning of assembly work on the Orion crew module at NASA’s Kennedy Space Center in Florida to testing a range of the spacecraft systems, engineers made headway in 2016 in advance of the spacecraft’s 2018 mission beyond the moon. A look at the important milestones that lie ahead in the next year give a glimpse into how NASA is pressing ahead to develop, build, test and fly the spacecraft that will enable human missions far into deep space.
Orion Power On
The NASA and Lockheed Martin team at Kennedy spent much of 2016 integrating structural elements into the spacecraft, and then began incorporating critical systems such as avionics components and propulsion tubing. In the spring of 2017, computers in the Orion crew module for the spacecraft’s first mission with NASA’s Space Launch System will be turned on for the first time to verify the spacecraft can route power and send commands. It’s an essential integrated test that will verify Orion’s systems are connected and responding as planned.
Service Module Arrival Stateside
The European-built service module for Orion, which will propel and power it in space, is an essential component of the spacecraft and extends NASA’s international collaboration with ESA in human spaceflight into deep space. The service module for Orion’s upcoming flight will be shipped to Kennedy, after structural and systems work is completed at the facility of ESA contractor Airbus Defence & Space in Bremen, Germany.
Orion’s heat shield will be secured onto the crew module in the summer, and the crew and service modules will subsequently be stacked together. Both operations are essential steps to be completed ahead of the early 2018 shipment of the entire stack to NASA Glenn’s Plum Brook Station in Ohio, where the craft will be put through a series of tests to ensure it is ready for the dynamics of launch and the harsh environment of deep space flight.
Construction Begins on First Orion for Crew
While the Orion outfitting and assembly process for the first mission of the spacecraft atop the Space Launch System rocket continues in 2017, construction will also begin on the vehicle for the first Orion flight with astronauts that will fly as early as 2021. The first panels of the crew module pressure vessel for that mission are expected to arrive at NASA’s Michoud Assembly Facility in New Orleans in the spring, when weld operations will begin.
Testing, Testing, Testing
Testing on the ground plays a vital role in ensuring Orion is fit enough for what it will face in space, and a variety of tests are planned for the coming year. A structural test article will move to Lockheed Martin’s facility near Denver for a variety of mechanism separation, acoustic and pressure testing. Several parachute tests will take place in the skies above the Arizona desert to ensure Orion is ready to bring home crew, and a variety of human factors testing such as legibility tests, will help evaluate how the crew interacts with the spacecraft.
NASA’s First Flight With Crew Will Mark Important Step on Journey to Mars
When astronauts are on their first test flight aboard NASA’s Orion spacecraft, which will take them farther into the solar system than humanity has ever traveled before, their mission will be to confirm all of the spacecraft’s systems operate as designed in the actual environment of deep space. After an Orion test campaign that includes ground tests, systems demonstrations on the International Space Station, and uncrewed space test flights, this first crewed test flight will mark a significant step forward on NASA’s Journey to Mars.
This will be NASA’s first mission with crew in a series of missions in the proving ground, an area of space around the moon where crew can build and test systems needed to prepare for the challenge of missions to Mars. The mission will launch from NASA’s Kennedy Space Center Florida as early as August 2021. Crew size will be determined closer to launch, but NASA plans to fly up to four astronauts in Orion for each human mission.
“Like every test flight, we will have test objectives for this mission both before and after we commit to going to the moon,” said Bill Hill, deputy associated administrator, Exploration Systems Development, NASA Headquarters in Washington. “It’s just like the Mercury, Gemini, and Apollo programs, which built up and demonstrated their capabilities over a series of missions. During this mission, we have a number of tests designed to demonstrate critical functions, including mission planning, system performance, crew interfaces, and navigation and guidance in deep space.”
The mission plan for the flight is built around a profile called a multi-translunar injection (MTLI), or multiple departure burns, and includes a free return trajectory from the moon. Basically, the spacecraft will circle our planet twice while periodically firing its engines to build up enough speed to push it toward the moon before looping back to Earth.
After launch, the spacecraft and upper stage of the rocket will first orbit Earth twice to ensure its systems are working normally. Orion will reach a circular orbit at an altitude of 100 nautical miles and last 90 minutes. The move or burn to get the spacecraft into a specific orbit around a planet or other body in space is called orbital insertion.
Following the first orbit, the rocket’s powerful exploration upper stage (EUS) and four RL-10 engines will perform an orbital raise, which will place Orion into a highly elliptical orbit around our planet. This is called the partial translunar injection. This second, larger orbit will take approximately 24 hours with Orion flying in an ellipse between 500 and 19,000 nautical miles above Earth. For perspective, the International Space Station orbits Earth from about 250 miles above.
Once the integrated vehicle completes these two orbits, the EUS will separate from Orion and any payloads selected and mounted inside the rocket’s universal stage adapter will be released. The payloads will then fly on their own to conduct their unique missions.
After the EUS separation, the crew will do a unique test of Orion’s critical systems. They will gather and evaluate engineering data from their day-long orbit before using Orion’s service module to complete a second and final propulsion move called the translunar injection (TLI) burn. This second burn will put Orion on a path toward the moon, and will conclude the “multi-translunar injection” portion of the mission.
“Free” ride home
The TLI will send crew around the backside of the moon where they will ultimately create a figure eight before Orion returns to Earth. Instead of requiring propulsion on the return, the spacecraft will use the moon’s gravitational pull like a slingshot to bring Orion home, which is the free return portion of the trajectory. Crew will fly thousands of miles beyond the moon, which is an average of 230,000 miles beyond the Earth.
A flexible mission length will allow NASA to gather valuable imagery data during daylight for the launch, landing and recovery phases. It will take a minimum of eight days to complete the mission, and pending additional analysis, it may be extended up to 21 days to complete additional flight test objectives.
Two missions, two different trajectories
The agency is scheduled to test SLS and Orion together for the first time without crew over the course of about three weeks in late 2018. The MTLI will build upon testing that will be done in a distant lunar retrograde orbit, or DRO, for that first mission. The DRO will put Orion in a more challenging trajectory, and will be an opportunity to test the kind of maneuvers and environments the spacecraft will see on future exploration missions. The DRO will require additional propulsion moves throughout the trip, including a moon flyby and return trajectory burns.
“Between the DRO on our first flight, and the MTLI on the second flight, we will demonstrate the full range of capabilities SLS and Orion need to operate in deep space,” said Hill.
Once these first two test flights are completed, Hill added that NASA hopes to begin launching missions every year with crew, depending on budget and program performance.
NASA recently outlined its exploration objectives in deep space and grouped them into three categories: transportation, working in space, and staying healthy. The early missions in the proving ground are a critical step on the journey to learn more about the deep space environment and test the technologies the agency needs to eventually take humans to Mars.
Wind Tunnel Testing Underway for Next, More Powerful Version of NASA's Space Launch System
Dr. Patrick Shea inspects a nearly 4 3/4-foot (1.3 percent scale) model of the second generation of NASA's Space Launch System in a wind tunnel for ascent testing at NASA's Ames Research Center in Silicon Valley, California. The tests will help determine the larger, more powerful rocket's behavior as it climbs and accelerates through the sound barrier after launch. To also test a new optical measurement method, Ames engineers coated the SLS model with Unsteady Pressure-Sensitive Paint, which under the lighting glows dimmer or brighter according to the air pressure acting on different areas of the rocket. Shea, who is from NASA's Langley Research Center in Hampton, Virginia, was SLS aerodynamic test lead for the work at Ames.
As engines are fired, software written and hardware welded to prepare for the first flight of NASA's Space Launch System (SLS), engineers are already running tests in supersonic wind tunnels to develop the next, more powerful version of the world's most advanced launch vehicle capable of carrying humans to deep space destinations.
"Aeronautics leads the way in the design of a new rocket," said Jeff Bland, SLS discipline lead engineer for Integrated Vehicle Structures & Environments at NASA's Marshall Space Flight Center in Huntsville, Alabama. "The first leg any journey for spacecraft launched from Earth is a flight through our atmosphere."
The next generation of NASA's Space Launch System will be 364 feet tall in the crew configuration, will deliver a 105-metric-ton (115-ton) lift capacity and feature a powerful exploration upper stage. On SLS’s second flight with Orion, the newer rocket will carry up to four astronauts on a mission around the moon, in the deep-space proving ground for the technologies and capabilities needed on NASA’s Journey to Mars.
The new wind tunnel tests are for the second generation of SLS. It will deliver a 105-metric-ton (115-ton) lift capacity and will be 364 feet tall in the crew configuration -- taller than the Saturn V that launched astronauts on missions to the moon. The rocket's core stage will be the same, but the newer rocket will feature a powerful exploration upper stage. On SLS’s second flight with Orion, the rocket will carry up to four astronauts on a mission around the moon, in the deep-space proving groundfor the technologies and capabilities needed on NASA’s Journey to Mars.
Scale models of the upgraded rocket in crew and cargo configurations are being carefully positioned in wind tunnels for test programs to obtain data needed to refine the design of the rocket and its guidance and control systems, said Dr. John Blevins, SLS lead engineer for aerodynamics and acoustics at Marshall. During hundreds of test runs at NASA's Langley Research Center in Hampton, Virginia, and Ames Research Center in Silicon Valley, California, engineers are measuring the forces and loads that air induces on the launch vehicle during every phase of its mission.
"All the critical aerodynamic environments, from when the upgraded rocket leaves the Vehicle Assembly Building at Cape Canaveral to launch, acceleration through the sound barrier and booster separation at greater than Mach 4 are evaluated in these four tests," Blevins said.
Ascent tests completed at Ames in November determined the rocket's behavior as it climbs after launch, and the kind of instructions to be programmed into the rocket flight computer for guidance and control as the rocket passes through transonic flight. For instance, the tests will determine what commands the autopilot will send to the rocket's nozzles to correct for wind or other factors and stay on course.
Buffet testing at Langley in November focused primarily on how the cargo version of the upgraded rocket behaves as it moves through the atmosphere at just below the speed of sound, approaching about 800 miles per hour, then moves into supersonic flight. As the rocket approaches the speed of sound, shock waves build and move along different points of the launch vehicle. These shock waves can cause buffeting, shaking, vibration and unsteady loads that could result in damage or course changes that must be corrected, Blevins said.
The cargo version of the upgraded rocket has a smooth fairing above the exploration upper stage instead of the Orion spacecraft and launch abort system, so separate wind tunnel testing is needed. Similar tests planned for the fall 2017 at Langley will include observing this transonic shock oscillation and buffeting on the crew version of the rocket, at both subsonic speeds and higher Mach numbers. At Mach 1.5 or 2, the waves terminate, or remain at the same points on the rocket for the rest of the flight, but they continue to change angle and strength.
These wind tunnel tests are critical, Blevins said, because the location and temporal behavior of these shock waves are difficult to predict with computational fluid dynamics -- they must be observed and measured.
Two other test series are planned at Langley. The first in early 2017 will provide data to ensure that as the SLS’s two solid rocket boosters separate from the rocket during ascent, they don't come back into contact with the vehicle. These tests are complex, Blevins said, because the models of the rocket’s core stage and each of the two boosters are separately instrumented, and even the dynamics of the small rocket motors that jettison the boosters are simulated.
Next will be liftoff transition testing, scheduled in the summer. These tests will include evaluation of the effects of winds on the rocket as it is waiting on the pad, and the presence of the mobile launcher and tower during liftoff. Drift of the vehicle as it moves past the tower must be controlled to avoid damage and because the sound bouncing back from the pad can cause damaging vibration.
"We expect that at the end of this test series we will have all the aerodynamic flight data needed for the upgraded rocket," he said. "We'll be ready for the first flight with crew, targeted as early as 2021, and subsequent flights."
NASA engineers have also teamed with CUBRC Inc. of Buffalo, New York, to use a special type of wind tunnel to better understand and analyze how the SLS heats up as it ascends into space. A model of the rocket was used in the first phase of aerodynamic heating tests in CUBRC's Large Energy National Shock Tunnel (LENS-II) in September. A second phase of testing is planned for models of the SLS in crew and cargo versions, in early 2017.
The SLS wind tunnel testing is very much a cross-agency effort resulting in information and new test techniques that also benefit other rocket and aerospace programs, said Dr. Patrick Shea. He's based at Langley, but served as SLS aerodynamics test lead for the transonic ascent testing recently completed at the Ames facilities.
For example, the Ames aerodynamics team is developing an optical measurement method involving Unsteady Pressure-Sensitive Paint. During a test, special lights and cameras will observe changes in the paint's fluorescence, indicating the strength of aerodynamic forces acting along different areas of the rocket or test article. Ames was able to take advantage of the presence of the SLS rocket model to conduct its own tests using the paint.
"For a lot of aero-acoustics and buffet work, we instrument the models with hundreds of pressure sensors. If we can start moving to more of an optical technique such as the dynamic pressure sensitive paint, it will really make good strides forward," Shea said. "It ended up being a really nice integration of their test technique and our test campaign."
Shuttle engine delivered to Orion service module assembly site
A former space shuttle orbital maneuvering system engine has been delivered to Germany for attachment to the European-built service module destined to steer NASA’s next Orion spacecraft on a course around the moon on an uncrewed test flight in late 2018.
The engine was refurbished and reassembled at NASA’s White Sands Test Facility in New Mexico, then shipped to Johnson Space Center in Houston for shake testing and returned to White Sands for leak tests, according to a European Space Agency blog post.
It flew from Dallas/Fort Worth International Airport to Frankfurt last month, and then continued its journey by truck to Airbus Defense and Space’s spacecraft assembly facility in Bremen, Germany, ESA said.
ESA is providing the service modules for at least the next two Orion missions — an unpiloted shakedown cruise in lunar orbit scheduled to lift off in November 2018, and the first Orion flight with astronauts on-board in the early 2020s.
European governments agreed to pay for the service module for the 2018 flight, named Exploration Mission-1, at a meeting of government ministers in December 2012. ESA member states last month committed funding for a second service module for Exploration Mission-2, which will carry up to four astronauts farther than the moon’s orbit as soon as 2021.
Airbus Defense and Space is in charge of building the service modules at its Bremen plant. Lockheed Martin is prime contractor for the Orion crew module, which will house the astronauts, their living quarters and the cockpit.
The service modules provide propulsion, propellants, electricity, water, oxygen, nitrogen and thermal control for the Orion spacecraft.
The service module has 33 engines and thrusters to control the Orion capsule’s orientation and adjust its trajectory after launch. The main engine for EM-1 is a refurbished Orbital Maneuvering System engine that flew on 19 space shuttle missions.
The OMS engines were mounted on pods on each side of the shuttle’s vertical tail, used to change the craft’s orbit and begin the spaceship’s trip back to Earth with a de-orbit burn.
The engines burn hydrazine and nitrogen tetroxide propellants, and were each rated for 100 missions, rated for multiple restarts on each flight.
Aerojet Rocketdyne built the OMS engines, which provide around 6,000 pounds of thrust in vacuum.
The OMS engine slated to launch on EM-1 flew on the shuttle Challenger, Discovery and Atlantis in its career. Its first launch was on the STS-41G mission in October 1984, and its last shuttle mission on STS-112 in October 2002, according to Rachel Kraft, a NASA spokesperson.
The EM-1 mission will last more than three weeks, sending the Orion spacecraft into a high-altitude retrograde orbit around the moon before heading back to Earth for a splashdown in the Pacific Ocean.
The European-built service module is in the “critical path” for EM-1’s to remain on track for its launch readiness window, which runs from September through November of 2018. The service module is due for delivery to NASA’s Kennedy Space Center in Florida in April — after engineers in Germany add the OMS engine and propellant tanks to the already-finished primary structure.
An on-time delivery of the service module is critical to maintain EM-1’s target launch date, unless engineers find a way to make up time once the power and propulsion segment is in the United States.
At KSC, ground crews will connect the service module with the Orion crew module, then ship the spacecraft to NASA’s Plum Brook Station in Ohio by the end of 2017 to subject it to the extreme temperatures and vacuum conditions it will encounter in space.
The craft will return to KSC in early 2018 for final assembly steps, including the spacecraft’s fueling and the addition of the Orion launch abort system before the stack is mounted on top of NASA’s Space Launch System inside the Vehicle Assembly Building for rollout to launch pad 39B.
The agreement last month for ESA to supply a second service module came after European governments extended their support of the International Space Station through 2024. ESA is providing the two service modules for EM-1 and EM-2 as part of a barter agreement to pay NASA for its share of the space station’s operating costs.
“We are excited to be a part of this historic mission and appreciate NASA’s trust in us to help extend humanity’s exploration farther afield into our solar system,” said David Parker, ESA’s director of human spaceflight, after the ministerial meeting in Switzerland last month.
Construction Complete: Stand Prepares to Test SLS’s Largest Fuel Tank
In this 60-second time-lapse video, watch structural Test Stand 4693 at NASA's Marshall Space Flight Center rise 221 feet, from the start of construction in May 2014 to its end in December 2016. Test Stand 4693 will subject the 537,000-gallon liquid hydrogen tank of the Space Launch System's massive core stage to the same stresses and pressures it must endure at launch and in flight.
Credits: NASA/MSFC Video
Robert Bobo, left, and Mike Nichols talk beneath the 221-foot-tall Test Stand 4693, the largest of two new Space Launch System test stands at NASA's Marshall Space Flight Center in Huntsville, Alabama. Bobo manages SLS structural strength testing, and Nichols is lead test engineer for the SLS liquid hydrogen tank, which the stand will subject to the forces it must endure during launch and flight. This stand and Test Stand 4697, where the SLS liquid oxygen tank will be tested, were designed and developed by Marshall’s Test Laboratory and the Office of Center Operations. The U.S. Army Corps of Engineers provided oversight for the construction contract for the government. Construction partners included general contractor Brasfield & Gorrie of Birmingham, Alabama; architects Goodwyn, Mills and Cawood of Montgomery, Alabama; architects Merrick & Company of Greenwood Village, Colorado; steel fabricators North Alabama Fabricating Co. of Birmingham; and steel erectors LPR Construction of Loveland, Colorado.
Credits: NASA/MSFC/Emmett Given
Engineer Tara Marshall, left, talks about the installation of a pressurization control panel at Test Stand 4693 with Mike Nichols, lead test engineer for the Space Launch System liquid hydrogen tank structural test article. Over the coming weeks, engineers are installing networks of cables, pipes, valves, control systems, cameras, lighting and special equipment to prepare for testing. When the test article arrives, a total of 38 hydraulic cylinders will be positioned at points on the tank, pushing and pulling to simulate the forces experienced in launch and flight. At the base of the stand, 24 of the largest cylinders -- 3,200 pounds each, about as heavy as a medium-sized car -- will simulate the thrust produced by the RS-25 engines.
Credits: NASA/MSFC/Emmett Given
Major construction is complete on NASA’s largest new Space Launch Systemstructural test stand, and engineers are now installing equipment needed to test the rocket’s biggest fuel tank. The stand is critical for ensuring SLS’s liquid hydrogen tank can withstand the extreme forces of launch and ascent on its first flight, and later on the second flight, which will carry up to four astronauts in the Orion spacecraft on a journey around the moon, into the deep-space proving ground for the technology needed for the journey to Mars.
"There is no other facility that can handle something as big as the SLS hydrogen tank," said Sam Stephens, an SLS engineer working on the tests at NASA’s Marshall Space Flight Center in Huntsville, Alabama. "There are few places in the world like NASA’s Michoud Assembly Facility that could build these things, and even fewer that can test them."
After the project began in May 2014, Test Stand 4693 changed the skyline of Marshall as its twin towers soared to 221 feet (67.4 meters). In December, contractors and steelworkers handed the stand over to Marshall engineers, who are now busy installing complex networks of cables, pipes, valves, control systems, cameras, lighting and specially designed test equipment.
“The scale and capability of this test stand are unique, and creating it has taken people from across the country, from all walks of life -- concrete suppliers and finishers, steel fabricators and erectors, bolt manufacturers and more," said Robert Bobo, who manages SLS structural strength testing at Marshall. "Everyone who's touching this is proud of the Space Launch System, an American rocket that will send astronauts farther in space than humans have ever traveled before."
The stand will simulate the powerful dynamics of launch and flight by pushing, pulling and bending the SLS liquid hydrogen qualification test article, recently constructed by Boeing at NASA’s Michoud Assembly Facility in New Orleans. The 149-foot-long (45.4 meters) test article consists of a liquid hydrogen tank and equipment attached at each end to simulate the other parts of the 212-foot-long (64.6 meters) core stage, the backbone of the rocket. Together, the SLS liquid hydrogen and liquid oxygen tanks will feed 733,000 gallons (nearly 3 million liters) of super-cooled propellant to four RS-25 engines, producing a total of 2 million pounds of thrust at the base of the core stage.
The liquid hydrogen tank test article will travel by barge from Michoud to Marshall. When testing begins, the tank test article will be positioned between the towers, suspended beneath a crosshead. A total of 38 hydraulic cylinders or “loadlines,” each weighing from 500 to 3,200 pounds (approximately 230 to 1,500 kilograms), will be individually calibrated, outfitted with custom-built test cells to send and receive instructions and data, and then positioned at points all along the tank. At the base, 24 of the largest cylinders -- 3,200 pounds each, about as heavy as a medium-sized car -- will simulate the thrust produced by the RS-25 engines.
During testing, the cylinders extend and retract, pushing and pulling in different combinations against the test article, the test stand base and towers, applying millions of pounds of pulling and crushing force and up to 340,000 pounds (approximately 1.5 million newtons) of shearing or sideways force. During 30 or more test scenarios, instrumentation will capture more t