Tag Archives: Space Launch System

Full-Duration Test

Aerojet Rocketdyne announced on August 13 that it successfully completed a full duration (535 seconds) verification test of its RS-25 rocket engine that will power NASA’s Space Launch System (SLS), America’s next generation heavy-lift launch vehicle. A test, conducted at NASA’s Stennis Space Center, was the sixth test in a seven-test series that began in January 2015 to validate the engine for use on the SLS.

NASA conducted a developmental test firing of the RS-25 rocket engine, on August 13 at the agency’s Stennis Space Center in Mississippi
NASA conducted a developmental test firing of the RS-25 rocket engine, on August 13 at the agency’s Stennis Space Center in Mississippi

«It is great to see this revered engine back in action and progressing full steam ahead for launch aboard Exploration Mission-1 in 2018», said Julie Van Kleeck, vice president of Aerojet Rocketdyne’s Advanced Space & Launch Programs business unit. «The RS-25 is the world’s most reliable and thoroughly tested large liquid-fueled rocket engine ever built».

The RS-25, previously known as the Space Shuttle Main Engine (SSME), successfully powered the space shuttle during 30 years of operation. The RS-25 uses a staged-combustion engine cycle that burns liquid hydrogen and liquid oxygen propellants to achieve performance never previously attained in a production rocket engine. Interestingly, the only exhaust produced by the RS-25 is water vapor in the form of steam.

The RS-25 will continue to serve the nation’s human exploration propulsion needs as the core stage engines for SLS. The SLS program has 16 engines in inventory at Aerojet Rocketdyne’s facility within Stennis Space Center, with 14 of them previously flown aboard the space shuttle.

«The engine that was tested on August 13, development engine 0525, continues demonstration of the new controller’s functionality and the engine’s ability to perform to SLS requirements», said Jim Paulsen, vice president, Program Execution, Advanced Space & Launch Programs at Aerojet Rocketdyne. «We are conducting engine testing to ensure all 16 flight engines in our inventory meet flightworthiness requirements for SLS».

SLS will fly 4 RS-25 engines at the bottom of the core stage as opposed to three that flew on the space shuttle; the solid rocket boosters will be closer to the RS-25 engines than they were on the shuttle stack; and the taller SLS launch vehicle will result in higher propellant inlet pressure on the engine system. These changes, as well as operating them at 109% thrust means the engines will need to withstand more demanding conditions than when they were previously flown.

In addition to preparing for the new environmental conditions, the engines also are receiving a technology «refresh» of their controllers, which serve as the brains of the engines. The upgraded controller provides for communication between the vehicle and the engine, relaying commands to the engine and transmitting data back to the vehicle to regulate the thrust and fuel mixture ratio and monitor the engine’s health and status.

«The new controller provides modern electronics, architecture and software», said Paulsen. «It will improve reliability and safety for the SLS crew as well as the ability to readily procure electronics for decades to come».

The first flight test of the SLS will be configured for a 70-metric-ton lift capacity and carry an un-crewed Orion spacecraft. As SLS evolves, it will be the most powerful rocket ever built and provide an unprecedented lift capability of 130 metric tons.

«SLS is the vehicle that will take astronauts to Mars and pre-position cargo for their survival», said Van Kleeck. «It is great to see that the red planet is one step closer and know our Aerojet Rocketdyne team is helping make that dream a reality».



Test Fire

The solid rocket booster that will propel NASA’s skyscraper-size Space Launch System (SLS) rocket and its Orion spacecraft on deep space missions in the coming years took a huge step forward in its development on March 11, 2015, unleashing its fury on a barren mountainside at Orbital ATK’s test stand in Promontory, Utah, for the Qualification Motor-1 test fire (QM-1). The colossal 154-foot-long (47-meter-long) booster, the largest of its kind in the world, ignited to verify its performance at the highest end of the booster has accepted propellant temperature range, 90 degrees. That’s the temperature the SLS can expect to encounter on a regular basis at its Florida launch site on Kennedy Space Center (KSC) Launch Complex 39B, and this week NASA and Orbital ATK released initial findings and data from the QM-1 test fire. Detailed inspections of the disassembled booster will take another several months.

Orbital ATK’s SLS solid rocket booster Qualification Motor-1 test fire March 11, 2015 at the company’s test stand in Promontory, Utah (Photo Credit: Mike Killian/AmericaSpace)
Orbital ATK’s SLS solid rocket booster Qualification Motor-1 test fire March 11, 2015 at the company’s test stand in Promontory, Utah (Photo Credit: Mike Killian/AmericaSpace)

«Having analyzed the data from QM-1 for a little more than a month, we can now confirm the test was a resounding success», said Charlie Precourt, Vice President and General Manager of Orbital ATK’s Propulsion Systems Division, and four-time space shuttle astronaut. «These test results, along with the many other milestones being achieved across the program, show SLS is on track to preserve our nation’s leadership in space exploration».

It took only a second for the booster to reach 3.6 million pounds of thrust (equivalent to 22 million horsepower/16,405 MW), burning through 5.5 tons of propellant per second, at 5,000 degrees Fahrenheit, for just over two minutes – exactly as it will when it launches the SLS. More than 500 instrumentation channels were used to help evaluate over 100 defined test objectives, and newly designed avionics hardware and equipment to control the motor helped provide improved test monitoring capability.

According to Mike Killian, AmericaSpace reporter, the test also demonstrated the booster’s ability to meet applicable ballistic performance requirements, such as thrust and pressure. Other objectives included data gathering on vital motor upgrades, such as the new internal motor insulation and liner and an improved nozzle design. «Current data show the nozzle and insulation performed as expected, and ballistics performance parameters met allowable requirements», noted Orbital ATK in their report. «Additionally, the thrust vector control and avionics system provided the required command and control of the motor nozzle position».

The five-segment Solid Rocket Booster has been in development for years, having been initially designed to launch NASA’s Ares rockets for the agency’s cancelled Constellation program. The booster is similar to the four-segment Solid Rocket Boosters (SRBs) that helped launch NASA’s now retired space shuttle fleet, but it is even larger and incorporates several upgrades and improvements. Now, after a lengthy investigation and trouble-shooting effort to determine root causes and corrective actions for the existence of small voids previously discovered prior to QM-1 between the propellant and outer casing of the booster’s aft segment, Orbital ATK is back on track with the booster’s development and already constructing the hardware for a second test fire in spring 2016 (QM-2).

A cold-temperature test, at a target of 40 degrees Fahrenheit, the low end of the propellant temperature range, is planned for QM-2 before the hardware testing to support qualification of the boosters for flight will be complete, at which point Orbital ATK will then be ready to proceed toward the first flight of SLS, an uncrewed flight to validate the entire integrated system, currently scheduled to fly on the Exploration Mission-1 (EM-1) in late 2018.

Orbital ATK technicians inspect the SLS Qualification Motor-1 booster after a successful test fire on March 11, 2015 (Photo Credit: Orbital ATK)
Orbital ATK technicians inspect the SLS Qualification Motor-1 booster after a successful test fire on March 11, 2015 (Photo Credit: Orbital ATK)

With QM-1 there have now been four fully developed, five-segment SRBs fired up on Orbital ATK’s Promontory, Utah, T-97 test stand since 2009, with the most recent prior to QM-1 having been conducted in 2011, and all performed fine. The first three tests, known as the Development Motor test series (DM-1, DM-2, and DM-3), helped engineers measure the new SRB’s performance at low temperature, verify design requirements of new materials in the motor joints, and gather performance data about upgrades made to the booster since the space shuttle program.

The five-segment SLS boosters will burn for the same amount of time as the old shuttle boosters – two minutes – but they will provide 20 percent more power, while also providing more than 75 percent of the thrust needed for the rocket to escape the gravitational pull of the Earth.

«Ground tests are very important – we strongly believe in testing before flight to ensure lessons-learned occur on the ground and not during a mission», added Precourt. «With each test we have learned things that enable us to modify the configuration to best meet the needs for the upcoming first flight».

Although the boosters themselves will provide 75 percent of the power needed to break Earth’s hold, the SLS will still employ four engines of its own – former (upgraded) liquid-fueled space shuttle RS-25 engines – which are currently at NASA’s Stennis Space Center preparing for their own series of tests, the first of which occurred earlier this year. A second RS-25 test fire is currently scheduled for May or June this year.

The SLS program also kicked off its Critical Design Review (CDR) this week at NASA’s Marshall Space Flight Center in Huntsville, Alabama, which demonstrates that the SLS design meets all system requirements with acceptable risk, and accomplishes that within cost and schedule constraints. The CDR proves that the rocket should continue with full-scale production, assembly, integration, and testing, and that the program is ready to begin the next major review covering design certification. The SLS CDR is expected to be completed by late July.