Wednesday, May 7, 2014

NASA completes ‘cold-shock’ tests for SLS engine

     Engineers working at NASA’s Stennis Space Center (SSC) in Mississippi have successfully completed a cold-shock test on structural piping for the facility’s newly renovated A-1 Test Stand on May 1. This is a critical project milestone leading up to scheduled testing of the RS-25 rocket engine that is planned for use on NASA’s new heavy-lift booster – the Space Launch System (SLS).

     “This is a very exciting time at NASA,” said Gary Benton, RS-25 rocket engine test project manager, in a statement released by NASA. “We are moving closer and closer to making unprecedented space exploration missions a reality.”

(Click above to watch NASA video)

     The liquid fuels that power this engine will be pumped through a complex system of pipes at extremely cold temperatures. The RS-25 engine generates thrust by combining liquid oxygen around -300 degrees Fahrenheit, with liquid hydrogen colder than -400 degrees Fahrenheit. NASA engineers “cold-shock” tested the piping system by monitoring the effects of liquid nitrogen flowing through the piping at -320 degrees Fahrenheit.

     “We’re pleased with how the “cold shock” tests of the modified Liquid Hydrogen (LH2) and Liquid Oxygen (LOX) piping systems at Stennis turned out. All of this is leading toward the testing of the RS-25. To that end, the AR test article team has been steadily finalizing drawings, specifications, and planning documents that will be used to install, checkout, test and process the engine for the first test scheduled in July,” said Jack Fabre, RS-25 Test Article Integration at Aerojet Rocketdyne.

     The piping system must be built to handle extreme cold and hot temperatures that shift as much as 500 degrees during final “hotfire” testing. To allow for this change, the piping is designed to move as it expands and contracts, with data being evaluated along the way to ensure project safety while looking for any needed adjustments.

     Modifications to this testing facility have been ongoing since last fall, which involved the installation of new equipment and components to prepare for the RS-25 engine. The first RS-25 engine to be tested at the A-1 Test Stand is scheduled for delivery by early summer.

     “A test like this may sound benign since no flammable propellant is used, but it is very significant to make sure we have the proper piping design and setup for engine testing,” said Jeff Henderson, A-1 Test Stand director, in a statement released by NASA.

     Along with the cold-shock testing came calibrations on a new thrust measurement system (TMS), which will be used to obtain accurate engine thrust information, and performing checks on the liquid oxygen tank and vent system. More components for the TMS still need to be installed before testing can begin on the soon-to-be-delivered and installed RS-25 engine.

     The RS-25 engine comes with an integrated computer known as the Main Engine Controller (MEC), which regulates the functions of the combustion system and monitors its performance. Not only does this control the valves that flow the liquid propellant, but also keeps track of vital systems during the startup ignition, firing, and shutdown sequences. Engineers at Stennis will collect data during all of these key phases, and ensure not only system power but also reliability.

     Reliability is a big part of the RS-25 engine’s past, with its long use as the Space Shuttle Main Engine (SSME) starting with the very first space shuttle flight STS-1 on April 12, 1981. Several upgrades were made to improve efficiency during its 30 years with the Space Shuttle program, with former manufacture Pratt & Whitney Rocketdyne reporting a 99.95 percent reliability rate. Pratt & Whitney Rocketdyne merged with Aerojet last year to form Aerojet Rocketdyne based in Sacramento, California, a new company leading the future development of RS-25 engines along with other engine products.

     The eventual goal of the RS-25 rocket engine will be to power the core stage of NASA’s new Space Launch System (SLS) heavy-lift booster. SLS is the primary launch vehicle that makes up the new exploration mission for NASA, with planned missions beyond low-Earth Orbit (LEO) that include studying a captured near-Earth asteroid (which will be towed into lunar orbit) and eventually, one day, landing on and exploring the planet Mars.

     The first launch of SLS is planned for late 2017, so long as testing and development phases continue to run as planned. This will be an unmanned flight. In 2021, NASA plans a crewed flight of the massive rocket. In the intervening years NASA will test out and validate a number of systems relating to the rocket.

By James Tutten

(Above photo provided by NASA)

(Published at on May 7, 2014.)

A-1 Test Stand Operations team member during cold-shock test. Photo Credit: NASA

RS-25's await trasport at Kennedy Space Center to Stennis in 2011. Photo Credit: Jason Rhian / SpaceFlight Insider.


Post a Comment

Twitter Delicious Facebook Digg Stumbleupon Favorites More