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The Importance of Ground Testing Flight Systems
Safely propelling a spacecraft to its orbital destination is highly complex and requires great skill, planning and precision. Testing flight systems on the ground prior to launch is of utmost importance because of the lives involved and the valuable shuttle cargo.
Stennis Space Center’s principal mission for NASA is to support the development and acceptance testing of large propulsion systems for the Space Shuttle, New Launch System (NLS) and the Advanced Solid Rocket Motor (ASRM) programs.
Prior to launch, every shuttle main engine requires acceptance testing at SSC. The task of firing the engines is accomplished by securing them individually in one of SSC’s three concrete and steel test stands where a series of firings are performed before they are installed on the orbiter. During these tests, the engines are “hot fired” for various periods of time under different operating conditions to determine their flight worthiness.
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A Space Shuttle Main Engine undergoes a static firing on the B-l test stand.
The data accumulated from these ground tests, which simulate flight profiles, are analyzed to ensure that engine performance is acceptable and that the required thrust will be delivered in the critical ascent phase of shuttle flights. In the process, NASA is able to verify design changes, develop components and resolve any problems in the engines before they are put in the actual flight situation.
Also, SSC has facilities dedicated soley to the research and development of rocket plume spectrometry instrumentation and applications. Researchers at the Diagnostics Testbed Facility simulate and analyze emissions in the rocket exhaust plume from scale engines to develop the knowledge base and understanding to detect potential problems in Space Shuttle Main Engines.
SSC’s sprawling test complex contains three massive test stands that house the main engines during their firings. The A-l and A-2 stands, each 154 feet tall, are used to test the engines individually. The 265-foot dual stand contains the B-l position for single-engine tests and the B-2 position once used to test the Saturn V booster stage, as well as the Space Shuttle’s main propulsion system.
The stands are linked by a 7V2-mile manmade canal system used for transporting large rocket stages and propellants. Other significant features of the test complex are control centers, data acquisition facilities, a large high-pressure gas complex, a high-pressure water facility served by a 64 million gallon reservoir, an electrical power generation plant, and engineering and administrative offices.
SSC’s roles in testing are expanding into the field of turbomachinery technology development for the unmanned New Launch System and future generations of space vehicles. The NLS, targeted for operation in the 1990s, will be used to carry heavier payloads more cost effectively than previous systems. Construction of a Component Test Facility is under way to allow NASA to determine the operational limits of critical components before they are assembled into the engine system. In this way, problems can be driven out at the component level rather than waiting until they are all combined into an engine to test them.
In addition, Stennis has plans to begin full-scale ground testing of the Advanced Solid Rocket Motor in 1994. New test facilities will be built to verify the motor’s design of clean propellants, ignition systems, ground support equipment and launch procedures. With the onset of the ASRM program, SSC will have sole responsibility for testing the Space Shuttle’s entire propulsion system.