Volume 10, Number 4 • July/August 2002 • Aerospace Technology Development

Diagnostic Software to Keep Launch Vehicles Healthy

As launch vehicles become more and more complex, ensuring crew safety and mission success becomes increasingly difficult, but, according to a recent technologies demonstration, help is on the way.

Identifying minor system errors before they become critical is one key to developing safer, more reliable and less expensive space vehicles. As part of NASA’s Space Launch Initiative (SLI), Honeywell, Phoenix and NASA Ames Research Center, located in California’s Silicon Valley, recently demonstrated a suite of advanced diagnostic tools for NASA’s Integrated Vehicle Health Management (IVHM) program. The milestone demonstration showed that separate technologies could be integrated into a cohesive package that can handle realistic problem scenarios that might be encountered in space.

“The Space Launch Initiative develops critical technologies, but it also demonstrates the value of those technologies in a relevant environment. Early demonstrations such as this are part of making sure we are on the right track,” said William Kahle, IVHM project manager at NASA Ames.

For the demonstration, realism was a must, so engineers investigated various types of failures. Along with key subsystem failures, cross-subsystem “sympathetic” failures were tested. “Sympathetic” failures occur when problems in one system affect the performance in an unrelated system. To handle these types of failures and to build system flexibility, the engineers used a variety of techniques.

“We recognized early on that the health management requirements of RLVs [reusable launch vehicles] demand a range of diagnostic approaches from model-based to expert system technologies,” said Ronald Quinn, principal investigator for Honeywell.

To ensure this realism, NASA Ames and Honeywell collaborated to develop scenarios and select component technologies that would provide relevant and significant results for the next generation of RLVs. In one scenario, the IVHM systems were able to determine that an indicated pressure system failure in a propulsion subsystem actually was caused by a failure in a power system control module.

“This is a realistic scenario that occurs often in complex systems such as RLVs,” said Dr. Ann Patterson-Hine of NASA Ames. “It demonstrates the need for a vehicle-wide health management system.”

NASA Ames, which leads the IVHM effort for the agency’s Space Launch Initiative, also has developed other diagnostic and simulation tools. Livingstone, a model-based reasoner, was selected to emulate the propulsion health management system while TEAMS (Testability Engineering and Maintenance System), a product of Ames’ Small Business Innovative Research program, provided model-based reasoning for the power system and vehicle level diagnoses. Spacecraft Control Language was used to develop expert systems and the architectural infrastructure that integrated these technologies. They cover a wide range of capabilities necessary to satisfy the health-management needs for RLVs.

The Space Launch Initiative is NASA’s technology research and development program aimed at dramatically increasing safety and reliability, and reducing the cost of a second-generation reusable launch vehicle. All NASA field centers and the Air Force Research Laboratory are actively participating in the Space Launch Initiative and are vital to its success. NASA Marshall Space Flight Center, in Huntsville, AL, leads the Space Launch Initiative for NASA’s Office of Aerospace Technology. Q

For more information, contact Jonas Diño at NASA Ames Research Center, phone: 650/604-5612, jdino@mail.arc.nasa.gov. Please mention you read about it in Innovation.

NASA Official: Jonathan Root • Web Design: Printing & Design Office, NASA Headquarters • Credits