Jonas Di–o 		      June 17, 2002
NASA Ames Research Center, Moffett Field, Calif.
Phone:  650/604-5612 or 604-9000
E-mail: jdino@mail.arc.nasa.gov

Shari Phillips
Honeywell Space Systems, Phoenix, AZ.
(602) 822-3746
E-mail: shari.phillips@honeywell.com

RELEASE: 02-71AR

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 known collectively as 
Integrated Vehicle Health Management (IVHM). 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 looked at 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 realism, NASA Ames and Honeywell collaborated to develop 
scenarios and select component technologies that will 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 
provided 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's Marshall Space Flight Center in Huntsville, Ala., leads the Space 
Launch Initiative for NASA's Office of Aerospace Technology.

Information about Integrated Vehicle Health Management and NASA's Space 
Launch Initiative can be found on the Internet at:

http://www.slinews.com

http://www.spacetransporation.com

Information about Honeywell can be found on the Internet at:

http://www.honeywell.com

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