"PathFinder runs the program under test through a lot of trials, and tries to find a test that will cause the program to fail," Penix observed.

The Java Pathfinder work "is part of an effort to develop tools and methods to identify and eliminate software errors in NASA's increasingly complex and mission-critical software systems," according to David Korsmeyer, who leads the NASA Ames Intelligent Systems Division.

"Java Pathfinder was used to detect inconsistencies in the executive software for the K9 Rover at NASA Ames," Korsmeyer said. The K9 rover is a six-wheeled, solar-powered rover developed jointly at NASA Ames and NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif.

In addition, computer scientists used elements of Java Pathfinder to develop verification computer code for Livingstone 2 software, a diagnosis system now flying on the EO-1 spacecraft "and an example of the kind of autonomy software that will be crucial to future NASA missions," Korsmeyer said.

"We're continuing to develop software-testing technologies," said Penix. "NASA has a lot of software, and it is difficult to get it right; so we want to take advantage of all the work that is going on out there and incorporate it into our tools," he explained.

According to scientists, if PathFinder finds an error in a Java application, the software checker reports the whole process that leads to the bug. Unlike a normal debugger, Java Pathfinder keeps track of every step the software checker takes to find a defect, Penix noted.

"PathFinder already has been enhanced and tested by several universities and companies," Penix said. "Now, additional universities can add more features to PathFinder," he said, describing how providing Java Pathfinder to the computing world could benefit NASA. Pathfinder is in its sixth year of active development.

NASA Ames scientists are offering Java PathFinder via SourceForge.net: http://javapathfinder.sourceforge.net/