MEDIA RELATIONS OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011 http://www.jpl.nasa.gov Mars Climate Orbiter Launch Status December 9, 1998 A review of Mars Climate Orbiter software designed to protect against hardware failures on the spacecraft has uncovered a flaw that project engineers decided to fix before launch. The problem involves a device called a charge control unit, which regulates the flow of charge from the spacecraft's solar arrays to the battery. If the primary charge control unit were to fail during the mission, the battery could be overcharged and fail before the spacecraft's fault protection software was able to detect the error and command a swap to the backup charge control unit. "The fix is relatively simple, but we want to be sure we execute a prudent test program that insures that we have actually fixed the problem without creating additional unforeseen problems," said Dr. John McNamee, Mars Climate Orbiter project manager at NASA's Jet Propulsion Laboratory, Pasadena, CA. "We have the benefit of using the Mars Polar Lander spacecraft as a testbed to make sure we have accomplished what we intended to accomplish." Engineers believe the test program will take between 24 and 48 hours to implement, clearing the way for a launch attempt on Friday, December 11, or Saturday, December 12. On Friday there are two nearly instantaneous launch opportunities at 1:45 p.m. and 2:52 p.m. Eastern Standard Time (EST). On Saturday the launch opportunities are at 1:34 p.m. and 2:40 p.m. EST. Launch of the orbiter's sibling spacecraft, Mars Polar Lander carrying the Deep Space 2 microprobes, remains on schedule for launch January 3, 1999.

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