LOS ANGELES -- Converting English measurements into metric units isn't exactly rocket science, but NASA is blaming the loss of its $125 million Mars Climate Orbiter on a metric mishap.
The monumental goof caused the spacecraft to fly too close the Red Planet and burn up or break apart in the atmosphere it was to have studied, the space agency said Thursday.The probe had successfully flown 416 million miles in 91/2 months before vanishing just as it was starting to circle Mars early on Sept. 23.
"It does not make us feel good that this happened," said Tom Gavin of NASA's Jet Propulsion Laboratory. "This mix-up has caused us to look at our entire end-to-end process. We will get to the bottom of this."
A final report on the mission is expected by Nov. 19 -- enough time to fix any problems with another Mars-bound spacecraft that is scheduled to land in early December.
In a preliminary report, JPL said the spacecraft's builder, Lockheed Martin Astronautics, submitted acceleration data in English units of pounds of force instead of the metric unit called newtons. At JPL, the numbers were entered into a computer that assumed metric measurements.
"In our previous Mars missions, we have always used metric," Gavin said.
Noel Hinners, vice president of flight systems for Lockheed Martin Astronautics in Denver, admitted the numbers should have been submitted in metric units. Lockheed officials are reviewing contracts to see whether NASA specified units of measurement.
The bad numbers had been used since the spacecraft's launch last December, but the effect was so small that it went unnoticed. The difference added up over the months as the spacecraft journeyed toward Mars.
Mission navigators crunched the numbers to help understand the position of the spacecraft during flight. The calculations measured the force of small thruster firings that helped counteract the effects of natural forces such as the solar wind -- energy particles streaming from the sun.
NASA and outside experts will investigate the mechanisms that should have caught the discrepancy in numbers, said Edward Weiler, NASA's associate administrator of space science.
"The problem here was not the error, it was the failure of . . . the checks and balances in our processes to detect the error," he said.
The blunder is not expected to affect NASA's relationship with Lockheed, which has built several probes for the space agency, including the Magellan probe to Venus and the Mars Global Surveyor.
"This country has not gone 100 percent metric," said Chris Jones, program manager for JPL's Mars Surveyor Program. "(Companies) continue to use the English system of units, and that's something we have dealt with effectively on other programs."