MCO_Oberg - Why the Mars Probe Went Off Course - James Oberg

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Why the Mars Probe Went Off Course -- James Oberg http://www.jamesoberg.com/mars/loss.html 1 of 11 1/10/05 4:04 PM Why The Mars Probe Went Off Course By James Oberg SPECTRUM Magazine December 1999 AIRCRAFT ACCIDENT INVESTIGATORS have a special term for a particularly insidious type of accident--CFIT, or controlled flight into terrain. It occurs when human error in the cockpit, in the traffic control tower, or in the flight planning process in effect flies a perfectly good airplane right into the ground. In the past 40 years, space flight has encountered all sorts of failure modes. Propulsion systems have leaked and exploded. Power systems have short-circuited. Observation instruments have failed to work or have been pointed in wrong directions. But until this year no CFIT had occurred in outer space. Then, on 23 September, through a series of still-baffling errors, flight controllers at the Jet Propulsion Laboratory, a California Institute of Technology facility under contract to NASA, sent erroneous steering commands to the Mars Climate Orbiter as it neared the target planet. Obeying blindly like all true robots, the probe, metaphorically speaking, marched off the cliff and was destroyed. NASA assigned three separate teams to investigate the embarrassing, US $125 million debacle and determine its cause. Preliminary public statements faulted a slip-up between the probe's builders and its operators, a failure to convert the English units of measurement used in construction into the metric units used for operation. After six weeks, on 10 November, NASA officials released their preliminary findings. However, an IEEE Spectrum investigation had been going on separately, using unofficial sources associated with the program and independent experts. Spectrum quickly learned that far more had gone wrong than just a units conversion error. A critical flaw was a program management grown too confident and too careless, even to the point of missing opportunities to avoid the disaster. As reconstructed by Spectrum, ground controllers ignored a string of indications that something was seriously wrong with the craft's trajectory, over a period of weeks if not months. But managers demanded that worriers and doubters "prove something was wrong," even though classic and fundamental principles of mission safety should have demanded that they themselves, in the presence of significant doubts, properly "prove all is right" with the flight. As a result, the probe was about 100 kilometers off course at the end of its 500-million-kilometer voyage--more than enough to accidentally hit the planet's atmosphere and be destroyed. Edward Stone, director of the Jet Propulsion Laboratory (JPL), in Pasadena, Calif., did not try to dodge responsibility for events. "Our inability to recognize and correct this simple error has had major implications," he stated in a 24 September press release from the lab.
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Why the Mars Probe Went Off Course -- James Oberg http://www.jamesoberg.com/mars/loss.html
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MCO_Oberg - Why the Mars Probe Went Off Course - James Oberg

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