"The problem is sometimes little things can really come back and make a big difference, and that's the case we have today."
-Arthur G. Stephenson, Director
|The Mars Climate Orbiter failed because the rules
were not followed. In most scientific calculations the
metric system is used. For the Mars Climate Orbiter, the Jet
Propulsion Laboratory (JPL), used the ground software
file, "Small Forces." Lockheed
Martin wrote the software program using U.S.
Customary units, when it should have been in metric
units. During the nine month trip from Earth to Mars, the
pressure on the Mars Climate Orbiter's solar array caused
the Orbiter to twist. To correct this, the Orbiter had to
be adjusted ten to fourteen times a week. Using the wrong
units in the corrections, put the Orbiter on the wrong
trajectory. The navigation team thought the Mars Climate
Orbiter was about 110 kilometers above the surface of
Mars. The closest the Orbiter could get to the Martian
surface without being destroyed was about 93 kilometers.
In reality, the Orbiter was only 57 kilometers above
Mars. That's a big difference in U.S. Customary or
metric! The Mars Climate Orbiter probably did not
|The solar array of the Mars Climate Orbiter from tip to tip is the same length as a fifteen passenger van. The van is also the same height and width as the Mars Climate Orbiter's main body. Imagine trying to control a van-sized spacecraft that is heading for Mars 255.2 million kilometers away!|
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