NASA Lost A $125M Spacecraft Over Pounds
In 1999, NASA lost the $125M Mars Climate Orbiter because one team's software used pounds and the other's used newtons.
The script
One team used pounds. The other used newtons... and a spacecraft was lost at Mars.
In nineteen ninety-eight, NASA launched the Mars Climate Orbiter.
You see, the software that planned its thruster pushes measured them in pounds.
But the navigation software read those numbers as newtons.
A pound is about four and a half newtons... so EVERY push was bigger than the map thought.
For nine months, the error quietly added up.
It came in about fifty-seven kilometers above Mars... and was never heard from again.
A hundred and twenty-five million dollars, gone... because
The facts, checked
- The Mars Climate Orbiter launched on 11 December 1998. It was lost on 23 September 1999 during Mars orbit insertion, after passing behind the planet.
- Lockheed Martin's ground software reported thruster impulse in pound-force seconds, but JPL's navigation software expected newton-seconds. The thrusters' effect was underestimated by a factor of 4.45, since 1 lbf = 4.45 N.
- The spacecraft came within about 57 km of the surface, too low to survive, and most likely broke up in the atmosphere.
- About $125 million for the spacecraft (the whole mission was about $327 million).
