12Mar/090
Everyone makes mistakes
Even NASA. Here are two mission failures.
September 1999: In the first, NASA lost a $125 million spacecraft called Mars Climate Orbiter because of confusion between metric units and English units. While the spacecraft was built in one system, the communication was expected in another. After completing a nearly 10-month journey to Mars, the Orbiter was suddenly lost. Next time, you can’t convert currency or temperature, you can tell yourself it's rocket science! More here.
December 1999: In the second, the Mars Polar Lander crashed because it turned off its engines when it was still 40 m above the Martian surface (thinking it had landed). More here.