Question

In 1999, the 125 million dollar Mars Climate Orbiter crashed onto the surface of Mars due to a unit conversion mistake. Briefly research this story and write a short, one or two paragraph, explanation of the unit conversion error that caused the crash (make sure you use your own words and include the list of references that you used). Then, show the unit conversion that the engineers providing the information to NASA’s Jet Propulsion Lab (JPL) should have used to ensure that the values were in the correct units.

Answer 1

The Mars Climate Orbiter (formerly the Mars Surveyor '98 Orbiter) was a 338-kilogram (745 lb) robotic space probe launched by NASA on December 11, 1998 to study the Martian climate, Martian atmosphere, and surface changes and to act as the communications relay in the Mars Surveyor '98 program for Mars Polar Lander.

However, on September 23, 1999, communication with the spacecraft was lost as the spacecraft went into orbital insertion, due to ground-based computer software which produced output in non-SI units of pound-force seconds (lbf·s) instead of the SI units of newton-seconds (N·s) specified in the contract between NASA and Lockheed. The spacecraft encountered Mars on a trajectory.The spacecraft encountered Mars on a trajectory that brought it too close to the planet, causing it to pass through the upper atmosphere and disintegrate.

So correct conversion should be 1lbf.s=0.046N.s that could have stop failure of mission.

sources:-

^[1] Stephenson, Arthur G.; LaPiana, Lia S.; Mulville, Daniel R.; Rutledge, Peter J.; Bauer, Frank H.; Folta, David; Dukeman, Greg A.; Sackheim, Robert; Norvig, Peter (November 10, 1999). Mars Climate Orbiter Mishap Investigation Board Phase I Report (PDF).NASA.

(2) "Metric mishap caused loss of NASA orbiter". CNN. September 30, 1999. Retrieved March 21, 2016.