Ian Whittingham, PMP is director of Calixo Consulting, providing project and program management expertise from initiation through to implementation, covering business transformation, workflow process re-engineering, and enterprise data integration. He is a regular contributor to ProjectManagement.com. You may contact Ian directly at [email protected].
On September 23, 1999 radio contact with NASA’s Mars Climate Orbiter was lost as the space probe passed behind the red planet. It was scheduled to reappear 20 minutes later, but it never did. A little over two months later on December 3, the Orbiter’s sibling--the Mars Polar Lander--fired its thruster rocket as it prepared to enter the upper Martian atmosphere and begin a controlled descent onto the polar landscape below. But NASA never received confirmation that the rocket had fired correctly, and no radio signal was ever received again from the Polar Lander.
Instead of entering an elliptical orbit of some 150 kilometers above the Martian surface--where the probe would have collected survey data transmitted by the Polar Lander below--it has been conjectured that the ClimateOrbiter’s altitude dropped to around 57 kilometers, when it hit the Martian atmosphere and consequently broke apart. Initial investigation into the accident focused on a critical mismatch in the units of measurement used to operate and control the space probe’s trajectory during its mission.
NASA’s trajectory models were based on the Newton unit of measurement (defined as the force required to accelerate one kilogram of mass at a rate of one meter per second per second). But the Orbiter’s sub-contractor (Lockheed Martin) had used the Imperial unit