Why Are Units So Important

Mars Climate Orbiter, which was intended to be the Red Planet s first weather satellite. After a 416-million-mile (mi) journey, the spacecraft was supposed to go into Mars s orbit on September 23, 1999. Instead, it entered Mars s atmosphere about 100 km (62 mi) lower than planned and was destroyed by heat. Mission controllers later determined that the spacecraft was lost because English measurement units were not converted to metric units in the navigation software. 

Engineers at Lockheed Martin Corporation, who built the spacecraft, specified its thrast in pounds, which is an English unit of force. Scientists at NASA s Jet Propulsion Laboratory, on the other hand, who were responsible for deployment, had assumed that the thrust data they were given were expressed in newtons, a metric unit. To carry out the conversion between pound and new- 

Conunenting on the failure of the Mars mission, one scientist said, This is going to be the cautionary tale that will be embedded into introduction to the metric system in elementary school, high school, and college science courses till the end of time.  

Mars Climate Orbiter during preflight tests. 

Substances are identified by their properties as well as by their compositiom Properties of a substance may be quantitative (measitred and expressed with a mtmber) or qualitative (not requiring explicit measirrement). 

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