On this day in 1996, the Mars Global Surveyor mission was launched by NASA. It was an orbiter, and transmitted data on Mars’ composition, gravity, magnetic field, topography and weather patterns. Among other things, it discovered the mineral hematite (a type of iron ore) on Mars, which usually forms in the presence of water. The later missions of the rovers Spirit and Opportunity would search for and find hematite near their landing sites. It survived until November 2006, when a mishap caused it to lose power, and silenced it forever.