December 16th

On Dec. 16, 1962, NASA launched the Explorer 16 spacecraft to study micrometeoroids near Earth. 

The mission would determine how likely it would be for spacecraft to get damaged by the small space rocks and dust particles around the Earth. The cylindrical spacecraft measured about 6 feet long and 2 feet in diameter. It carried instruments that could detect when meteoroids hit the spacecraft and assess the resulting damage. 

Data from this mission helped scientists determine the size, number, distribution, and momentum of dust particles in the near-earth environment.

Source: https://www.space.com/39251-on-this-day-in-space.html