The first images brought back were mostly haze, a disappointment to those who hoped to settle the debate on Martian life, but the Mariner 4 nevertheless provided an invaluable glimpse of Earth’s closest neighbor. For the better part of 70 years, since a mistranslation of an Italian astronomer’s work brought up the idea of water on Mars, scientists wrestled hopes and dreams of life on the red planet against the increasing likelihood of no such life existing. Mariner 4 was the first to study the planet up close and begin to bring back answers.

On this day, November 28, in 1964, the Mariner 4 spacecraft launched to Mars. In July of the following year it went into orbit around Mars and began beaming back data.

Readings showed a surface pockmarked by craters, with a chilly -100 degrees celsius (-148 degrees Farenheit) during the day. If intelligent life did exist there, it was unlike any kind of intelligent life on Earth. Aliens believers switched from talking about Martians to talking about life on planets around distant suns.