Carl Sagan was an astronomer, astrophysicist, and cosmologist, deeply committed to scientific outreach.
It was his passion, and he managed to convey it in every task he undertook.
His involvement with the US space program began early on, as he worked as an advisor to NASA since the 1950s.
In addition to instructing astronauts and preparing experiments, he was also responsible for the so-called "Golden Record" on the Voyager spacecraft, a universal message containing Earth's content and directed towards possible extraterrestrial life, which was sent out of the solar system with the Voyager spacecraft in 1977.