On April 5, 1973, NASA launched the Pioneer 11 mission into the outer solar system. Pioneer 11 would become the first spacecraft to fly by Saturn, and it flew by Jupiter and the asteroid belt along the way. It launched about a month after its twin, Pioneer 10. Both spacecraft brought along gold plaques with pictures and messages pertaining to Earth, just in case they encountered any extraterrestrials out in space. The plaques include drawings of naked humans and some symbols and diagrams that explain where the spacecraft came from. Seventeen years after it launched, it became the fourth spacecraft to leave planetary part of the solar system when it flew past Neptune. Pioneer 11 is now on its way toward interstellar space.