Voyager 1 and 2: Humanitys Farthest Reaching Spacecraft

Launched in 1977, Voyager 1 and 2 remain humanitys most distant emissaries. Voyager 1, now over 24 billion kilometers from Earth in interstellar space, takes 22 hours for its radio signals to reach Earth at the speed of light. The twin spacecraft took advantage of a rare planetary alignment that occurs every 175 years, allowing a single mission to visit all four outer planets through gravitational slingshots. Voyager 2 remains the only spacecraft to have visited Uranus and Neptune, and many discoveries at these ice giants have not been followed up for nearly 40 years.

Each spacecraft carries a Golden Record: a 12-inch gold-plated copper disc containing sounds and images of Earth, from whale songs to Chuck Berry, greetings in 55 languages, and diagrams showing our location relative to pulsars. The records are designed to last a billion years. Both spacecraft are powered by radioisotope thermoelectric generators producing about 250 watts from decaying plutonium-238. Power is declining by about 4 watts per year, and instruments are being turned off one by one to conserve energy.

NASA projects the last instrument will fail around 2025-2030, after which the spacecraft will silently coast through the galaxy carrying their message from Earth..