Voyager 1 & 2

Voyager 1 and Voyager 2 are twin spacecraft launched by NASA in 1977 to conduct a "Grand Tour" of the outer solar system, exploiting a rare planetary alignment that occurs once every 176 years. Together they transformed our understanding of Jupiter, Saturn, Uranus, and Neptune before continuing outward to become the first human-made objects to reach interstellar space.

Voyager 1 is now the most distant human-made object, approximately 24.8 billion km from Earth (as of 2026). At that distance, radio signals travelling at the speed of light take over 23 hours to reach it. Voyager 2 is slightly closer at approximately 20.8 billion km. Both spacecraft continue to transmit data using their 23-watt radio transmitters — less power than a refrigerator light bulb.

Each Voyager carries a Golden Record — a 12-inch gold-plated copper disc containing sounds and images selected to portray the diversity of life and culture on Earth, including greetings in 55 languages, music from Bach to Chuck Berry, natural sounds, and 116 encoded photographs. The records are intended as a message to any extraterrestrial civilisation that might encounter the spacecraft millions of years from now.

Both spacecraft are powered by radioisotope thermoelectric generators (RTGs) using plutonium-238, which produce electricity from radioactive decay. Power output decreases by about 4 watts per year, and NASA has been progressively shutting down instruments to conserve energy. Current projections suggest the Voyagers will continue transmitting data until approximately 2030.