Voyager 1 is the most distant human-made object, and along with Voyager 2, is exploring where nothing from Earth has flown before. Launched by NASA in 1977 to explore the outer planets, both probes have crossed into interstellar space. They continue to send back scientific data from beyond the edge of the Sun’s magnetic influence.

Reaching interstellar space

NASA launched Voyager 2 on Aug. 20, 1977, and Voyager 1 on Sept. 5, 1977. Their primary mission was to explore Jupiter and Saturn. After making discoveries at those planets, the mission was extended.

Voyager 2 went on to explore Uranus and Neptune. The Voyager Interstellar Mission was designed to explore the outermost edge of the Sun’s domain and beyond. Voyager 1 entered interstellar space in August 2012, becoming the first human-made object to do so. Voyager 2 followed, entering interstellar space on Nov. 5, 2018.

This area between stars is filled with material ejected by the death of nearby stars millions of years ago. As of Aug. 21, 2024, Voyager 1 was 164.7 astronomical units from Earth, according to NASA. One astronomical unit is the distance from Earth to the Sun, which is about 93 million miles. Voyager 1 is escaping the solar system at roughly 3.5 astronomical units a year, while Voyager 2 is moving at about 3.1 astronomical units per year.

How NASA communicates with the probes

Both spacecraft send scientific information about their surroundings through NASA’s Deep Space Network. The computers on the Voyager probes process about 8,000 instructions a second. A modern smartphone yields more than 14 billion instructions per second, according to NASA.

The spacecraft operate on radioisotope thermoelectric generators. This power source produces four watts less each year, according to NASA. Because of this diminishing electrical power, the Voyager team has to prioritize which instruments stay on and which are turned off.

Conserving power to stay in contact

To keep the spacecraft functioning, engineers turn off heaters and other systems one by one as part of power management. They prioritize operating the fields and particles instruments, which are the most likely to send back key data about the heliosphere and interstellar space.

The cameras on both spacecraft were turned off after Voyager 1 took its final image in 1990 to save power and memory for other instruments. Mission managers also removed the software from both spacecraft that controls the cameras. The computers on Earth that understand the camera software no longer exist.

Even when the probes can no longer collect science data, engineering data could continue to be returned for several more years. The two spacecraft could remain in range of the Deep Space Network through about 2036. This depends on how much power the spacecraft still have to transmit a signal back to Earth.

The Golden Record

Each Voyager spacecraft carries a 12-inch gold-plated copper disk designed as a greeting to any form of life that might be encountered. The Voyager Golden Record holds sounds and images selected to portray the diversity of life and culture on Earth. The cover includes inscribed symbols that show the location of Earth relative to several pulsars.

The audio on the disc includes greetings in 55 languages and 35 sounds from life on Earth, such as whale songs. It also holds 90 minutes of music and 115 images. The record includes instructions on how to play it, similar to a vinyl record player.