Representative image of Voyager
When NASA launched Voyager 1 in September 1977, it was expected to explore exoplanets before continuing its journey into deep space. Nearly 49 years later, the spacecraft is still sending information to Earth from a distance of about 25 billion kilometers, making it the farthest human-made object ever.It’s hard to imagine the distance. Voyager 1 is now more than 170 times farther from the Sun than Earth. Even light, which travels at about 300,000 kilometers per second, takes more than 22 hours to travel that distance.This also means that talking to Voyager 1 is not fast at all. It takes a transmitter from Earth more than 22 hours to reach the spacecraft. Once Voyager 1 responds, it takes another 22 hours or more for the response to come back.
This means that each exchange with the spacecraft takes approximately two days.Because of the delay, NASA engineers cannot control the spacecraft in real time. They send out orders, wait patiently, and don’t know until about two days later whether everything is working as planned.
Where no spacecraft has arrived before
In 2012, Voyager 1 made history by crossing the edge of the heliosphere, the point where the Sun’s influence ends and interstellar space begins, and became the first spacecraft to enter interstellar space.
Although it is far beyond the outer limits of our solar system, Voyager 1 has not stopped working. Two of its science instruments are still collecting information about the spacecraft’s environment. This data travels billions of kilometers before it reaches giant antennas on Earth, where scientists receive and study it.The signal is incredibly weak when it arrives. However, NASA was still able to detect it after its journey through space.
Image of Earth taken by Voyager 1
What keeps Voyager going?
One of the reasons Voyager 1 survived for so long is that it doesn’t rely on sunlight for energy. At such a great distance from the sun, solar panels would no longer be useful. Therefore, the spacecraft carries plutonium-powered generators. The heat it produces is converted into electricity, which Voyager 1 uses to continue operating even in the darkness of deep space.When Voyager 1 was launched, its power system produced about 470 watts of electricity.
Today that’s down to about 230 watts. The amount of energy available decreases slightly each year as plutonium slowly decays.That may not seem like a lot of electricity, but it was enough to keep the spacecraft alive and send messages across 25 billion kilometers.
NASA counts every watt
The biggest challenge facing Voyager 1 today is not its distance from Earth, but rather the shrinking energy supply. To make electricity last as long as possible, NASA gradually turns off systems that are no longer needed.
Over the years, scientists have turned off heaters and some science instruments so the spacecraft can continue transmitting data.In 2026, another detector was turned off to save energy. NASA believes that Voyager 1 may continue to transmit essential engineering data at least into the 2030s if remaining energy is carefully managed. However, as the years go by, more gadgets will have to be shut down one by one.Voyager 1 is expected to reach another historic milestone around November 2026. By then, it will be approximately one light-day away from Earth. This means that even a signal traveling at the speed of light would take a full 24 hours to reach the spacecraft.