Space probes Voyager 1 and Voyager 2 were launched 45 years ago and now float billions of miles from Earth. The American space agency NASA maintains contact with the equipment to this day, despite the very weak signal.
By Rutger OttoIt’s almost unimaginable, but Voyager 1 and 2 are currently orbiting about 13.5 billion kilometers and 19 billion kilometers from Earth, respectively.
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There are no other man-made objects that are further away. And the probes float on through the dark universe; they never come closer.
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That NASA is still in regular contact with the probes is therefore quite special. The organization uses radio signals to maintain the exchange of data. A signal is sent from Earth, which takes more than 21.5 hours to reach Voyager 1. A signal reaches Voyager 2 after eighteen hours.
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Sensitive antenna registers the weakest signal
The Voyagers are equipped with sensitive antennas that can pick up signals. Once contact is established, the probes return data with a 20-watt signal. That signal gets weaker and weaker as it travels to Earth. Once here, the radio signal is barely perceptible.
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That is why there are gigantic receivers on Earth that are so sensitive that they can distinguish even the weakest signal from the noise around it. NASA uses its Deep Space Network to talk to the probes. There are centers in three places on the earth with very powerful radio transmitters and sensitive receivers that together form the network.
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The centers are located in Madrid (Spain), Goldstone (US) and Canberra (Australia). They are scattered across those locations because contact with the space probes is always possible, no matter how the Earth is rotated. The dishes are also located in remote areas, so that the reception signal is disturbed as little as possible by ambient noise.
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—In the coming years we will lose contact
Technically, it would be possible to track the Voyagers in this way for decades to come. Still, sometime in the next few years, we’ll lose contact with the probes.
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That’s because the probes are running out of energy. They are equipped with a nuclear battery that is not recharged. It made no sense to equip the Voyagers with solar panels, because the devices travel too far outside the radiation range of the sun to charge.
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In recent years, NASA has remotely disabled various instruments, such as cameras, in order to use the probes as economically as possible.
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But after 45 years, the Voyager missions, which in 1977 were thought to last five years, are finally in sight. After the last contact, the probes will float endlessly through the universe, but NASA will never hear from them again.
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