“Voyager” space probes 45 years down the road: beyond the sun’s heliosphere, energy wanes

Already 45 years in space
The “Voyager” probes have exceeded all limits

The “Voyager” space probes have now been in motion for about 45 years. Today they are the most distant man-made objects from Earth and have long penetrated previously unexplored areas. But now they are starting to weaken.

Far, Farther, ‘Voyager’: Man-made objects have never been as far from Earth as these twin probes from the US space agency NASA. “Voyager 1” and “Voyager 2” have been on the road for about 45 years. Both have since left the Sun’s heliosphere and entered regions never before explored by spacecraft.

But the longest journey in space history appears to be coming to an end: Although both unmanned probes are still flying and continuing to send back data, NASA scientists have already turned off many of the instruments on board over the past three years for to extend the remaining energy. The power of detectors is decreasing year by year – and engineers have to adapt to it. To do this, they often have to read documents that are decades old or contact long-retired NASA engineers.

With “Voyager 1” scientists are also currently struggling with a data problem. Although the sensor appears to be working normally, the control system shows completely different data. “Such a mystery is not surprising at this point in the mission,” said lead scientist Suzanne Dodd. “The probes are both nearly 45 years old, much older than the mission planners ever expected. And we’re beyond the Sun’s heliosphere — a high-radiation environment that no spacecraft has ever flown by. So for engineers, there are big challenges.”

Originally, the Voyager mission of the two “cosmic high-flyers,” considered one of the most successful ventures in NASA history, was planned for four years. “Voyager 2” was launched on August 20, 1977, and its twin sister “Voyager 1” shortly after on September 5, 1977.

Beyond every border

Both probes, each weighing about a ton, had a rendezvous with Jupiter and Saturn, Voyager 2 visited Uranus and Neptune. The probes also studied nearly 50 moons. The pair sent back stunning photos of Jupiter’s atmosphere, active volcanoes on Jupiter’s moon Io, and Saturn’s rings.

As a precaution, the probes were originally equipped with backup systems. The “Voyager” twin operates on long-life plutonium generators.

Voyager 1 is now more than 23 billion kilometers from Earth, further than any other spacecraft, while Voyager 2 is about 20 billion kilometers. In 2012, Voyager 1 became the first spacecraft in human history to leave the solar system. Thanks to its previous launch, Voyager 2 is the longest continuously operating spacecraft. In 2018, Voyager 2 also left the sun’s heliosphere.

However, there are various definitions of the boundaries of the solar system. It is often identified with the edge of the heliosphere, a kind of bubble in interstellar space formed largely by the solar wind. According to other experts, the limit is further away and lies behind the so-called Oort Cloud, a collection of small objects that, despite the enormous distance, are still under the influence of the Sun’s pull.

music in the bag

“Our energy budgets are getting tighter, but our team assumes we can do science for at least another five years,” the researchers said recently via the short messaging service Twitter. “Maybe we can celebrate our 50th anniversary or even operate into the 2030s.”

Even if they are silenced, the scouts will not stop flying. They are currently traveling through the Galaxy at about 61,000 kilometers per hour (“Voyager 1”) and about 55,000 kilometers per hour (“Voyager 2”). The “Voyager” twins carry with them on data carriers music from rock and roll legend Chuck Berry, as well as classical music by Bach, Mozart and Beethoven, as well as sounds from countries such as Australia, Bulgaria, Japan and Peru and 115 images and greetings to possible aliens in 55 different languages.

“It’s hard to see the end coming,” scientist Alan Cummings, who has been tracking the probes for decades, told Scientific American. “But we did great things.”

(This article was first published on Saturday, July 2, 2022.)

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