45 years after launch, NASA's Voyager probes still blazing trails billions of miles away

Even after 45 years, Voyager 1 and Voyager 2 are still communicating with Earth as they explore interstellar space.

Voyager 2 lifts off at the Kennedy Space Center on Merritt Island, Fla., on August 20, 1977. The probe was launched a couple weeks before Voyager 1 and ultimately became the second-farthest man-made object from the Earth. Photo courtesy NASA
1 of 7 | Voyager 2 lifts off at the Kennedy Space Center on Merritt Island, Fla., on August 20, 1977. The probe was launched a couple weeks before Voyager 1 and ultimately became the second-farthest man-made object from the Earth. Photo courtesy NASA

Aug. 19 (UPI) -- Forty-five years ago, NASA launched the first part of its most ambitious deep space mission in its history -- a spacecraft called Voyager 2, which is still communicating with scientists on Earth at a distance of more than 12 billion miles away.

Voyager 1 and Voyager 2 are both in interstellar space. In fact, they are two of only five space probes from Earth that have left the solar system.


Because of planetary alignment and the trajectory needed for its mission, Voyager 2 actually launched first on Aug. 20, 1977. Voyager 1 followed on Sept. 5, and the two space probes began charting the far reaches of our solar system.

The two probes are still operating as NASA's longest international mission, and are expected to keep operating for at least a few more years before they finally run out of power.


Saturday will mark 45 years since the start of the mission.

Even though NASA has achieved a number of major victories in space, such as the Apollo moon landings and dozens of space shuttle missions, the Voyager spacecrafts are still fondly revered by scientists and the space-loving public.

Voyager 1 and Voyager 2, both launched in 1977, are graphically represented in their positions several years ago at the edge of the heliosphere, the barrier the sun creates around the planets in the solar system. Image courtesy NASA

The resilient machines have even become part of popular culture, fictionally appearing in a number of television programs and films. A fictional Voyager probe was a major plot point in the first Star Trek film in 1979 and one was responsible for bringing a benign alien life form to Earth in the 1984 film Starman.

"The Voyagers have continued to make amazing discoveries, inspiring a new generation of scientists and engineers," Suzanne Dodd, Voyager project manager at NASA's Jet Propulsion Laboratory in California, said in a statement Wednesday.

"We don't know how long the mission will continue, but we can be sure that the spacecraft will provide even more scientific surprises as they travel farther away from Earth."


Following their launches, both probes became part of a "grand tour" to explore the outer planets in great detail for the first time, including Jupiter and Saturn, and to beam back data about the solar system's largest plants and their moons. Voyager 1, which was moving faster, ultimately overtook Voyager 2 and reached the outer planets first.

Later in the mission, Voyager 2 became the first -- and to date still the only -- spacecraft to fly exceptionally close to the two outermost planets, Uranus in 1986 and Neptune in 1989.

On its way out of the solar system in 1990, Voyager 1 turned its onboard camera around to take a snapshot of all the planets except Mercury, which was out of view. The image is now known as the "family portrait." At the time, the craft was almost 4 billion miles from Earth.

"Today, as both Voyagers explore interstellar space, they are providing humanity with observations of uncharted territory," Linda Spilker, Voyager's deputy project scientist at JPL, said in a statement.

"This is the first time we've been able to directly study how a star, our sun, interacts with the particles and magnetic fields outside our heliosphere ... and providing key information for future missions."


As Voyager 2 conducted its flybys, Voyager 1 was first to reach the boundary of the heliosphere, the protective bubble created by the sun's magnetic field and the outward flow of solar wind.

Both of the space probes captured stunning images of all the planets beyond the Earth, including many of their moons, and gathered surprising data about a lot of the celestial bodies.

For example, the Voyagers discovered that Enceladus, one of Saturn's moons, has a vast salt-water ocean beneath its surface and likely hydrothermal vents -- conditions that are exceptional for creating life. Large geysers emerging from the moon´s surface clued scientists to this fact.

Decades later in 2012, Voyager 1 reached the boundary of the heliosphere and exited the solar system and Voyager 2 followed in 2018.

Upon its exit, Voyager 1 discovered that the bubble-like heliosphere blocks about 70% of cosmic rays or energetic particles created by exploding stars.

Both Voyager probes are powered by radioisotope thermoelectric generators that contain plutonium, which gives off heat that is then converted into electricity to power the equipment. In a sign of the times, they also each carry an eight-track tape player to record and transmit data -- about 38,000 times slower than modern 5G Internet speeds.


But perhaps most famously, the Voyager probes also contain a message in a bottle of sorts -- a golden record that contains data about life on Earth, in case either of them encounter intelligent life out there someday, even after they lose power.

The golden record contains audio messages in many languages and images that describe the human form and elements of the Earth, including a crude map that indicates where we are in the solar system.

A simulated view approximates Voyager 1's perspective when it took its final series of images, known as the "Family Portrait," in February 1990. Image courtesy NASA

As wildly successful as both probes have been, however, they have not been without their share of problems.

Earlier this year, Voyager 1 encountered an issue in which data readouts from its attitude articulation and control system, or AACS, wasn´t reflecting the craft´s true orientation. Scientists found that the problem was with the production of status data and not the system itself, meaning it wasn't a critical mission problem.

After its flyby of Saturn in 1980, the camera on Voyager 2 locked up and wasn't functioning properly. It was a brief issue, however, and it returned to service.


As of Friday, Voyager 1 was more than 14.5 billion miles away from the Earth -- more than twice the distance between Pluto and the sun. Voyager 2 is more than 12.1 billion miles away. NASA says next year, Voyager 2 will become the second-farthest artificial object from the Earth, surpassing the Pioneer 10 probe launched in 1972. You can still keep tabs on both probes on NASA's Voyager website.

NASA expects Voyager 1 and Voyager 2 to run out of power -- officially ending their decades-long missions -- sometime in the mid-2020s.

Once the probes lose the ability to communicate with scientists on Earth, NASA says they will begin their final mission -- serving as "ambassadors" of our planet should they ever be found by intelligent life somewhere.

"The gold-coated records serve as a cosmic 'message in a bottle' for anyone who might encounter the space probes," NASA said. "At the rate gold decays in space and is eroded by cosmic radiation, the records will last more than a billion years."

Three other probes have also left the solar system -- Pioneer 10, Pioneer 11, launched in 1978, and the New Horizons probe that launched in 2006. Pioneer 10 lost contact with Earth in 2003 and Pioneer 11 in 1995.


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