- Almost 45 years after their launch, Voyager 1 and 2 are still going.
- But with power dwindling, the probes may soon reach the end of their scientific mission.
- Here are 18 pictures taken by the probes on their amazing journey.
- For more stories go to www.BusinessInsider.co.za.
The Voyager probes are pioneers of science, making it further into space than any other object made by humans.
Originally sent on a four-year mission to Jupiter and Saturn in 1977, the twin probes exceeded all expectations, and are still going 45 years later.
Among their achievements are the amazing photos of the solar system they beamed back before the cameras were shut down.
But now, they face a terminal problem: their power is running out, and NASA scientists are starting to shut down even more instruments on board to conserve energy.
As they near the end of their mission, here are 18 images from Voyager that changed science:
The Voyager probes were designed to visit Jupiter and Saturn.
The Voyager mission was made up of two probes, Voyager 1 and 2, which were launched in 1977 within a few months of each other.
The launches capitalised on a rare alignment of planets that allowed them to turbocharge their journeys into space.
This is what Voyager saw on its approach to Jupiter.
Voyager 1 and 2 reached Jupiter in 1979. They took about 50,000 pictures of the planet altogether, which greatly exceeded the quality of the pictures taken from Earth, according to NASA.
The pictures taught scientists important facts about the planet's atmosphere, magnetic forces, and geology that would have been difficult to decipher otherwise.
The probes discovered two new moons orbiting Jupiter: Thebe and Metis.
As well as a thin ring around Jupiter
The probe captured this picture as it was looking back at the planet backlit by the Sun.
Voyager 1's biggest discovery was volcanic activity at the surface of Io, Jupiter's moon.
Next stop: Saturn
In 1980 and 1981, the probes reached Saturn. The flyby gave unprecedented insight into the planet's ring structure, atmosphere, and moons.
Voyager taught scientists about the detail of Saturn's rings, here captured in false colour.
Enceladus, Saturn's moon, was seen in unprecedented detail by Voyager.
This picture, taken as the probe flew away, provided a unique view of the planet, letting us see the part in shadow.
By '86, Voyager 2 had made it to Uranus
Voyager 1 continued straight on and would not come across another planet on its journey out of the solar system.
But Voyager 2 kept on its exploration of our nearest planets, passing within 50,600 miles of Uranus in January 1986.
It discovered an extra two rings around Uranus, revealing the planet had at least 11, not 9.
Its pictures of Uranus' largest moons revealed their complicated geological past. It also uncovered 11 previously unseen moons.
Here is a picture of Miranda, Uranus's sixth-biggest moon.
Voyager 2 was the first spacecraft to observe Neptune close up.
In 1989, 12 years after its launch, Voyager 2 passed within 3,000 miles of Neptune.
A picture shows the blue Neptune in full.
A picture shows Triton's rough surface.
It captured Triton, Neptune's moon in unprecedented detail.
Another shows Triton's southern hemisphere.
It captured Neptune's rings.
Here, the crescent shape of Neptune's south pole was seen by Voyager as it departed.
Voyager 2 would never take pictures again. Since it wouldn't come across another planet on its ongoing journey, NASA switched off its cameras after its flyby of Neptune to conserve energy for other instruments.
Voyager took 60 images of the solar system from about 4 billion miles away.
As its last photographic hurrah, Voyager 1 took 60 images of the solar system from 4 billion miles away in 1990.
It gave us the Earth's most distant self-portrait, dubbed the "pale blue dot"
This is likely to remain the longest-ranging selfie in the history of humankind for some time, a portrait of the Earth from 4 billion miles away.
After this picture, Voyager 1's cameras were also switched off to save energy. It is possible for the probes' cameras to be switched back on, but it is not a priority for the mission.
Beyond the solar system
Though the probes are no longer sending pictures, they haven't stopped sending crucial information about space.
In 2012, Voyager 1 became the first human-made instrument to cross into interstellar space by passing the heliopause, the boundary between our solar system and the rest of the universe.
The probes keep sending back measurements from interstellar space, like weird hums likely coming from vibrations made by neighbouring stars.
Even after their instruments are switched off, the probes' mission continues
Now NASA is starting to switch off the probes' last instruments with the hope of extending their life to the 2030s.
But even after all instruments become quiet, the probes will still drift off carrying the golden record, which could provide crucial information about humanity should intelligent extraterrestrial life exist and should it come across the probes.