NASA is slowly powering down the Voyager probes. Here are 18 groundbreaking photos from their 45-year mission.

The Voyager mission included two probes — Voyager 1 and Voyager 2 — which NASA launched in 1977 within a few months of each other.

The launches capitalized on a rare alignment of planets that allowed them to turbocharge their journeys into space.

NASA originally built the probes to last five years, but have exceeded that lifespan many times.

Voyager 1 and Voyager 2 reached Jupiter in 1979. They took about 50,000 pictures of the planet in total, which greatly exceeded the quality of the pictures scientists took 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 probe captured this picture as it was looking back at the planet backlit by the Sun.

In 1980 and 1981, the probes reached Saturn. The flyby gave scientists unprecedented insight into the planet's ring structure, atmosphere, and moons.

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.

Here is a picture of a Miranda, Uranus's sixth-biggest moon.

In 1989, 12 years after its launch, Voyager 2 passed within 3,000 miles of Neptune.

It captured Triton, Neptune's moon in unprecedented detail.

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.

As its last photographic hurrah, Voyager 1 took 60 images of the solar system from 4 billion miles away in 1990.

This is likely to remain the longest-range selfie in the history of humankind for some time: a portrait of the Earth from 4 billion miles away.

After this picture, NASA switched off Voyager 1's cameras to save energy. NASA could switch the probes' cameras back on, but it is not a priority for the mission.

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.

Voyager 2 was the second, crossing the boundary in 2018. It then revealed there was an extra boundary surrounding our solar bubble.

The probes keep sending back measurements from interstellar space, like weird hums likely coming from vibrations made by neighboring stars.

Now NASA is planning to switch more off the probes' 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.