NASA's Voyager 1 and 2 missions are the longest-running missions in the history of the iconic space agency. They have logged 45 years in space, bringing us close-up images of Uranus and Neptune.

Voyager 1 was responsible for the 'pale blue dot' image taken at the suggestion of famous astrophysicist and science popularizer Carl Sagan. That image, and Sagan's words (in the video below), brilliantly encapsulate the legacy of the Voyager missions.

They altered our perspective on our place in the universe and paved the way for following missions, such as the Jupiter Cassini mission and even this year's James Webb telescope observations. Pretty impressive for two space probes that, as NASA puts it, have about 3 million times less memory than modern smartphones.

Voyager 2 was the first of NASA's two probes launched to investigate the outer planets of our Solar System. It launched on August 20, 1977, aboard a Titan IIIE-Centaur from Cape Canaveral Space Launch Complex 41. Voyager 1 was launched roughly two weeks later, on September 5.

The Voyager spacecraft launches were timed to take advantage of an alignment of the outer planets that only occurs once every 176 years. The alignment would allow the probes to hop from one planet to the next with the help of a gravity boost.

Voyager 1 was tasked with taking images of and analyzing Jupiter and Saturn. In 1990, after having flown beyond Jupiter and Saturn, the Voyager team prepared to shut down the spacecraft's imaging equipment. Just before they did, Carl Sagan suggested they train the equipment back on Earth. The results can be seen in the video above.

Voyager 2 also took images of Saturn and Jupiter, but it then moved on towards Uranus and Neptune. Voyager 2 is currently about 12 billion miles (19 billion kilometers) away from Earth. Voyager 1 crossed the boundary into interstellar space in 2012, while Voyager 2 crossed the outer edge of our solar system in 2018.

The Voyager team planned for the interstellar phase of the mission — using the probes' Plasma Science Subsystem instruments, they were able to measure the drop in solar wind when each of the spacecraft left the outer edges of the Solar System.

On its flyby of Jupiter, Voyager 2 captured images of the gas giant's Great Red Spot and also took detailed images of the planet's satellites. Voyager 1 and 2 both discovered moons orbiting Jupiter, including Thebe, Metis, and Adrastea. Adrastea is estimated to measure only about 19 miles (30.5 kilometers) in diameter.

After also capturing many images of Saturn and taking in new details of its icy moons and its rings, Voyager 2 used a gravity assist to travel on to Uranus. This is where its path altered from Voyager 1, which was to focus on Jupiter and Saturn before traveling, making its way to the boundary of our solar system.

Voyager 2 became the first spacecraft to visit the ice giant Uranus when it made a close approach on January 24, 1986. The spacecraft's readings showed that Uranus' atmosphere is roughly 85% hydrogen and 15% helium. It also discovered 10 moons orbiting Uranus as well as a magnetic field that was, strangely, 55 degrees off the planet's axis — scientists are still unsure today why Uranus' magnetic field is off kilter. Voyager 2 also captured impressive images of Uranus' moon Miranda, revealing its strikingly uneven surface.

After Uranus, Voyager 2 then went on to make its closest flyby of Neptune on August 25, 1989, flying roughly 3,000 miles above the planet's surface. The spacecraft discovered five new moons and four rings around what is now considered the most distant planet from the sun in our solar system — Pluto hadn't been disqualified at the time. Voyager 2 is the only human spacecraft to have flown past Neptune, making its data invaluable even today.

Remarkably, NASA states that Voyager 2 has enough fuel to keep running until about 2025, at which point the probe will be roughly 11.4 billion miles (18.4 billion kilometers) away from Earth. It will continue to travel out into the Milky Way even when it can no longer send signals back to Earth — according to NASA's estimations, for example, Voyager 2 will be within 1.7 light-years (9.7 trillion miles) of the star Ross 248 in about 40,000 years. A remnant of humankind floating through space for eons to come, marking the beginnings of its attempts to explore the universe.