NASA’s Search for Aliens: The Voyager Missions
Hello, friends! Are we alone in the universe, or is there other intelligent life out there? If aliens exist, they might be wondering the same thing: are they alone, and can they connect with other beings like us? NASA has been working on ways to send messages into space in hopes that if there are aliens, they might hear us.
In 1977, NASA launched Voyager 1 with the mission to explore our solar system’s outer planets and beyond—into interstellar space. The area between solar systems is called interstellar space, and there are millions of such systems in our galaxy. So far, NASA has only launched five spacecraft to explore this distant region. These include Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, and New Horizons. Of these, only Voyager 1 and Voyager 2 have reached interstellar space.
These two spacecraft gave us stunning photos of planets like Jupiter, Saturn, Uranus, and Neptune. Voyager 2 is still the only one that has gone close to Uranus and Neptune. Voyager 1, on the other hand, has traveled farther from Earth than any other human-made object and is now more than 24.7 billion kilometers away.
The most amazing thing about the Voyagers is that they carry messages for potential alien life. These messages were sent with the hope that if aliens find the Voyagers, they’ll learn something about us.
The idea for the Voyager missions started in 1965. A NASA engineer noticed that in the late 1970s, the planets Jupiter, Saturn, Uranus, and Neptune would align in a rare way that happens only once every 175 years. This alignment would allow a spacecraft to use the planets’ gravity to “slingshot” past them with very little fuel. This technique, called Gravity Assist, uses a planet’s gravity to speed up and redirect a spacecraft.
Based on this idea, NASA planned the Voyager 1 and Voyager 2 missions. They launched Voyager 2 on August 20, 1977, and Voyager 1 sixteen days later. Voyager 1 took a faster route and reached Jupiter first. It sent back amazing photos, including a time-lapse of Jupiter that helped us see the planet and its moons more clearly than ever. This was also when we discovered that Jupiter has faint rings, like Saturn, though they are harder to see.
Voyager 1 also discovered active volcanoes on Jupiter’s moon Io—the first time we had seen volcanic activity on another world. Thanks to the Voyagers, we learned that Jupiter has many moons. By today, we know it has at least 95.
In November 1980, Voyager 1 reached Saturn and discovered new moons there too. One of the most fascinating moons it studied was Titan, which has rivers and lakes of liquid, making it the only other object in our solar system with liquid on its surface.
After Saturn, Voyager 1 and Voyager 2 took different paths. Voyager 2 went on to visit Uranus in 1986 and Neptune in 1989, becoming the only spacecraft to visit these distant planets. Meanwhile, Voyager 1 continued straight out of the solar system.
In 1990, Voyager 1’s mission officially changed to exploring interstellar space. It took a famous photo of Earth from about 6 billion kilometers away, called the “Pale Blue Dot,” showing Earth as a tiny blue speck in the vastness of space.
As Voyager 1 continued, it passed a region called the termination shock, where the solar wind slows down. The solar wind is a stream of charged particles coming from the Sun that forms a bubble around our solar system, known as the heliosphere. This bubble protects us from harmful interstellar radiation.
After passing through this region, Voyager 1 finally entered interstellar space on August 25, 2012. NASA confirmed this with data from Voyager 1’s plasma wave instruments, which showed changes in electron density as the probe moved beyond the Sun’s influence. Voyager 2 entered interstellar space about six years later, in 2018.
Both Voyagers carry messages for any alien life they might encounter. These messages are on golden records, which include sounds and images from Earth, showing what life is like on our planet. This was NASA’s way of introducing humans to any intelligent life that may one day find these spacecraft.
NASA had tried sending messages into space even before the Voyagers. In the 1970s, Pioneer 10 and 11 carried small metal plates with symbols showing Earth’s location and images of humans. But the Voyagers’ records contain much more detail, using technology that allowed them to include more information.
These records are 12-inch, gold-plated discs, similar to old phonograph records, that play sounds. They store the sound waves in grooves, which a needle can play back to create sound. If aliens ever find the Voyagers, they might learn a bit about us by listening to these messages and seeing the pictures.
