Voyager Program
What exists outside of our solar system? It's a question scientists are working to answer using theoretical astronomy, powerful telescopes, and satellites. Voyager 1 and Voyager 2 were launched during the 1970s on a fly-by mission of Jupiter, Saturn, Uranus, and Neptune, but they have long outlived their original mission. You can see where in our galaxy the Voyager satellites are by visiting this NASA website. Today, both Voyager satellites are exploring interstellar space. Before that however, the satellites took images of planets a little closer to home.
Voyager Model
Source: NASM
Voyager Satellite Instruments
Source: NASA/JPL
A 3D model of NASA's Voyager spacecraft.
Source: NASA Visualization Technology Applications and Development (VTAD)
Published: April 22, 2019
When were the Voyager Satellites launched?
Voyager 2 was actually launched first, in August 1977. Voyager 1 was launched in September 1977, but was set on a faster trajectory and reached Jupiter first, so it got the "1" designation. Voyager 1 reached interstellar space in 2012, and Voyager 2 reached interstellar space in 2018. Both satellites are now exploring Space outside of our solar system, and will continue to do so until their instruments stop working.
What was the goal of the Voyager program?
The Voyager satellites were launched with the original mission of conducting close up studies of Jupiter and Saturn, with the hope of also conducting surveys of Uranus and Neptune. NASA scientists hoped to use a rare planetary alignment (that only happens every 175 years!) to swing the satellites from planet to planet using gravitational force instead of the satellites' onboard propulsion system! It worked, and the satellites took images of the four planets and 48 of their moons - discovering some of them for the first time! After the successful completion of this first mission, the Voyager satellites embarked on a second stage: leaving the solar system and exploring interstellar space.
What are some of the things we've learned from the Voyager satellites?
No spacecraft has gone further inter interstellar space than Voyager 1. The satellite was the first spacecraft to cross the heliosphere, which is the boundary where the Sun's gravitational influence is weaker than influences from outside of our solar system. Voyager 1 discovered:
two new moons orbiting Jupiter and a thin ring around the planet
five new moons and a new ring around Saturn
Voyager 2 is the only spacecraft to study Saturn, Jupiter, Uranus, and Neptune at a close range, and was the first artificial satellite to fly past both Uranus and Neptune. Voyager 2 discovered:
a 14th moon orbiting Jupiter
10 new moons and 2 new rings around Uranus
5 moons, four rings, and a "Great Dark Spot" at Neptune
Triton
Triton is one of Neptune's moons. Like our Moon, Triton orbits Neptune as one of its natural satellites. Voyager 2 captured photos of Triton in August 1989 as the satellite flew by the moon. Voyager 2 took detailed pictures of two thirds of Triton's surface.
In this section of Triton's northern hemisphere, most of the land is covered by circular depressions and rugged ridges. Scientists don't know how they formed, but some suggest that they were created by the melting and collapse of the planet's icy surface. How does this terrain formation differ from the way the surface changes on Earth?
Image Credit: NASA/JPL
This image from Voyager 2 captured an area of cliffs on Triton's surface. The cliffs may have been caused by the melting of surface materials or by the flowing of some sort of unknown fluid in Triton's past. How does this compare to the way cliffs are formed on Earth?
Image Credit: NASA/JPL
This picture capture's Triton's "cantaloupe" terrain, characterized by irregular mounds of ice. These "blobs" are several hundred feet high and miles across, and were formed with the top crust of the planet shifted and buckled. How can analyzing Triton's surface help us understand its history?
Image Credit: NASA/JPL
How do these images help us learn about Triton?
Triton is one of the coldest objects in our solar system, and these images reinforce that knowledge; the surface of the planet is largely covered by frozen nitrogen. We can see this icy crust in the images Voyager 2 took. These images also show that Triton does not have a large number of impact craters, indicating that it is fairly young by astronomical standards.
What do these images tell us about the terrain on Triton?
These images show us how different Triton's terrain is from our own - from a frozen nitrogen surface to a "cantaloupe" like terrain, Triton is shaped by a very different series of forces than those on Earth. These images provide us some answers, such as what does a planet with a temperature of -391 degrees Fahrenheit look and act like, but it also leaves us with more. For example, what fluid shaped the planet's surface in the past?