Voyager 1’s tryst with Jupiter and Saturn

On November 6, 1980, Voyager 1 snapped a picture of Saturn while still 8 million km away from it. Scientists discovered a 15th moon orbiting Saturn from the photo the following day. In a year in which it has completed 45 years of operation, A.S.Ganesh takes a look at some of the many learnings from Voyager 1’s visits to Jupiter and Saturn…

You must be aware that the twin Voyager probes are now travelling in interstellar space, 45 years since their launch. Before they got there, however, they visited the gas giants in our solar system, gleaning a wealth of information from the flybys. While Voyager 2 flew by all four gas giants – Jupiter, Saturn, Uranus, and Neptune, – Voyager 1 focussed on Jupiter and Saturn.

Even though Voyager 1 is the first spacecraft to travel beyond the solar system and reach interstellar space, it wasn’t the first of the probes to be launched. Launched on September 5, 1977 – two weeks after Voyager 2 – Voyager 1, however, was the first to race to Jupiter and Saturn.

The Voyager missions were planned in such a way that they could maximise a special alignment of the outer planets that happens only once in 176 years. This alignment aided the spacecraft to efficiently use their limited fuel as they moved like a slingshot from one planet to another using gravitational assist.

All the successes that Voyager 1 has achieved might have come to nothing right on the day of the launch. Its rocket came within 3.5 seconds of running out of fuel, meaning Voyager 1 wouldn’t have even got off the ground.

Once it did, however, it raced past its twin, going beyond the asteroid belt before Voyager 2 did. And in April 1978, Voyager 1 beamed back the first pictures of Jupiter back to Earth. By March 1979, it had spotted a thin ring around the giant planet. Apart from sending back detailed photographs of Jupiter’s Galilean moons (Io, Europa, Ganymede, and Castillo), Voyager 1 also found two new moons – Thebe and Metis.

Voyager 1 collected plenty of data and also made some interesting discoveries about Jupiter’s satellites. Following its closest approach to Jupiter on March 5, 1979, when it came within 2,80,000 km, it headed over to Saturn, a journey that took it just a little over a year.

Just like how its visit to Jupiter had a lot of findings, so it was with Saturn as the ringed planet revealed many of its secrets. As it flew ever closer to Saturn in October-November 1980, Voyager 1 spotted a number of moons, observed its rings and already known moons, and collected data that had scientists digging for decades.