It is almost half a century since Voyager 1 was launched from Cape Canaveral in Florida on a mission to study Jupiter, Saturn, and the atmosphere of Titan. It continues to send data back to Earth.
Although engineers reckon that the aging spacecraft might survive well into the 2030s before eventually passing out of range of the Deep Space Network, the spacecraft’s cosmic ray subsystem was switched off in 2025. More of the probe’s instruments are earmarked for termination as engineers eke out Voyager’s power supply for a few more years.
On September 5, 1977, the power situation was a good deal healthier when the mission got underway. Launched just over two weeks after Voyager 2, Voyager 1 was scheduled to make flybys of Jupiter and Saturn. It skipped a visit to Pluto in favor of a closer look at the Saturnian moon Titan, which had an intriguing atmosphere.
The launch was the final one for the Titan IIIE rocket and was marred slightly by an earlier-than-expected second stage engine cutoff. NASA averted disaster by using a longer burn of the Centaur stage to compensate, and Voyager 1’s mission to Jupiter, Saturn, and beyond began.
Voyager 1’s journey to the launchpad began with the “Grand Tour” concept of the 1960s, in which Gary Flandro of the Jet Propulsion Laboratory (JPL) noted an alignment of Jupiter, Saturn, Uranus, and Neptune would occur in the 1970s, allowing a probe to swing by all the planets by using gravity assists.
Two missions were planned – one to be launched in 1977 to Jupiter, Saturn, and Pluto, and another in 1979 to visit Jupiter, Uranus, and Neptune. The concept gained support, but with costs spiraling and NASA also trying to develop the Space Shuttle, it was scaled back to visit two planets with two probes, derived from the Mariner program.
Indeed, the mission was known as the Mariner Jupiter-Saturn project until shortly before the 1977 launch, when the name “Voyager” was selected.
One of the Voyager scientists, Dr Garry Hunt, told The Register that the idea of doing a Jupiter-Saturn-Uranus-Neptune mission had never really gone away, and engineers fueled the spacecraft fully expecting to be granted an extension.
“We knew that if you filled up to brimming point the spacecraft with all the fuel it ever needed, it’d be OK,” recalled Hunt. “We did. But we never told anybody.”
Voyager 1 could have performed the same Grand Tour as Voyager 2, and would have if disaster had befallen the latter at or soon after launch. However, it was Voyager 2 that swung past Uranus and Neptune, while Voyager 1 took a trip past Titan before finally heading away from the planets. It used its cameras to take one last set of images – the famous “Solar System Family Portrait,” comprising six of the solar system’s eight planets and, of course, the “Pale Blue Dot” image.
Voyager took the images on February 14, 1990. “That was always our farewell thing,” said Hunt. “That was our Valentine’s present for 1990.”
Farewell? Not quite. Voyager 1 continues to send data back to Earth, 48 years after its launch. Yes, there have been issues – a recent computer problem onboard the probe required some impressive engineering on the ground to work around a failed component – but the mission continues, with every passing year a bonus. ®