As Voyager 1 nears edge of solar system, CU scientists look back

In 1977, Jimmy Carter was sworn in as president, Elvis died, Virginia park ranger Roy Sullivan was hit by lightning a record seventh time and two NASA space probes destined to turn planetary science on its head launched from Florida.

The identical spacecraft, Voyager 1 and Voyager 2, were programmed to pass by Jupiter and Saturn on different paths, and Voyager 2 went on to visit Uranus and Neptune. University of Colorado Boulder scientists, who designed and built identical instruments for Voyager 1 and Voyager 2, were as stunned as anyone when the spacecraft began sending back data to Earth.

The discoveries started piling up: Twenty-three new planetary moons at Jupiter, Saturn, Uranus and Neptune; active volcanoes on Jupiter’s moon, Io; Jupiter’s ring system; organic smog shrouding Saturn’s moon, Titan; the braided, intertwined structure of Saturn’s rings; the solar system’s fastest winds (on Neptune, about 1,200 miles per hour); and nitrogen geysers spewing from Neptune’s moon, Triton.

Voyager 1, now about 11 billion miles from Earth and traveling 35,000 miles per hour, is expected to punch its way from the edge of the solar system into interstellar space in the coming months, with Voyager 2 is not far behind.

Charlie Hord, a former researcher at CU’s Laboratory for Atmospheric and Space Physics (LASP) and chief scientist on an instrument known as a photopolarimeter aboard Voyager, shakes his head as he recalls some of the discoveries. “All of the scientists were dazzled by the pictures of the moons of Jupiter and Saturn coming back. To finally look at them up close was the most remarkable thing I’ve ever seen in my life.” 

The LASP photopolarimeter, a small telescope that measured the intensity and polarization of light at different wavelengths, helped scientists determine the structure of Jupiter’s Great Red Spot, and to show that each dazzling ring of Saturn was made up of many smaller ringlets resembling phonograph record grooves.

On the off chance either spacecraft is encountered by aliens, each are carrying “Golden Records” -- gold-plated copper phonograph records with greetings in 54 languages, the sounds of surf, thunder, birds and whales and music snippets ranging from Bach and Beethoven to rock-and-roll legend Chuck Berry. 

Aided by the tireless work of many students, the CU photopolarimeter science team also included LASP Professor Larry Esposito, who said his biggest thrill of the mission was the Neptune fly-by in 1989 when the gas giant “went from being a small blurry dot to a planet with bright clouds and numerous moons and rings.”

The team also showed Saturn’s F ring was made up of three separate ringlets controlled by two small “shepherd satellites.”  In addition, density waves -- ripple-like features in the rings caused by the influence of Saturn’s moons -- allowed the team to estimate the weight and age of Saturn’s rings, Esposito said.

In 40,000 years, Voyager 1 will float within 9.3 trillion miles of the star AC+793888 in the constellation Camelopardalis. In 296,000 years, Voyager 2 will pass within 25 trillion miles of Sirius, the brightest star in the sky. Perhaps on the way, the spacecraft will encounter some musically inclined aliens up for a little Bach or Berry.