Emily Lakdawalla • August 17, 2017

Celebrating the 40th anniversaries of the Voyager launches

Sunday, August 20 marks the 40th anniversary of the launch of Voyager 2. Tuesday, September 5, will be the 40th anniversary for Voyager 1. Round anniversaries like these have no special significance for spacecraft that have departed Earth's orbit; the significance is for those of us that the spaceships left behind on a planet that still revolves around the Sun once a year. Anniversaries are a good time to look back and consider our past. Throughout the next three weeks, we'll be posting new and classic material in honor of the Voyagers. Here's a preview of that material; I'll update this post with links as it's published.

NASA / JPL

Mariner-Jupiter-Saturn 1977 Spacecraft Artwork, 1975

NASA and JPL initially referred to what became the Voyagers as the Mariner-Jupiter-Saturn 1977 Project. The two Voyagers were advanced versions of the Mariner-class spacecraft that JPL had flown successfully to Venus, Mars, and Mercury. Shown here is a 1975 JPL artist's rendering of Voyager after encountering Jupiter and, after a gravity assist, approaching Saturn.

It begins with yesterday's Planetary Radio show, in which Mat Kaplan interviews Ed Stone -- Voyager's one and only mission project scientist since launch -- on what Voyager has done, and what the mission is still doing.

The Planetary Society was forming at the time of the Voyager launches, and marks its first year, 1980, as the one in between the Voyager encounters of Jupiter and Saturn. Next week, look forward to a walk through The Planetary Society's first ten years, intertwined with the Voyager planetary encounters, as seen through the lens of our member magazine, The Planetary Report. In the era before widespread use of the Internet, receiving our magazine was the first moment that many space fans saw some of the awesome images from the encounters. We'll post six full issues of The Planetary Report, containing scientists' first impressions of the data returned from the four giant planets.

The images, of course, are what excited the public most about these missions. I've requested three posts from image processing enthusiasts, containing some of the best photos and movies from the Voyagers, both old and new material. Ted Stryk will share some of his work on outer planet moons; Ian Regan has some exciting new videos from Jupiter; and Bjorn Jonsson has produced some new images and movies of all the planets.

NASA / JPL / Ted Stryk

Voyager 2's Oberon imaging sequence

These represent the sharpest views that can be pulled out of the data captured by Voyager 2 during its Uranus flyby.

Finally, we'll hear from some of the scientists who were involved with the missions during the planetary encounters, including late Planetary Society founder Carl Sagan. And on the day of the Voyager 1 launch anniversary, September 5, you can tune in to Facebook Live for a conversation between me and Planetary Society founder Lou Friedman about the Voyager missions and the Planetary Society. Stay tuned for further details about that.

Incredibly, it's possible that these spacecraft may last to the next big decadal anniversary, the 50th, in 2027. As Ed Stone explains in yesterday's Planetary Radio, the power sources decline in output by 4 watts per year. They are conserving power by shutting off instruments and components as needed to keep the spacecraft's main computer and transmitter operating, and Stone estimated that by doing so they could keep the spacecraft alive until 2030.

NASA / GSFC Conceptual Image Lab

Voyager 2 in the solar wind

This artist's concept shows the venerable Voyager 2 spacecraft journeying out of the solar system at 15 kilometers per second (34,000 miles per hour) with the solar wind streaming past it four times faster.

Because The Planetary Society has been covering Voyager for so long, there's a lot of background material on our website already on the accomplishments and status of the Voyager missions.

Finally, here are some interesting items from NASA's technical archives: