24 January 2011
1986: Voyager at Uranus
Much of what we know about our solar system's seventh planet comes from Voyager 2's historic flyby 25 years ago today. The spacecraft returned a wealth of information about the ice giant. Voyager 2 is the only spacecraft that has visited Uranus and Neptune.
At closest approach, the spacecraft came within 81,500 km (50,600 miles) of Uranus's cloudtops on 24 January 1986. The thousands of images and reams of scientific data Voyager 2 sent back revealed a complex system of rings, moons and an unusual magnetosphere. Ten of the moons had never been seen before. The mission team also discovered two rings. It was an exciting time for planetary scientists.
In celebration of the encounter's silver anniversary, we asked past and present Voyager team members to share their favorite images and stories from the flyby. (5 images total):
"A view of the planet that is impossible to see from the Earth, no matter how terrific your telescope is, and it was a chance to really reflect on all the great results we had achieved."
- Candice Hansen
"Just in time for Uranus, I got my subscription to "Sky & Telescope." The first issue came a few months after the encounter. I opened the wrapper and found the Uranus crescent picture filling the cover. It is, in my view, the most aesthetical image of that encounter. This left a deep impression on me as it is comparable in beauty with the "final look back" image of Saturn, of which I had the poster of on the wall in my room. Perhaps I had a weak spot for special perspectives that the planets offered and which up to then were captured only by artists' imaginations.
At the time of the Voyager 2 Uranus encounter in January 1986, I was the equivalent of a high school senior back in Germany. Voyager 1 and 2 with their spectacular Jupiter and Saturn encounters years earlier inspired me at a critical preteen age to go into science in general and space science in particular. It was their fault! The images I saw on German TV news, newspapers and science programs influenced me. I remember watching JPL scientists celebrating their launches, planetary encounters and landings and these actually gave me goose bumps. In 1981 I got my first telescope. I learned to navigate the night skies at the expense of my parents' sleep, started organizing eclipse and comet (Halley) watches at my school and wrote articles about some of the latest news in astronomy and astrophysics for our high school student newspaper.
The Uranus encounter is special for me in the sense that no other spacecraft had been there before. Jupiter and Saturn, on the other hand, had been visited before by the Pioneers. True, the image quality improved significantly. But the quantum leap was achieved at Uranus. Ground based telescopes up to 1986 showed no more than a fuzzy bluish ball with little white dots (moons) around it.
A year ago I happened to become Voyager Program Scientist, which allows me now to directly work with the Voyager science team on behalf of NASA. This closes an incredibly unlikely circle from being inspired by the project to actually working for the project. The next encounter of both Voyagers is what I am looking forward to nowadays: the Heliopause. This is where the extended solar atmosphere ends. It will catapult humanity into a new era of exploration, from that of the sun and the solar system to that of interstellar space. For the first time, we will sample truly interstellar plasma. From where the Voyagers are now, it will likely take a few years. And that is the big difference between previous Voyager encounters and this one: we don't exactly know when we will reach interstellar space. So my calendar does not have a specific date penciled in. The Voyagers will tell us."
"(This image) meant a lot to me because, along with my team of trajectory and maneuver engineers (Steve Matousek, Chris Potts and Karl Francis), we did extensive analysis to create and execute the targeting strategy that made it possible. We had to account not only for accurate delivery of the spacecraft to the Miranda relative aim point, but also accurate camera pointing and image motion compensation. Truly an event to remember!"
- Arik Posner
- Robert Cesarone
"The job prospect for computer science graduates in1985 was pretty rosy and I always thought I would go work for IBM or HP or someplace like that. But a series of unexpected events put me on the VGR (Voyager) flight team getting ready for the Uranus encounter. It was like living in a different world. Never mind that I didn't know what everyone around me was doing; I didn't know what I was supposed to do either. However, it was amazing to watch what everyone was doing come together and turn into these incredible images we'd never seen before. It was such an infectious experience that I was seriously hooked. I like this image of Miranda that shows so much detail, the result of so much hard work of so many dedicated people. What a difference VGR had made! What a difference we had made!"
- Sun Matsumoto
"Without a doubt, my favorite image from the Voyager 2 Uranus flyby is this high resolution, high phase view of the rings. I vividly remember watching this image as it was displayed on the monitor for the first time and being completely amazed at what I saw! The nine narrow rings were now joined by a whole host of previously unknown belts of fine dust that were enhanced by the backlighting of the rings. Some of these wispy dust belts were even brighter than the major rings in this image. Later, I eagerly looked through the Voyager photopolarimeter (PPS) stellar occultation data of the Uranian rings for evidence of these newly discovered dust bands. What a spectacular flyby!"
- Linda Spilker
"The image of the Uranian ring system seen in forward scattered light. There were many images taken but most were underexposed. This is the only forward scattered light image to reveal structure (since it was the only 96-second exposure). When this image first came down, the science team was holding their daily science team meeting. The room exploded with excitement since the other forward scattered light images didn't reveal any structure. The funny part was that someone yelled out, 'This has to be a joke. Someone must've placed a Saturn image up on the monitors.' The room believed this statement and returned to their science discussions. Then someone else cried out, 'Look at the FDS count (the computer clock associated with formatting the data). It's a Uranus image!' The room exploded again with amazement."
- Randii Wessen
"When this image appeared on the screen, there was an audible gasp, followed by a comment that someone was trying to fool us by slipping in an image of the Saturn rings. Then as we looked closer and saw the short streaks indicative of stars and a long exposure image, we realized we were seeing for the first time a wide-angle image of the Uranus rings at very high phase angle, the only successful one of its kind during the Uranus encounter.
The image was obtained just a few days before the infamous Challenger explosion, which most of us viewed live in the same room in building 264, although the reaction was entirely different -- silent disbelief that what we were viewing had actually happened. I was serving as Voyager Assistant Project Scientist at the time, and although 25 years have elapsed since then, both events are still vivid in my recollection."
"My favorite image of the Uranus encounter is of the moon Miranda. To me it is one of the strangest objects in the solar system, ranking just behind Io in weirdness. It has all those striations. It looks like someone has been plowing the fields. And it has that weird chevron shaped region. Miranda is just plain weird."
- Ellis D. Miner
- Alan Cummings
"The Uranus encounter was my first exposure to the excitement of planetary missions. The "family portrait" was a composite of the best images that Voyager took of the moons of Uranus. They all looked somewhat different, even though they all orbit Uranus, just like siblings from the same parents look different and have different features. My second favorite is the Miranda image with the chevron feature shown prominently (see previous image). It's like God put his check mark of approval on the satellite."
- Suzy Dodd, Voyager Project Manager 2010