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Solar System Exploration at 50
Exploration Stories: Favorite Historical Moments

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Far-Reaching Missions
Far-Reaching Missions -- Voyager 2 and New Horizons
Mission Team, Jet Propulsion Laboratory
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Three members of the Voyager team (from left to right: David Grinspoon, Nick Schneider and John Spencer) point out Neptune on a mission board at NASA' Jet Propulsion Laboratory in 1989. Image Credit: NASA/JPL

Two missions -- 25 years between them -- one overarching goal:

Discovery.

August 25, 2014: Today, New Horizons will pass the orbit of our solar system's farthest most planet Neptune. It happens that this passing takes place on the very day that Voyager 2 encountered Neptune 25 years ago.

In the spirit of the Voyager 2 missions to Uranus and Neptune, New Horizons is going where no spacecraft has gone before.
"[New Horizons] will certainly provide us with new and exciting discoveries, just as Voyager did with its planetary flybys," remarked Suzy Dodd, Voyager Interstellar Mission project manager. (In 1989, Dodd was a Voyager 2 sequence integration engineer (SIE)).

Dr. Ralph McNutt stated concerning the upcoming milestone: "There have been only four space probes that have passed the orbit of Neptune: Pioneer 10 and 11, and Voyager 1 and 2. New Horizons will join that group on August 25, 2014. -- and they are all 'made in America.'" (Ralph McNutt, is a member of the New Horizons science team and was a plasma data team member on Voyager 2.

In celebration of the Voyager 2 Neptune encounter anniversary and in anticipation for what New Horizons will see, we asked team members to reflect and share their memories and thoughts about these two special missions.

For a table with team members' Then and Now images, go here:

https://solarsystem.nasa.gov/50th/stories.cfm?StoryID=283


The Encounter -- Coming in Close

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This distant view of Neptune and its moon Triton was taken on June 20, 1988 as Voyager was approaching the planet for its close encounter in August of 1989. Image Credit: NASA/JPL

The team remembers how extraordinary it was to visit this world:

"We had been lucky enough to be in the right place at the right time with the right team, and this was the first and only opportunity we would have for a long time for an up-close and personal view of Neptune and the outer parts of our solar system." --Ralph McNutt

"It's only possible to do that once every 175 years -- the next opportunity will be in 2152," remarked Stamatios Krimigis (principal investigator of Voyager 1 and 2's Low Energy Charged Particle (LECP) instrument and collaborating scientist for New Horizons).

"The little blue point of light was constantly getting a little bit bigger and bigger, building for months. As we came closer and closer, everything became more and more exciting." said Trina Ray. Trina has been a Voyager Mission team member since 1989 and also works on the Cassini mission to Saturn.

"As much as anything, just seeing this world unfold from the point of light it had been to become a real place was just enthralling," remembers Alan Stern, New Horizons principal investigator, who was a graduate student at the time of the Neptune encounter.

"Seeing Neptune in detail was, of course very exciting. Neptune is so far away -- before Voyager 2 we didn't really have many details about it," said Cassini Project Scientist Linda Spilker. (Linda was an experiment representative and science associate for Voyager.)


The Atmosphere on Lab

The team recalls the exciting atmosphere at NASA's Jet Propulsion Laboratory (JPL) surrounding the time of the Neptune encounter:

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In this image taken (August 25, 1981) during the Voyager 2 Saturn encounter, we see the team members' excitement at reading the incoming data from the spacecraft.

"The team had been working together so long and everyone knew everyone so well and worked great together." --Trina Ray.

"I remember how excited we were to be watching the data come in. The main question was how much magnetospheric plasma were we actually going to see?" --Ralph McNutt

"I remember being very excited, both by the images and science being revealed as we got closer to the planet and by the general excitement around JPL due to the encounter." --Suzy Dodd

"More press would arrive and I remember having to start delivering data twice a day. On the encounter day itself there were many special data requests and hourly deliveries. It was crazy for a first job." --Trina Ray

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A view of the Radio Science Support Team area at JPL. Tom Spilker is fourth from the left and Richard Simpson of Stanford University is seated next to him. Monitoring screens and display selectors (boxes with two rows of push-buttons) are visible. On top of the left-most screen is a plastic basin with a drain in the bottom and two faucets -- a reference to the fact that to conduct a radio science experiment successfully, you have to watch everything including "the kitchen sink."

Tom Spilker who was in graduate school at the time and a Voyager 2 radio science team member, recalls: "I got this overwhelming feeling inside, as if I was standing in the bow of Captain Cook's expedition into the Gulf of Alaska for the very first time. We were going to places where no one had ever gone before -- we were explorers." (Tom is now retired. During his career, Tom served on several missions -- such as Cassini and Genesis -- as well as mission concepts.)

"In the beginning of the encounter it was a nail-biter, because we had to fly over the north pole of the planet so that we could fly by its moon Triton." --Stamatios Krimigis

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Linda Spilker with members of the Voyager team during the Neptune encounter in 1989.

"In keeping with all good flybys (or so it seems to occur this way) this flyby took place during the wee hours. I stayed up all night that night." --Linda Spilker

Ellis Miner, who was the assistant project scientist on Voyager 1 and 2 under Chief Project Scientist Dr. Edward Stone, stated: "I spent the night before the encounter in a sleeping bag in my office at JPL. I had a monitor in there which enabled me to see each of the pictures as they came in." (Miner has since retired and now volunteers as the associate director of the Los Angeles Family History Library.)

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"I'm in the lavender dress. At the times of the flybys, the library would fill up with scientists, post docs, graduate students, reporters, ... hardcopy pictures were scattered everywhere, pinned to the walls, in people's hands. I loved the hustle and bustle and energy! This was taken a day or two after the closest approach -- you can see Hal Masursky puzzling over a picture of Triton." --Candice Hansen
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This image was taken just after the Voyager Neptune flyby. From top left are Candy Hansen, Sue Linick, Linda Spilker and Bob Nelson. The team members' heads are positioned in the same direction as the Voyager instruments (on the scan platform) that each person pictured here represented for the mission.

"Of course all the action was at the JPL that August of 1989. I do remember Carl Sagan calling me at the Goddard Space Flight Center (GSFC) while I was making collaborative measurements of Neptune's moon Triton with the International Ultraviolet Explorer (IUE) satellite; to say: 'Hey, you're not in the thick of it, but let me tell you what the press doesn't know yet.' He did this so I would feel like an insider." --Alan Stern

As a member of the imaging team, Candice Hansen recalls how busy her office area was leading up to the encounter: "In the last few weeks before the day of closest approach the imaging library filled with not only the imaging team, but also their grad students, post docs, colleagues, and the press. The atmosphere was electric with excitement, and every image brought new unexpected wonders," said Hansen. (Hansen is now the deputy principal investigator (PI) for Mars Reconnaissance Orbiter's HiRISE instrument and a co-investigator (Co-I) for Juno. She is also a member of the Cassini UVIS team.)

"The vice president came too. I remember going up in one of the elevators with a woman who was dressed oddly for JPL. She was wearing a white business suit. Later, I saw her on the roof with a rifle -- she was a member of the secret service for Vice President Dan Quayle who was on Lab for the encounter." --Trina Ray

"And to top it off, we had an open air concert by Chuck Berry (of Johnny B. Goode fame) at JPL! I will never forget that day." --Stamatios Krimigis

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Chuck Berry performs on the steps of JPL in celebration of the Neptune encounter. Image Credit: NASA/JPL

The Surprises

Voyager 2's flyby of the Neptune system was not without its surprises:

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Dr. Ed Stone (left) with Dr. Ellis Miner (far right) talk with another member of the team during the Voyager 1 Saturn encounter (November 10, 1980). Image Credit: NASA/JPL
 

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Neptune by Voyager 2. The Great Dark Spot is visible on the face of the planet. Image Credit: NASA/JPL
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An image of Triton from Voyager 2 as it was approaching the moon. Image Credit: NASA/JPL
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A close-up view of Triton. Image Credit: NASA/JPL
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This wide-angle Voyager 2 image, taken through the camera's clear filter, is the first to show Neptune's rings in detail. Image Credit: NASA/JPL

"The Voyager 2 flyby of Neptune was just another example of the surprises we had time after time as Voyager was flying by each of the outer planets." --Ed Stone

"What we found at Neptune differed greatly from planetary scientists' predictions. It was just surprise after surprise after surprise," added Randii Wessen, Voyager Neptune encounter science sequence coordinator. Nowadays, Wessen works on Cassini, Mars Rovers and advanced concepts for future missions.

Great Dark Spot

"The first big surprise was the Great Dark Spot on Neptune. This dark spot is very similar to the Great Red Spot on our solar system's largest planet Jupiter, which is a very large storm. This spot was unexpected: Neptune is six times further from the sun than Jupiter. Due to this distance, Neptune only receives about 1/36th of the energy that Jupiter receives from the sun to drive its atmosphere. Yet, here was a great dark spot." --Ed Stone

Triton

"Probably the most memorable of the events that took place during the Voyager 2 Neptune flyby was the spacecraft's flyby of Neptune's moon, Triton. We expected surprises, but we were not prepared for the bizarre nature of Triton." --Ellis Miner

"Triton was the coldest object that Voyager flew by (38 degrees above absolute zero, approximately -390 degrees Fahrenheit). This is cold, so cold that even nitrogen forms ice. What was so interesting about this flyby, and about the satellite itself, is that even at 38 degrees above absolute zero there were geysers erupting, not water driven geysers, but nitrogen driven ones." --Ed Stone

"Triton didn't look like any of the moons that we had seen previously. That's one of the things Voyager taught us early on: Don't prejudge and to be prepared for surprises." --Linda Spilker

"We found nitrogen geysers on Triton. The idea of geysers driven by a solid greenhouse effect was bizarre." --Randii Wessen

"I mostly remember the transformation of Triton from a dot to a geologic world. And who could forget the appearance of geysers on the south polar cap; that was the most memorable moment for me," said Bonnie Buratti who was a member of the Voyager 2 Neptune encounter photopolarimater science team. Bonnie is now a member of the science teams on both New Horizons and Cassini.

"Triton's huge polar ice cap, the cantaloupe terrain, the dark streaks across the polar ice, and the dark vertical plumes emanating from several spots on the polar cap were all features seen nowhere else in the solar system." --Ellis Miner

"The Triton flyby was my favorite moment partly because it was a bookend. The journey really started with the discovery of volcanoes on Io with Voyager 1, 10 years earlier (1979) -- the first bookend. We finished the planetary part of the mission with another bookend: the flyby of Triton, where we discovered a much colder, smaller world that was also geologically active." --Ed Stone

Ring Arcs

"We knew from stellar occultations that Neptune had these odd looking rings. Were they partial rings? How many rings were there? Ultimately, Voyager revealed these to be a series of four ring arcs." --Linda Spilker

We couldn't wait to find out what we would discover next." --Randii Wessen


Images

The team shares a few thoughts on imaging and some of their favorite images from the flyby:

"Imaging is not the only science gathered by spacecraft. It is, however, one of the dominant ones whose output is something that people love to see. The Neptune encounter was referred to as 'the last picture show' because after the Neptune encounter we were going to turn off most of the optical instruments." --Randii Wessen

Fran Bagenal, who was a Voyager plasma science (PLS) experiment team member in 1989 and who is now a co-investigator (Co-I) for both New Horizons and Juno, said: "As a young professor teaching her first classes of Intro Astro at Colorado University, it was just fantastic to be able to show pictures fresh from the Voyager flyby and talk about the brand new results."

"Receiving each image during the flyby took about five to ten minutes. The pictures would be displayed on little TV screens. I remember people hopping up and saying: 'What do you think that is?' It was a wonderful time: There was plenty of time to point, think about, and analyze each image before the next one came in -- each one seemed more interesting than the next.

 

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This dramatic view of the crescents of Neptune and Triton was acquired by Voyager 2 approximately 3 days, 6 and one-half hours after its closest approach to Neptune (north is to the right). Image Credit: NASA/JPL
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This Voyager 2 high resolution color image, taken 2 hours before closest approach, provides obvious evidence of vertical relief in Neptune's bright cloud streaks. Image Credit: NASA/JPL

We were almost seeing the images in real time. Acquiring the rest of the data from the spacecraft wasn't as much of the instant science you could do with a picture. It took much more of an effort for all of the other instrument teams to put their stories together.

I remember the other teams had to physically generate magnetic tapes and then take them to the airport to ship them. For example with IRIS, we had computers and such here. However, we would have to wait patiently for the tapes, then put the tapes on the machine and then start reading the data and averaging the spectra." --Linda Spilker

"In the earlier days of the Jupiter flybys we were lucky if there were a few low-quality prints available, and only available several days after they were taken. Technology changed quite dramatically over the Voyager journey from Jupiter to Neptune! At Jupiter we used punched cards and magnetic tapes to process the data. By Neptune we were analyzing the data on desk-top computers in real time." --Fran Bagenal

"One of my favorite images from the encounter is the crescent Triton rising next to the crescent of Neptune." --Randii Wessen

"One image that I thought was incredibly striking and which made the encounter 'real' for me was the one of Neptune as a big dark blue marble with a little golden Triton in the corner. It was the first decent picture that had color, and which showed both the planet and its largest moon." --Ralph McNutt

"I especially like the picture that shows both Neptune and its satellite Triton, both as crescents. This image was taken as Voyager 2 was leaving Neptune to embark on the beginning of its journey to interstellar space." --Suzy Dodd

"I liked the images of Neptune showing the Great Dark Spot and "scooter:" this was the little white cloud that appeared to scoot around the larger dark spot. We were surprised to see this level of activity on Neptune due to the fact that Voyager 2's earlier visit to Uranus showed that planet to be very bland." --Bonnie Buratti


The Past -- The Future

Members of both the Voyager 2 and New Horizon's teams consider the two missions on the anniversary of Voyager 2's Neptune flyby:

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Members of the Voyager team at JPL. Image Credit: NASA/JPL

"Voyager's anniversary coinciding with New Horizon's passage of the orbit of Neptune is a wonderful coincidence." --Bonnie Buratti

"My experiences with Voyager long ago taught me that, when it comes to science exploration of the solar system, serendipity generally rules." --Ellis Miner

"Several members on my team (who are now senior or mid-career scientists) were grad students or post docs working at JPL during the Voyager Neptune encounter. I like the symmetry of having a new generation of machine and the new generation of scientists leading exploration." --Alan Stern

"The Voyager saga has been an incredible one. We have a mini-saga with the New Horizons mission: New Horizons is our next big step in exploring our solar system." --Ralph McNutt

"Voyager was a really amazing program and it still is. The team really pushed the spacecraft to get the most science possible. After the last planetary encounters were complete, we looked back and thought, 'Wow, what an accomplishment!' and 'Wow, I was part of it.'

Voyager is a hard act to follow. There are two classes of giant planets in our solar system. There are the gas giants (Jupiter and Saturn) and the ice giants (Uranus and Neptune). Voyager visited every one of these, as well as several moons and rings. However, New Horizons will be visiting another class of objects; a class of objects that have never been visited before: Kuiper Belt Objects (KBO). " --Tom Spilker

"Voyager helped revolutionize our understanding of the ice giants. Much in the same way, the New Horizons Pluto flyby will revolutionize our understanding of the largest Kuiper Belt Object." --Linda Spilker

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New Horizons will be the fifth spacecraft to cross the orbit of Neptune. Image Credit: NASA
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Alan Stern and Fran Bagenal in 1991.

"The Neptune encounter was similar to the likes the last Apollo moon landing ... an end to an era -- and very special, something you wanted to hold on to. Of course, New Horizons is now opening up the next chapter, but there will be 26 years between them by the time New Horizons reaches Pluto." --Alan Stern

"In both cases, in the past with Voyager and now with the upcoming Pluto encounter by New Horizons, we have very little idea concerning what we will find -- they are largely un-explored systems. That makes things all the more exciting!" --Fran Bagenal

"Voyager is a mission that makes me smile. When I was an intern during the Voyager Saturn encounter, I was told that the Voyager mission was only going to last for a total of five years. I always thought Voyager would be over sometime during my professional career. Now, I don't know which will be over first: me or it." --Randii Wessen

"Whenever there is a 'first' in planetary exploration, we are surprised. New Horizon's upcoming encounter with Pluto is a big first -- it completes our inventory of the solar system." --Bonnie Buratti

"I have to say Voyager is my favorite experience at the Lab. I still give Voyager talks. People remember it with such fondness. Dr. Stone has a wonderful quote where he says, 'When you go somewhere you have never been, you are bound to learn something that you never had known.' New Horizons is doing just that. This mission is similar to Voyager in that it is going somewhere we have never been. That always brings excitement. I completely wish the New Horizons team the best and I think it's going to be a great and exciting mission." --Trina Ray

"The Voyager and New Horizons missions have very important similarities. They are both historic missions of exploration to the very frontier of human knowledge: Voyager with the middle zone of the solar system and the giant planets, and New Horizons with the Kuiper Belt and Pluto. Both excite the public about not only the field of planetary science, but also about exploration and some of the things that our nation and NASA does that really do go down in the history books." --Alan Stern


Hopes for Pluto

Team members look forward to the upcoming flyby of Pluto:

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The artist's concept shows the Pluto system from the surface of one of the smaller moons. Image Credit: NASA, ESA and G. Bacon (STScI)
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This image, taken by NASA's Hubble Space Telescope, shows five moons orbiting the distant, icy dwarf planet Pluto. Image Credit: NASA

"The New Horizons flyby promises to be very exciting. What will we see at Pluto? What will be the big surprises? Like the Voyagers we are set to discover a new world." --Candice Hansen

"There's been speculation that Triton is a captured Kuiper Belt object. Pluto is the largest member of the Kuiper Belt and it is possible that Pluto will look a lot like Triton." --Ralph McNutt

"There are major discoveries ahead. Every time we visit a new place, we have been surprised. Some of the most important science we have obtained was science we didn't even know about, and I believe that will happen again when we fly by Pluto." --Ed Stone

"I've worked with Cassini a long time now and I'm interested to know if Pluto looks anything like Saturn's moon Phoebe. I am looking forward to comparing Phoebe to Pluto or one of Pluto's moons." --Linda Spilker

"The big question on my mind is whether Pluto is active or not. It was exciting to see geysers on the surface of Triton. I hope we see something as wonderful as that on Pluto." --Bonnie Buratti

"I am looking forward to New Horizons discovering the unexpected at Pluto. More so, I'm looking forward to getting to understand Pluto as a place after all this time. You know, we started this in 1989, the same year Voyager encountered Neptune, when Fran (Bagenal) and I approached NASA Headquarters with the idea and pitch of: 'Let's get something together for a future mission to Pluto.'" --Alan Stern

"Exciting times are coming. People thought that we would never get anything out to Pluto -- now we have less than a year before we arrive there." --Ralph McNutt


More Information:

The Voyager spacecraft were built and continue to be operated by NASA's Jet Propulsion Laboratory (JPL), in Pasadena, California. Caltech manages JPL for NASA. The Voyager missions are a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate at NASA Headquarters in Washington.

For more information about Voyager, visit: http://www.nasa.gov/voyager and http://voyager.jpl.nasa.gov

New Horizons was designed, built and is operated by the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. New Horizons is the first mission in NASA's New Frontiers Program of medium-class spacecraft exploration projects.

For more information about New Horizons, visit: http://www.nasa.gov/mission_pages/newhorizons/main/#.U_JpXfldV8E and http://pluto.jhuapl.edu/


Editor's Note: If you were a member of the Voyager 2 Neptune encounter team and would like to be included here, please contact us.


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