JPL Story "Voyager -- the Journey of a Lifetime" by Dr. Ed Stone

Retold by Barbara Amago

As usual the Library service area transformed itself in a short time
from a quiet area for study into a bustling auditorium. At 3 o'clock
library staff were finishing setting out the chairs and laying out the
programs. Several people showed up early to stake out good seats,
including two people from NASA Headquarters doing a story for *ASK*
magazine \[http://www.appl.nasa.gov/knowledge/ask_home.htm\]. By 3:50
everything was ready, and Story Coordinator Teresa Bailey wondered, "Is
Dr. Stone here, yet?" "He's outside at the picnic tables," Mickey
Honchell answered. Within minutes Dr. Stone appeared, looking relaxed
and ready to tell his story. As the last of the attendees were finding
their seats and library staff turned on their tape recorders and video
recorders, Teresa stood and began her introductory remarks. After a
couple of announcements, she launched into the introduction of Dr.
Stone.

"As you all know," she said, "Dr. Stone has served as Voyager Project
Scientist since 1972, coordinating the efforts of 11 teams of
researchers." But, rather than reciting all of Dr. Stone's many
accomplishments, she referred those interested to the Library, Archives,
and Records Section's online exhibit, "[Faces of
Leadership](http://beacon.jpl.nasa.gov/exhibits/directors/page1.html),"
\[http://beacon.jpl.nasa.gov/exhibits/directors/page1.html\] where they
could read all about him, "all kinds of information about Dr. Stone \--
all the papers he's ever written, where he was born ...." The audience
laughed as Dr. Stone worked his way to the front and clipped on the
microphone.

"It wasn't too long after I stepped down as Director that Teresa was on
the phone asking me when I was going to do a story, but I put her off,"
he laughed. "I've been very busy, actually. But with the 25^th^
anniversary of Voyager, it made sense for me to come up and talk about
some aspects of my own experience." He told the crowd that his story was
going to be more of a personal reminiscence than a history of the
project -- he has other talks planned that will cover that. "This is
more of a personal view of Voyager."

"Voyager has become the icon of interplanetary missions. It saw more new
worlds for the first time than any mission ever has." Voyager was an
incredible journey of discovery. One of the things that made it so
exciting was that all these planets and moons could have been the same.
But what we found was that "nature was incredibly inventive in the way
it used the basic laws of nature to create these diverse, distinct
worlds."

"This story will highlight some of things I learned over the first 30
years as Voyager Project Scientist," he said. In 1972, when Bud
Schurmeier invited him to become Project Scientist, he knew he had a lot
to learn, but didn't realize how much. Project management, public
outreach, all of these were new experiences for him and were part of the
reason it was so interesting. Dr. Stone had been at Caltech since 1964
and flown his thesis experiment on Discoverer 36, launched in 1961. He'd
helped set up a new space physics laboratory at Caltech. In his prior
experience, he had been involved in only earth-orbiting missions that
made a few discoveries each year. New discoveries came in at a steady
pace, and that's kind of how it was on Voyager after we first launched.
Then the Jupiter encounter \-- "The flood turned on," he said. "As we
approached Jupiter, the rate of discovery far outpaced our ability to
comprehend." He wasn't prepared for the volume of new discoveries, and
each day got better and better. It was a remarkable, intense period of
discovery that they really weren't prepared for.

Dr. Stone gestured excitedly as he recalled Voyager's closest approach
to Io on March 5, 1979. Two months prior to the closest approach,
everyone was prepared to see something pretty exciting. A colleague,
Stan Peale predicted that tidal heating of Io's surface could well melt
the interior. "Pretty exciting!" Book 15 of Dr. Stone's project notes
(he's now working on number 40) includes some predictions about how much
heat would be coming out of Io. Rudy Hanel, who had the infrared
instrument that measured temperature, and Dr. Stone sat down and
calculated how much heat would be generated. Here, Dr. Stone took out
his notebook and read his notes. "We calculated 5 microwatts per square
centimeter. I don't know if that was right, but that's what we
calculated," he said. But how much heat came from the Sun? About a
milliwatt per square centimeter. It would have been impossible to
differentiate the small amount of tidal heating generated on Io from the
much larger solar heating of the surface.. Several days before closest
approach to Io, Rudy said there were only three ways to explain the data
that were coming in: 1) there was some very peculiar mineral which
creates this peculiar measurement, 2) we had a calibration problem with
our instruments, or 3) there were, in fact, different temperatures on
this little body. "Nah! That didn't sound reasonable!"

But only a few days later, as the spacecraft got closer and closer,
scientists continued to speculate on the reasons for the unexpected
measurements that were coming in. Could there be an instrument
calibration problem? No matter what the instruments were telling them,
they just could not break out of the mindset they had that "we could not
think of a world with active volcanic calderas on it." But, of course,
as they got closer, it was, in fact, clear that rather than coming out
uniformly over Io's surface, the tidal heat was coming out of the dark
spots on Io that were hot volcanic calderas.

Other amazing discoveries that Voyager made continued to astound
scientists. Liquid water beneath Europa's icy surface? Spokes in
Saturn's rings? The size of Titan? We thought Titan was the largest moon
in the solar system, larger than Mercury, but it turned out there was an
opaque haze layer 200 miles above the surface that made Titan look
larger than it is. "Even when we thought we knew something, we were
wrong!" Dr. Stone exclaimed. Winds on Saturn five times faster than on
Jupiter? "Time after time, no matter what we thought we knew, nature
surprised us!" Some of the phenomena that Voyager discovered have still
not been adequately explained. Miranda, an incredibly complex surface, a
small moon that should have frozen and died, lived on geologically for a
period. Triton, spewing geysers, even though the temperature was only 38
degrees above absolute zero. Those are just a few examples of the flood
of information that continued to come in.

"So, how did a Caltech physics professor get to be Project Scientist for
such an extraordinary mission?" he asked. "That is an interesting
question." There was a mission called the Grand Tour, about a \$1
billion mission, that the Administration cancelled in December 1971. The
Grand Tour was to have visited all the outer planets and last 12 years.
Within a few weeks of the cancellation, Bud Schurmeier's team came back
with a plan to build a Mariner-class spacecraft that would be designed
for a more modest four-year mission to Saturn. It would push the
envelope on the Mariner spacecraft for about one quarter the cost of the
Grand Tour, but with no plan to go on to Uranus and Neptune. "I wasn't
interested in full-time," Dr. Stone said. Bud Schurmeier's decision to
ask him to be Project Scientist was rather bold, since he had never been
on a planetary mission. (Although his knowledge of radiation belts came
in handy later on in 1974 after Pioneer 10 flew by Jupiter and found
that the radiation belt was 1000 times more intense than we expected.)

Dr. Stone asked himself, "Was this role as project scientist something
that compelled me?" Well, Bud kept at it, and he was also encouraged by
the President and Provost that this was important for the Institute,
"and that helped," he laughed. Dr. Stone finally agreed. Here, Dr. Stone
took out a 1972 memo he received from Bud Schurmeier formalizing his
appointment. The memo \[hyperlink to scanned copy\] enumerated seven
specific tasks:

1)  Make scientific judgments for the Project;

2)  Be the overall scientific spokesman for the Project;

3)  Participate in Project activities to continually keep finding and
    recommending ways to maximize the science return from the mission;

4)  Organize and direct the SSG (Science Steering Group) so that it is
    an efficient and effective element of the Project;

5)  Organize and direct the science activities of mission operations;

6)  Develop, negotiate, and manage the science aspects of the contracts
    with the investigators;

7)  Assist in the development, negotiation and monitoring of the
    interfaces between the investigators and the various elements of the
    Project to assure effective working relationships.

Dr. Stone laughed, "All of this was going to take one and a half days a
week!" There was also an "escape clause" which said, "Clearly, there are
many other factors which might cause either of us to feel the
arrangement is not satisfactory including the possibility that the 30%
time commitment is inadequate." This was an experiment -- one that
turned out to be very successful, but we didn't know that at the time.
An assistant project scientist, Lonne Lane, was appointed, and, later
Ellis Miner came on board. Without this group, it would not have been
possible.

Well, Dr. Stone decided to do it, because he was going to learn a lot,
it was clearly important for the Institute, and Bud Schurmeier was great
to work with.

All seven of these tasks were important, "but let me just focus on two
of them," Dr. Stone said, "decision making and being a spokesperson for
the project."

# Decision Making

#  

"Think about the challenge" he said; there were a couple hundred experts
on the project. Conflicts are inherent. No one was an expert on
everything. The PIs are selected by NASA and given a franchise. Science
is about discovery, and decisions are about what gets discovered and who
gets to discover it. "People feel [very]{.underline} strongly about
that!" The challenge was how to do it right. One approach would have
been to take a vote, but that was an easy way out and wouldn't
necessarily have maximized the overall science return. Someone needed to
optimize the science as a whole. To do that, Dr. Stone had to learn a
lot. And a key factor, he found, was "you had to listen." He started
keeping notebooks because he recognized that it was a historic mission,
but it was also valuable because people understood he was really
listening when he was making his notes. "You can never reconstruct what
you thought you knew after the fact, because everything changed," he
said.

As a result of this collaborative approach, "a lot of decisions were
made without a lot of conflict." People were able to see the whole
picture and optimize the science as a whole, rather than just their own
experiments. Some choices were easy, others were more difficult.

One example was the Voyager 2 trajectory at Jupiter. We knew it was the
most hazardous part of the journey. We knew we had to get to Saturn, but
we desperately wanted to get to Io, too, deep inside Jupiter's intense
radiation belt. We could fly Voyager 1 closer to Jupiter, but we had to
keep Voyager 2 further away where it was safer. Then the challenge was,
what are you going to do with Voyager 2? It came down to two
possibilities. Search for an atmosphere of Ganymede by watching the Sun
set as we flew behind that moon, or fly close to Europa, the only large
moon that would not be seen in close up by Voyager 1. "It was apples and
oranges." The decision was to fly by Europa to complete the survey of
the four largest moons.

There was a similar tradeoff at Saturn; one of the primary objectives
was the occultation of the rings, using the radio beam from the
spacecraft to measure their thickness. To do that, we had to fly behind
the rings in a particular geometry. There was one simple way to do it,
and that was to fly diametrically behind the rings from one edge to the
other. The other primary objective was Titan, but flying diametrically
behind the rings meant that the Titan encounter would occur after flying
through the plane of the rings. That put the observations at risk
because of the unknown hazard of unseen material in the ring plane. In
addition, we had to fly by Titan's dark side, which wasn't good for
imaging. Ultimately, working with Len Tyler we found one other way to do
it -- to go by Titan first, then fly behind Saturn and get just half of
the rings. Not as nice as getting the entire ring diameter, but quite
successful.

At Triton we were going over the top of Neptune and down behind Triton
to detect its atmosphere. UV was good for measuring the thin part of the
atmosphere and radio was good for the thicker. The UV measurement
required that we observe the Sun disappear as it entered Triton's
shadow, while the radio measurement required that we fly behind Triton
as seen from Earth. As a result, the trajectory that was perfect for one
put the other at some risk. Instead, we went down right in between the
two optimum trajectories to try to get both, accepting a small risk that
we might miss one of the two. Neither investigator fully agreed, but
they accepted this approach. That was the key. In this case, the Project
"pulled the rabbit out of the hat" and we got both measurements.

Another interesting result of this collaborative approach was that it
really created a [team]{.underline} out of the SSG, rather than just a
group of principal investigators focused mainly on optimizing their
individual investigations in competition with the others. The way we did
it was an open process, and they all were able to see all the issues.
There was a lot of learning going on, on everyone's part.

So, there were three different kinds of decisions: one where we had to
make a choice between objectives, another where we found an alternative,
and a third where we were able to do both.

**Being a** **Spokesperson**

This was bigger than what Dr. Stone had imagined. He imagined talking to
the science community, to NASA Headquarters, and to the public, but what
was really unexpected was all the media attention. During the Pioneer 10
encounter with Jupiter in December of 1973, he was astounded that there
was an auditorium full of reporters every day wanting to know what the
Pioneer investigators were learning. And Dr. Stone realized early on
that this was a unique opportunity to engage the public in the sense of
exploration and the scientific process. But one challenge was that
you've got to help the reporters tell their story; so you can't just
stand up and talk without some preparation. The other challenge was how
to peer review science that was "real time." Every afternoon the day
before a press briefing, all the members of the science team that were
interested got together for a peer review before releasing the reports.
All the team members heard and could comment on what the investigators
wanted to say, and Dr. Stone decided which ones were ready. Then they'd
sit down and design graphics to help explain what had been discovered or
learned, and the graphics were vended out overnight to be ready for the
10:00 a.m. briefings. These science meetings also "broke open the stove
pipes," with people talking between the science teams, and that made the
overall science much better.

He also organized backgrounders to explain things, like a Planetary
Science 101 for reporters. The reporters were excited; they wanted to
see if they could discover something in the images. The reporters were
glued to their televisions. "Remember," said Dr. Stone, "this was a
real-time mission." You had to either be here at JPL or at one of the
planetariums around the country where the images could be viewed as they
came in. We had a story that built on itself over 10 years -- that was
an incredible advantage. That helped make Voyager a major success with
the media and the public.

When the project was designed, there was, in fact, no way to go on to
Uranus and Neptune. The reason why is very interesting. It was because
the project had to end by June 30, 1981, the end of the fiscal year at
that time. As a result, the Saturn encounter had to occur no later than
that, and the aim point for continuing on to Uranus would have been
through the rings. Also, NASA and JPL were planning Mariner Jupiter
Uranus 79, a follow-on mission to Jupiter and Uranus, so there was no
urge for Voyager to aim for Uranus. But in the fall of 1975, MJU79 was
cancelled. The main reason for the cancellation was that the Titan
launch vehicle was being phased out in favor of the Shuttle. As a
result, they requested us to plan for MJX for Voyager 2 (where "X" was
either going to be Titan or Uranus). To allow for this option, we
delayed our arrival at Saturn until August, 1981, so that the Uranus aim
point was outside of the visible rings.

Meanwhile, Pioneer 11 was planning its September 1979 Saturn encounter
and looking for something that Voyager wasn't going to do better the
following year. They wanted to fly inside the rings, even if it was a
suicide mission. Dr. Stone wanted them to fly through the same spot in
Saturn's ring plane as Voyager 2 would have to in order to continue on
to Uranus. NASA's Tom Young, head of the planetary program at NASA,
agreed, even though this was not a popular decision within the Pioneer
project.

# Conclusion

MJS started as a four-year mission to Saturn. "If it had stopped there,
it would have been incredible, but it didn't stop there," exclaimed Dr.
Stone. More software was designed, Charlie (Kohlhase) generated still
more trajectories, the DSN antennas were enlarged, and we kept going on
to Uranus and Neptune. It became a 12-year mission. Its launch window in
1977-79 happens only once every 176 years, so that a single spacecraft
can fly by all four planets. If this window had occurred in 1965-66-67,
we wouldn't have had the technology to fly such a mission. If it had
happened in the 80's, we couldn't have launched the mission. We were
indeed fortunate that the launch window was open at just the right time.
Twenty-five years later, we still have enough electrical power for
another 20 years. "And the journey of a lifetime's not over yet!"

Dr. Stone answered several questions, about mission sunset (Dr. Stone
may be flying to Washington again if they decide to end the mission
before the power runs out); about the heliopause (Voyager hasn't passed
it, yet, but there are several theories about when it will); about
better-faster-cheaper missions (we don't really need another Voyager
mission to fly by the four giant planets -- future missions will
probably send orbiters to the individual planets). And then the story
was over, and the crowd filed out of the Library, a few stopping to ask
Dr. Stone more questions.

To view the planetary images that Dr. Stone referred to during his talk
or for further reading about the Voyager Project, please go to the
Online Exhibit at \[Link to Voyager Online Exhibit\]. To view a new web
video of Voyager's planetary encounters and its continuing journey to
the edge of interstellar space, please go to "[Voyager - the Great
Adventure Continues](http://voyager.jpl.nasa.gov/)" at
http://voyager.jpl.nasa.gov.