Space Topics: Voyager
The Stories Behind the Mission: Bud Schurmeier
As Told to A. J. S. Rayl in 2002
on the occasion of Voyager's 25th anniversary
Harris 'Bud' Schurmeier served as the first Project Manager for the Voyager
mission. In 1976, just before the twin spacecraft launched, he became Assistant
Lab Director at the Jet Propulsion Laboratory (JPL).
In November 1985, Schurmeier retired from JPL, but not from his passion for
planetary exploration. He then went on to serve as Project Manager for Mars
Balloon in the 1980s and Mars Rover in the 1990s, two major projects of The
Planetary Society (TPS). Currently, he serves as the head of the review committee
for TPS' Cosmos 1 project, the first attempt ever to fly a solar sail.
"The Voyager mission came into being when NASA cancelled another mission
called the Grand Tour, a very large mission that was to have sent spacecraft
to all of the outer planets, including Pluto. The plan for the Grand Tour
had been to take advantage of a once in every 175 years planetary alignment
and launch four specially designed, identical, Thermoelectric Outer Planets
Spacecraft known as TOPS -- two in 1977 and two in 1979. It truly was a grand
plan. But there were several complicating factors with the Grand Tour.
First, the cost was significant, because the idea had been to install a lot
of new technology, including, for example, a Self-Test And Repair computer
STAR -- that was being developed at JPL. The rationale for the STAR system
was that once the spacecraft got out to Jupiter and Saturn, and then Uranus
and Neptune, the communication lag-would be so great that we wouldn't be able
to do anything in real time, but with this new state-of-the-art computer system
the spacecraft could take care of themselves for at least 10 years. Much of
the technologies and techniques started in STAR have been are being used in
present and planned missions.
Also the scientists had some concerns that the plan to have each of these
spacecraft be identical could limit their mission objectives; they would not
be able to incorporate the results gleaned from one mission into the next.
We also planned to radiation-harden all the components, and add a number of
other technologies that were not cheap but were the next big steps forward
in the effort to explore the outer planets.
Coupled with the cost was the political problem one always has with long-duration
exploratory missions -- anything with more than a four-year horizon is very,
very difficult to get approved because any given Administration is in office
for only four (guaranteed) years and one President doesn't want to pay for
something for which the next Administration will get the credit. That has
forever been a problem in the space program.
Remember too that we were in the era when all of NASA's money was being sucked
into the shuttle program. The shuttle, in fact, proved to be our biggest competitor
for available dollars. In the end, cost and politics led to the cancellation
of the Grand Tour. But it wasn't that the agency didn't want to explore the
outer planets, it just wanted something less costly and ambitious.
At that point, NASA Administrator James Fletcher said to us: 'If you can
design something that you can get the Space Science Board to approve, then
we will propose it.' So we came up with a scaled-down version of the Grand
Tour based on Mariner technology. We had had Mariner Venus, and Mariner Mars
and this one we called Mariner Jupiter Saturn or MJS77 - with the number representing
the launch year. We then made a presentation to the board.
We had confidence that MJS77 was going to get approved, but you never know
until it is approved. The board deliberated and there was some relief when
the word came down. We had put a lot of effort in to making it happen and
that was the first big memorable moment in the project's life. The name MJS77
name was changed to Voyager after the project team voted on it from a list
of names a few months before launch.
Where the buck stopped
As project manager, the primary responsibility in the beginning was to select
and put together the team of key personnel. I had known all the guys from
previous missions and knew their strengths and weaknesses. I got to choose
whoever I thought would make the best person for a particular job and then,
if I could talk them into it, we had a go.
Getting Ed Stone on board was an interesting effort. Robby Vogt {Rochus E.
Vogt} - a professor now at Caltech -- headed up the Science Working Group
for the Grand Tour and had continued on in that capacity with MJS77, determining
what the detailed science objectives should be and what kind of basic experiments
ought to be performed. I got to know Robby very well in that Grand Tour phase.
We commiserated a lot. Once we really got going with the scaled-down mission,
we had to have a project scientist. He said, 'Look I think we ought to get
Ed Stone for that position.' I trusted his instincts.
Ed was a well-known and respected scientist - and being at Caltech he would
be locally available, as opposed to someone from the other side of the country.
We wanted somebody local, and he had the stature we felt was needed to work
with the outside scientists who were going to be involved. But Ed didn't accept
the offer right away. He was somewhat reluctant because he is a scientist
and researcher and he was concerned he would get bogged down with too much
administrative work -- and there is a certain amount of that to be done.
We came up with a scheme wherein we would have a science manager - Jim Long
-- who would work for the project scientist. This science manager would spend
fulltime on the project and serve as the interface between all the project
activities and Ed Stone so that Ed would not have to devote fulltime to the
project scientist role. The science manager could keep Ed informed, attend
all the many meetings, and handle the administrative paper work. That would
allow Ed to continue his work and research at Caltech and at the same time
serve as project scientist. We prevailed and pushed on Ed to accept and he
finally did accept it and the rest as they say is history. That scheme really
worked out great.
As the Project Manager, I was also the one with the ultimate decision-making
authority on most key things - whether we should we spend a little more money
here or put it there. It wasn't that I had all of the smarts to know everything
that went into every aspect of the mission. But somebody has to listen to
all the pros and cons and then make the judgment that this is the way we should
go. The buck stopped with me. Through it all, I tried to listen to all the
smart technical guys and try to separate the b.s. from what was real and then
decide to put the money.
The radiation factor
When we simplified the mission to use Mariner technology, one of the key
decisions was that we would not radiation-harden the spacecraft. That would
save a lot of money and was a key factor in getting the project approved.
We designed the mission on the Jupiter-radiation environment model developed
by scientists from Earth-based measurements. Based on this model, we set the
Jupiter fly-by distance to provide a safe environment for an unhardened spacecraft.
There was a project underway to launch the Pioneer spacecraft in 1972 and
1973 those would serve as precursors and do two things - 1) find out if we
could actually get a spacecraft through the asteroid belt and 2) determine
what the real radiation environment is like. If the Pioneer data showed that
the radiation environment was stronger than scientists had predicted, we could
still have a mission by moving the flyby distance away from Jupiter where
the radiation would fall off. We would be still okay then with the unhardened
spacecraft - at least that's what we thought.
By the time the Pioneer data was returned, however, the design work had been
done for the electronics on the Voyager spacecraft - and -- lo and behold
-- not only was the radiation environment 1000 times stronger, but it did
not fall off as rapidly as had been predicted. If we went far enough away
where we felt an unhardened spacecraft could survive and get out to Saturn,
we just wouldn't have a worthy mission. That discovery forced us to radiation-harden
the spacecraft.
This was a big transient to the project development and we had to do a number
of things to insure Voyager's success. A certain amount of work had been going
on in the country for radiation-hardening electronics mostly for the nuclear
program and the early-warning satellites. We first tried to find components,
such as transistors, that would be radiation-hard but have the same performance
characteristics. That was the easiest solution. Although it was more costly,
but it also meant we wouldn't have to redesign everything. If we couldn't
do that, then we planned on redesigning the circuits to accept some degradation
of the components due to the radiation. And, if we couldn't do that, then
last option was to put on some shielding. As it turned out, we did some of
all three of those things. As I say, it was a big transient, but it worked
out fine. The testament to that is the fact that Voyager is still going out
there.
A sense of pride and accomplishment
By the time the Voyagers were ready to launch, I had moved on, and was in
the role of observer for the encounters. Even so, each of the encounters was
extremely memorable, because each planet and moon was so different and so
many new findings were revealed. We were seeing some of these bodies for the
first time. While we had reasonable pictures of Jupiter from Earth and knew
what that planet looked like, the great details and the pictures of the satellites
were just astounding.
We all knew, too, that Saturn had rings, but their detailed and very strange
character -- these intertwining rings - was completely unexpected. Of course
we had never had anything except for fuzzy spot pictures of Uranus and Neptune,
so seeing those two and their satellites for the first time was just outstanding.
Even though I was not then directly involved in the execution of the mission,
having been involved, I felt a great deal of pride in the whole accomplishment.
Although we started the mission on the basis of an upgraded Mariner, we did
end up putting in a number of new technologies that gave Voyager remarkable
versatility. Part of the reason for that was because at the time this mission
was approved, we still had hopes of proposing what we called JUN - Jupiter,
Uranus, Neptune -- in 1979. We didn't want to have to redesign the whole spacecraft,
but incorporate technology that would be useful for that mission later on.
As it turned out, we never did get the 1979 mission and Voyager ended up
going to all four of the outer planets. The reason those other encounters
at Uranus and Neptune and their satellites were possible, despite the fact
Voyager is based on 1970s technology, is because of those early decisions
and the enhanced, new technologies. We added flexibility into the attitude
control system and the communications system, put new coding into the telemetry
system that wasn't used until Uranus, and installed redundant equipment for
almost all of the electronics. Beyond all that, the engineers had figured
out ways to use these systems in parallel to increase the capability to get
data rates and to provide the great pictures they got out at that distance.
I should also point out that a great deal of the communications performance
at Uranus and Neptune was due to the phenomenal improvements in the capability
of Earth-based communications systems of the Deep Space Network (DSN) and
supporting facilities. Without that, we would have received only a small fraction
of the data that ultimately was returned.
In the end, Voyager was a scaled down mission, but it was still archetypical
big science, the likes of which we probably won't see for a long, long time
to come. Voyager's versatility took us well beyond mission success. The fact
that they are both still going makes all of us feel great."
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