A.J.S. RaylSep 05, 2002

The Stories Behind the Voyager Mission: Bud Schurmeier

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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