As director of Pasadena's Jet Propulsion Laboratory, Edward Stone has overseen some of NASA's greatest successes and worst failures of the past decade

Edward Stone has been at the forefront of the American space program almost since its inception in 1958. A physicist by training, he came to the California Institute of Technology (which administrates NASA's Jet Propulsion Laboratory) in 1961, and has been the chief scientist on nine NASA spacecraft missions.

In 1991, Stone became director of JPL and ever since has been spearheading the institution's sometimes-rocky transition toward less expensive and more frequent planetary missions. These have included the successful Mars Pathfinder mission in 1997, which put a rover on the surface of Mars, but also the unsuccessful Mars Climate Orbiter and Polar Lander in 1999. He recently announced that he will resign as director next year, after his 65th birthday.

Since in the 1960s, JPL has been developing spacecraft and overseeing missions to explore other worlds, principally other planets in the solar system. One of the most successful of these missions was the Voyager project, twin spacecraft that were launched in 1977 and are still communicating their findings as they travel through space. Stone was the chief scientist on the Voyager project.

Besides heading JPL, Stone also serves as vice president of Caltech and as chairman of the board of directors of the California Association of Research in Astronomy, which is operating the two W.M. Keck Observatory telescopes on Mauna Kea, Hawaii.

He has received numerous honors and awards, including honorary degrees from Harvard University, Washington University in St. Louis, and the University of Chicago.

Question: What have been the most important changes in the type of space missions overseen by JPL under your watch?

Answer: The major change has been the transition from what I call the secondary era of exploration to the third era. In the first era, the main engineering and science challenge was just getting to another planet. That was in the 1960s. It established the capability to get there and set the stage for the second era, where the challenge was to find out what was actually out there. Those were global surveys of everything in the solar system, at least all the major planets and many of the moons. Since we knew so little, that meant that we wanted very large, comprehensive observatories with many instruments.

Q: How is the third era different from the second?

A: At the beginning of the last decade, even as we were finishing Cassini (a probe slated to arrive at Saturn in 2004), it was already clear that we were ready to move on. Now that we knew what was out there, the challenge became, how do we go more often to more places, and go from global to local surveys? Once you move into this third era, you need to be able to go much more often, because you're not looking at things from a distance but on a small scale. That means you need many opportunities, because planets are big and you can't understand, for example, the Earth as a planet by landing at just one place on it.

Q: This brought about the quicker and cheaper missions?

A: Yes, we needed to move to an era of finding ways to do things on much shorter cycle times, at much lower costs. It's also been an era that has been made possible by the revolution in computing and micro-devices, through which we can now talk about doing things at a lower cost and faster.

Q: What's the difference in cost between missions in the second and third eras?

A: The Voyager mission and missions like that were typically in the order of $1 billion and took five to seven years to prepare, with their flight time depending on how far they'd have to go. So we could do one or at most two of these per decade, because they were very complex and expensive systems. Now that we are into this third era, the cost typically is $100 million to $200 million per mission. In fact, the median cost in the early '90s was $600 million per mission, and now we're approaching $110 million per mission.

Q: Does that mean that you can do five times as many missions?

A: Yes, we now go to Mars every two years, instead of once every two decades, which is what we had been doing. We have a mission that is on its way to collect a sample of comet dust. We're also going to be launching a mission early next year to collect a sample of the solar wind, so we can actually find out what the sun is made up of. These are the kind of things you can do once you get the cost of a mission down to the $100 million range.

Q: But there has been criticism that the less-expensive missions have resulted in more failures.

A: We were obviously learning what the limits were. Mars Pathfinder, which landed very successfully on Mars on July 4, 1997, was one of these new-era missions. But before this mission was completed, we had set ourselves the task to do two missions for the same price as Mars Pathfinder, which was the Mars '98 project. We were trying to find out where the boundaries were to lower costs and faster cycle times. It is clear in retrospect that that was too big a leap. Mars Pathfinder was doable, but doing two, an orbiter and a lander, for the cost of a single lander was just pushing too far. Now we're restructuring the Mars program to make sure that we're more in the Mars Pathfinder class of funding rather than at half of that.

Q: Has there been any problem securing federal funding for space programs in recent years?

A: Actually, the space sciences budget at NASA has been growing modestly over the last several years. That's within a NASA budget that unfortunately has not been growing. This year, for the first time, the president has asked for a modest increase in the NASA budget, and we'll have to see how it comes out in Congress.

Q: There seems to be less enthusiasm for space programs nowadays than there was in the past. Does that explain the slow growth in funding?

A: It's hard to understand the dynamics that affect the total NASA budget, but the space sciences budget has actually been growing. And when Mars Pathfinder landed on Mars, in one month we had 565 million hits on our home page it was a world record at the time by a large margin. That's clear evidence that there is still public interest and engagement in the exploration program.

Q: Aside from the obvious scientific discoveries that result from the space missions, what are some of the more practical benefits we have seen?

A: The technology that has come of the missions has found many practical applications. Digital imaging, for example, was pioneered here (at JPL) in the '60s and is now found in every desktop computer. Digital communication was also developed here in the '60s, and today digital cell phones are everywhere. More modern examples would be a very sensitive receiver we developed to use with global positioning satellites for tracking spacecraft. We realized that if we put one of these receivers at Palos Verdes Hills and one at JPL, we could measure a change in distance between those two places to a 16th of an inch. Now, we're in the process with the Southern California Earthquake Consortium at USC to put in place 250 of these receivers around Southern California, which will enable us to see for the first time the motion and the buckling and the distortion of the Earth's surface between earthquakes.

Q: Is promoting technology transfer, spinning off commercial applications of the technology you develop here, an important part of JPL's mission?

A: Yes, JPL is run by Caltech, and as a result the intellectual property we develop here is licensed through Caltech. We have certainly been much more proactive in the last five years, in terms of trying to create opportunities for small companies and also for large companies to take advantage of the technologies we develop.

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