THE POPE SAID “WOW”

It may not have been until his audience with the Pope in January of 1997 that interplanetary mission director Bill O’Neil truly realized the full magnitude of his accomplishments. As project director of the ambitious Galileo probe to Jupiter, O’Neil had spent most of the previous two decades confronting, and methodically overcoming, some of the most complex technical challenges ever to have occurred in the history of space-flight. At every stage, this chain of mishaps was finally transformed into triumphs. And, in a kind of alchemical transformation, most of the problems encountered by Galileo actually ended up benefiting the mission in unexpected and important ways. (They also benefit us: many of the technical break-throughs that were necessary in allowing distant Galileo to communicate with Earth using its low-power secondary antenna are currently in use in both the data-compression software and signal-processing hardware of personal computers and global telecommunications systems.)

In the end, Galileo is now known for its many successes and firsts. Galileo was the first space probe to enter orbit around one of the huge outer planets. It was the first, and so far the only, to engage in a complex tour of a planet’s multiple moons (we will see more of this when NASA’s Cassini mission reaches Saturn’s archipelago in a couple years). It was the first to drop an atmospheric probe into the atmosphere of an outer planet. Among the spacecraft’s many scientific achievements is the determination that Europa, one of Jupiter’s four largest moons, may actually contain a liquid water ocean under its icy surface. It was the strange cracks and trapped icebergs on Europa’s frozen face that caused the papal exclamation quoted above.

-- Michael Benson

Q: So let’s get to your arrival at Jupiter. You’ve solved the communications problem as best you can, and the atmospheric probe and the orbiter are flying side by side as you enter the Jovan system. The probe plunges into Jupiter’s atmosphere, and remarkably, it turns out that by some fluke it has ended up in a particularly dry part of that atmosphere.

A: Well, the entry point at Jupiter was pot-luck, in terms of the atmosphere. We knew geometrically exactly where we had to go, but we didn’t know what part of the atmosphere…

Q: You didn’t know what the atmosphere would be doing at that time.

A: We knew the latitude and longitude, but as you say, we didn’t know what the atmosphere at that latitude and longitude was doing, at the time we entered. So it turned out to be a very dry region, although at the end of the useful data, near the bottom of the descent – and by the way, the probe mission was one hundred percent successful, per its plan. We lost nothing, there was no data compression issue or anything, we got all the data back unadulterated, unabridged, we got everything – and at the end of the descent, where the design requirement was 10 bars, we actually got to 21 bars pressure depth on Jupiter. And in the last few data points, the instruments were finding more like what one would expect in water content. And then, over time, Galileo’s near-infrared spectrometer, as it did global imaging of Jupiter for water and other chemistry, found that indeed there are these dry spots. So it was all found to be consistent. In the end in fact we simply went into a dry spot, and it was found that there was probably a thermal upwelling that dried out the atmosphere.

Q: Speaking of water, let me jump to Jupiter’s moon Europa. Are you one of the people who believes that there’s a high chance that there might be life there?

A: I think there’s an excellent prospect. And perhaps even a better prospect than on Mars. But the Galileo mission was frankly never about life detection. Because there was never any expectation of it, of extant or extinct life in that system. Mars was always the front-runner for that. So the prospect of extant or extinct life on Europa is undoubtedly the number one discovery of Galileo. I mean, that could be a speculation, but you know there really wasn’t even any speculation about that before Galileo.

Q: Well, as I recall, Europa looked like a frozen cue-ball, from Voyager.

A: Yeah. An interesting aside, by the way, is that in the original mission plan – the government plan for Galileo when it was approved as a mission – there are no encounters with Europa or Io.

Q: That’s strange. Oh, because that’s even before any volcanoes had been discovered on Io.

A: Right!

Q: So it was just kind of, ‘the Galilean satellites, let’s look at all of them.’

A: Necessarily the foundation of the tour was two passes of Ganymede and then a pass of Callisto. Because, this is a subtle point, but when you come into the Jupiter system you’re generally not in the equatorial plane where the satellites are. So when you arrive at Jupiter you can set up the geometry to encounter one satellite. And that means that there are two places where you’re crossing the orbital plane of the satellites but only one place where you’re crossing at the distance of a satellite, as long as you’re inclined to the plane of the satellites. So what we determined early on in the design process is that we had to do two sequential encounters of Ganymede, the first to bring the period down and the second to snap the inclination into the plane of the equator. You couldn’t have two different satellites for the first two encounters, they had to be the same satellite. So we used Ganymede, which is the most powerful one because of its distance, its speed and its mass.

Q: Ganymede being quite big.

A: It’s the biggest. And then Callisto was used. So and then after that, after the second Ganymede encounter we were essentially in the plane of the satellites, and from then on it was just a matter of adjusting the period of the orbit to rendezvous with the different moons.

Q: Ok. By now you knew that Io was very interestingly volcanic because the Voyager images had been analyzed, and eruptions had been seen in them. But what about Europa? It became clear fairly early on that you should focus on Europa. Or how did it work?

A: No, Europa was kind of in the running along with the rest. But probably at the time when we finally started doing this mission at Jupiter, Callisto was probably the weak sister, the least interesting at that point. But Europa wasn’t discovered to have a high potential of a sub-surface liquid water ocean until the Galileo imaging.

Q: So what year would it be that it started to dawn on everybody that there was such a probability?

A: Well, it wasn’t dawning, it was seeing the images, there was an immediate realization of that probability. And that was in ’96. The Europa encounter was in December of ‘96. The first one of Ganymede was in June of ’96, or July. I remember this because when we were going to show the Pope the album, we had that image, that was the key image, of the icebergs on Europa. And that presentation, the audience with the Pope, was in January of ’97. In fact, we had the conference in Padova the days of the nights of the year that Galileo [Galilei] discovered the satellites. It was actually that week in January when Galileo discovered those satellites.

Q: How did that Papal visit happen? Was it because of Galileo? Who arranged it?

A: Well, my counterpart at the University of Padua, professor Cesare Barbieri, was at the time, from the early 90’s on, also a Galileo project manager. And what brought Cesare and myself together was that we had a common title: we were both Galileo project manager. But the Galileo project Cesare was running was the new Italian national telescope being built on the Canary Islands. A huge telescope in cooperation with Spain, who owns the Canary Islands of course. So it was he who initiated the first contact, and he wanted to promote this concept of three Galileo’s, because of his residence in Padua, where Galileo taught. And it was in the summer of ‘95, in my living room in California, when we invented the ‘Three Galileos Conference.’ Which was the opportunity, at that timely part of the year, to get the scientists together from both the astronomy community and the Galileo spacecraft project community to talk about Jupiter and the Jupiter system. And it was his idea entirely and exclusively, and his promotion, that caused us to have the closing of that conference, which began on a Monday, on Saturday at the Vatican. So we all trained from Padova on Friday night, following the sessions of the conference, down to the Vatican. And met with the Pope the next morning.

Q: And how many people met the Pope?

A: A hundred. But [Galileo project scientist] Torrence Johnson and Giessuri and I essentially had a more intimate interaction with the Pope. Torrence and I presented him with an album from Galileo.

Q: So, what did he say to you? You explained what he was seeing in the album, specifically Galileo Europa images…

A: Yes, and he actually said ‘Wow.’ I mean that was the word he used. That was his response.

Q: Speaking of those pictures, can you describe a few of the scenes, snapshots as it were, of when you discovered various things in the Jovan system? Were you sitting in a large room with a screen, or something like that?

A: Oh, it’s much slower.

Q: Because it’s line by line, isn’t it? Since you have to store everything on that tape recorder?

A: Oh yeah, it’s worse than that. Literally it took months to get the data back from an encounter with a moon. It’s very slow. And even once it’s in the hand it takes quite some time to analyze it, scientifically, and reap the benefits of the information. That stuff comes slowly, so there wasn’t any of this ‘Voila!’ stuff, instant gratification, there wasn’t anything like that. But I remember one of the first images we got of Ganymede in that first encounter was just spectacular compared to the corresponding Voyager imaging of the same area of Ganymede. And of course, superimposing our own images over those Voyager frames just showed that step forward. It’s dramatic. So there was that.

Q: Let’s proceed to Mars. You left Galileo after the primary mission to work on those so-called “cheaper faster better” missions to Mars, right?

A: No, I didn’t leave to do that. I wanted to get involved in the development of another project, since Galileo development was truly finished and we had executed the primary mission. So from my career standpoint, there was nothing for me to gain by staying around. And there was everything to be gained by moving on, particularly so that my proteges, the people in line behind me, could move up and take over. Bob Mitchell did, he’s now Cassini project manager, and Jim Erickson became his deputy, and he became a project manager, and now there’s still another one. So I thought it was very important, and I wanted to do something else. I had kind of grown stale on it, it was kind of anticlimactic at that point.

Q: Yeah. It was a lot of years.

A: So I had to move on. But it wasn’t to go and do the ‘better faster cheaper’ projects, which I’m not completely enamored of. I still contend that the flagships really deliver more return on the investment than the ‘better faster cheaper’ ones. I think one successful flagship mission is cheaper than ten ‘better faster cheaper’ ones, and produces considerably more return on investment, provided it works. The move to ‘better faster cheaper’ I think was largely motivated primarily by not wanting to have all the eggs in one basket, if you will.

But be clear that my main reason for going to the Mars program was my interest in being manager of the Sample Return project. Which was the next, and in fact one of the last big ‘firsts’ in solar system exploration. So that was my motivation. And it turned out, at least at the beginning, that it all worked fine. I got the assignment when it became available. And we were off and running, we did some great stuff, and designed an elegant mission for the sample return, in the year and a half that we had before we got the rug pulled out because of the ‘better faster cheaper’ Mars ’98 failures.

Q: If the Sample return mission wasn’t one of the ‘cheaper, faster’ missions, why did they have to cancel it simply due to the failure of some of those? You must have been furious.

A: Well, I was totally dismayed. Why did they have to cancel it? Because we had these two major failures that compromised our credibility. And this Mars sample return is arguably the most difficult robotic mission ever performed. In fact the fellow who ran the Apollo program, I brought him in to review some materials we were working on for the sample return mission in the first year of the project’s existence. And ever since that meeting I’ve had a quote of his on my wall. And that quote was, “Well, if you think about Apollo, this one is equally complex.” I think it’s an overstatement, but still it gives you the idea that this one was really tough.

Q: Let’s move to the bigger picture, because obviously we have to wind down. It’s 2001, the year of Kubrick and Clarke. When you look back at this whole period, the period since the early days of space exploration, are you a bit disappointed about the amount of support given to space exploration in the last few decades? Do you feel that that initial promise just wasn’t realized?

A: Oh, absolutely. And in fact I can tell you that, oh, about seven years or so ago now, Carl Sagan was at the lab. I knew Carl fairly well from Viking. The team was as I said badge-less, and we all worked together. And Carl was giving a talk in our main auditorium at JPL, on the subject you just touched on. And I put a question to him, I said ‘Carl, I’m distressed that, 25 years ago I would have thought it would be impossible to forecast where we would be, 25 years hence. Because of technological break-throughs.’ And I said ‘With the exception of computing, we haven’t had any, to speak of.’ It’s amazing how little. I mean if you look at the progress since the invention of flight in 1903, to modern-day aircraft, it’s phenomenal. Or even just from there to the Second World War, I mean, the progress in aviation. And if you look at Glenn, and Apollo in ’69, and look at what we’re doing today, it’s pathetic. It’s pathetic that we haven’t done more.

Q: Why, do you think?

A: Why? Because there’s no mandate. And ironically, with the end of the cold war… We wouldn’t have had Apollo, probably, except for the Cold War. And people still would not have been to the Moon, if there hadn’t been the Cold War.

Q: Speaking of which, what’s your opinion about the disparity in budgetary priorities between missions with a crew on-board and the far cheaper robot missions that explore deep space? It’s a widely held opinion among scientists that the former tend not to really produce much worthwhile science return.

A: It’s not a good science investment. And I used to be very strongly opinionated about this, saying that any of the science you want to get, we can get ten to a hundred times more by doing it robotically. But as I get older I realize that humankind has to explore. And ultimately the people have to go. And so we have to accommodate, and realize the importance not just of getting the science but also of extending human-kind to these places. So we need both, and we need to balance it carefully. And I think it has probably been out of balance.

And in the case of the robotic missions we have objectives – we want science questions answered and we figure out the mission to answer those questions. On the human side, the piloted missions, I think it’s more ‘We want to do this, with humans, and what can we get out of it? Given that we’re going to do this, now what can we get out of it?’ Well, we’ve got to try to move those two things closer together.

Q: Lets return for the moment to Galileo. The probe’s mission will end in 2004 with a dramatic plunge into the Jovan atmosphere. Why a suicide at the end?

A: I was not involved in that decision at all. I only recently learned of it myself. And I know the answer to the ‘Why?’ It’s to ensure that it can’t possibly hit Europa at any time in the distant future. We want to ensure that we don’t bring Earth life to one of these primitive bodies, so that we would never know – if we once discover life there, or remnants of extinct life – we’d never know whether we brought it, or it was there before. So that’s the reason: to protect Europa until we can get there with the instrumentation that will tell us the real answer.

Q: How much longer could Galileo have theoretically continued gathering science, beyond that date when it’s supposed to go into the Jovan atmosphere? How much longer, from today, could it continue?

A: Oh, certainly not ten years. Probably not even three. And it could be, as we’re speaking, the propellant could be exhausted.

Q: You know, I have to say, it was really great talking to you, and I really want to complement you on your achievements. Because I know that you probably don’t hear that very much. But there are a lot of people who have been watching, in amazement, these achievements. And I think what you and your colleagues have accomplished is remarkable, it’s just astounding. And I hope you’re appropriately proud of yourself – you should be.

A: Thank you for the compliment. One of the things I do intend to do in this sabbatical is reflect on those accomplishments.

Q: Maybe you should write a book, did you think about it?

A: It’s crossed my mind. But I really want to take the time, to go back, and enjoy what I couldn’t enjoy in the execution. Because there was just too much pressure, and too many demands to really enjoy it.

Q: That reminds me of what the astronauts said when they came back from the Moon: that they just didn’t have the time, they were too busy to let it really sink in. To let the fact that they were actually there – that they were standing on the Moon, and looking up at the distant Earth – sink in.

A: [Smiling] I’m going to let it sink in.

Ljubljana, Slovenia
March 2001- (revised October 2003)