Steve Larson, on the discovery of co-orbital satellites around Saturn

We were on the ground observing with the 61-inch telescope in the Catalinas, which was funded by NASA specifically for high-resolution imaging for the Moon and planets, as well as developing other instrumentation for infrared work.

After Kuiper had died, Brad Smith came over from New Mexico State University and he was Principal Investigator of the Voyager mission. He had been pushing for the application of charged-coupled device, CCD, cameras at the telescope. They were still very crude and under development, and they weren’t quite ready for flight time on spacecraft.

But we did get to use a prototype that had been developed for the Hubble Space Telescope, and observed Saturn during the 1980 ring plane crossing. It occurs roughly in 14-year intervals. If you’ve seen Saturn’s rings, they look tilted, but as the Earth goes around and Saturn goes around, they’ll be a period of time when we’re right in the plane, so the rings just look like a thin line. Because of that, there’s less light scattering, so we can look for inner moons and other phenomena that you wouldn’t normally see.

We were following up on what had been announced as the discovery of a satellite, based on data taken in 1966 with a 61-inch during a previous ring plane crossing. There was indication that there might be another satellite, very hard to see because it was faint. But we had looked at all the 1966 data and came to the conclusion that there was a new satellite orbiting very close to these rings.

Well, as it turned out Pioneer 11 flew by Saturn just about the same time we were observing it. Its camera was not capable of taking pictures nearby, because things were flying by so fast, but it sensed something that blocked some of the charged particle radiation that was in the magnetic field of Saturn. We didn’t know what it was at the time. Later it would establish that it was the wake of the satellite that we thought was there, and observed later in 1980. We were watching a satellite that we expected to see coming out of one side. It was called Janus.

And then we saw one on the other side come out.

It turned out, they had about the same orbital radius. This was the first existence, the circumstance of observing two satellites that were in essentially the same orbit. They’re called co-orbitals. We named the co-orbital Epimetheus.

It was a thrill to be at JPL during the Voyager encounter of Saturn. Because of our observations they had planned to make observations to include the satellite. Not only did they get Epimetheus, they got a series of pictures showing the shadow of the ring going across. It was neat to experience a world going from a little point of light to actually seeing it as a chunk with craters.

There’s still discoveries being made like that, with Cassini and whatnot, but those first were always unique experiences. Dynamists knew that such a co-orbital situation was possible but it had never been observed before. The orbits were just slightly different, but they were different by less than their radius. What happens is, as they go around, they revolve in the plane of one other satellite. The satellites will come close, but they’ll have mutual gravitational attraction, and they’ll pull each other, and one will be pulled into a lower orbit and one will be pulled into a higher orbit, and then it’ll go apart again, and they play this dance all over again. It hasn’t been conclusively determined how it got in that situation in the first place.

Robert McMillan, on the founding of SPACEWATCH®

I think about the spring of 1980, Tom Gehrels had written a draft of a proposal to look for asteroids that might hit the Earth. He gave it to me just to criticize: “What do you think of this?”

I wrote back what I think looking back now was probably a pretty stinging criticism of it, because I thought the way that he was going to do it simply wouldn’t work. And I said so. I gave the reasons why, thinking, “Well, that’s the end of my job.” But I didn’t want to lead him on; I thought there were some real problems with the initial approach.

Instead of firing me he said, “Well, why don’t you help me do this project, because I think I need you.” So to my astonishment he made me the deputy investigator on SPACEWATCH® and we wrote a proposal. I think the first proposal was in March of 1980.

SPACEWATCH® is an exploration of the whole solar system for asteroids and comets, with an emphasis on potentially hazardous asteroids that might hit the Earth. In addition to finding a number of Potentially Hazardous Asteroids, PHAs, we’ve also discovered trans-Neptunian objects; we’ve discovered Centaurs that orbit in the outer solar system between the orbits of Jupiter and Neptune; and many comets. We’ve done scientific investigations of the statistics of asteroids in the main belt, and statistics of the asteroids in the near-Earth object region.

Over the last 26 years, SPACEWATCH® has gone through a number of revolutionary phases in which we’ve had different kinds of technology and equipment. We’ve upgraded the telescopes from time to time; we built a new telescope so we now have two. We’re observing very intensively on Kitt Peak with both telescopes as I speak. We’re well-funded by NASA at least until spring of ’09. Indications are we’re going to continue to have a role in follow-up and discovery of asteroids, especially the ones that are possibly going to hit the Earth.

I’m quite proud of the accomplishments of SPACEWATCH®. We have a certain niche in the world effort that nobody else is doing. It’s of course very hard work, observing on Kitt Peak, long hours, sixteen hour days, or nights if you like, and we all have to put in about eight nights a month, two telescopes with one person, so it’s a real handful. I’m one of the three observers. And I’m the Principal Investigator as of June of 1997, when Tom handed off the PI-ship to me. But he’s still associated with the project, he still goes to the telescope, and he offers advice and so on. His international reputation is still associated with SPACEWATCH®; we benefit from that too.

I see SPACEWATCH® as my life’s work in more than one way. I helped to invent it, and I’m doing a lot of observing with it, of course I’m responsible for it, getting the funding and so on. I am collaborating with people at JPL who are developing a couple of instruments, spacecraft, to detect asteroids from space. The reason that SPACEWATCH® is relevant to that is that ground-based telescopes will be needed to follow up on discoveries that are made from spacecraft, and so the ground-based follow-up is an integral part of these new spacecraft missions.

I’ve steered SPACEWATCH® in the last several years over toward following up objects after they get too faint for the survey telescopes to follow them. That’s our niche, doing faint follow-up, and that is ideally suited to collaborating with spacecraft missions. So I think I have a pretty decent future, a certain niche in planetary science. We have actually the largest telescope in the world that is dedicated full-time to searching for asteroids and following them up.

William Hubbard, on the discovery of Larissa

The planet Neptune has been one of my lucky planets. Neptune’s first satellite, Triton, was discovered in the nineteenth century, and after that there was a long period with no further discoveries of Neptune satellites. That was partly because astronomical instrumentation just had not progressed to the point that you could discover new satellites around this very distant planet. Kuiper—I think it was in the late forties—discovered the next satellite of Neptune, Nereid, which is, it turns out to be, a member of a class of very eccentric, small satellites that are orbiting Neptune. That was one of Kuiper’s discoveries, and it was a nice curiosity.

In 1981 we set up what you’d call a coincidence experiment in the Catalinas, trying to actually look for Neptune’s rings. I was the Principal Investigator on that project. We set up two coincidence experiments. One was on the Catalina 61-inch, which is now known as the Kuiper Telescope. The other experiment was on the 40-inch up on the summit of Mt. Lemmon. The idea was to monitor stars that were passing behind Neptune to see if we could detect rings. We saw a drop-out in our signal on both telescopes, and when we analyzed it, we concluded that we discovered the previously undetected satellite of Neptune. It’s now known as Larissa. I thought it was kind of neat that we discovered the next satellite after Kuiper’s satellite, using Kuiper’s telescopes. In fact, Kuiper is now buried at the telescope where we discovered this.

It’s kind of like deep sea fishing. You have this long line out into space and you don’t know what you’re going to reel in. We pulled in some other interesting things over the years.

Jay Holberg, on ground-based observing

We’re very fortunate here in Arizona because we have four or five observatories. You go up and get ready to make your observations, and you pray for good weather. A couple of nights of bad weather can set you back six months. If you come back and ask for more time, you’re with everybody else, so it’s a bit of a roll of the dice.

But people generally know what to ask for and how much to ask for, and you have a reasonable chance of getting what you want. You go up there and sit in the warm room and look at a monitor, and find your star and make your observations and move on to the next one. You’re up there all night taking data, and you come back down and tell a graduate student to reduce it, and hopefully you find what you’re looking for.

Peter Smith, on searching for extra-solar planets

Space projects in the eighties were rarer than in the late seventies. To keep myself busy, I helped a group looking for planets around other stars. We built an instrument that was accurate down to three meters per second, which is six miles an hour. Imagine looking at the surface of a star watching it pulsing at six miles an hour or higher.

This was before the new LPL addition. We built the instrument on the ground floor near the loading dock. We took a telescope out to the parking lot, and tried measuring the velocity of stars with a 14-inch Celestron telescope using a fiber optic to pipe the light into our laboratory.

Of course we couldn’t see anything but the bright stars. So we looked at Arcturus. I spent two years putting this instrument together and I was really hopeful that we were going to see a steady value, maybe one that bounced around at three meters per second. Instead, the first night we averaged our data, we got a hundred meters per second. The second, it was zero. The next day, it was a hundred again. Very disappointing.

It turns out that Arcturus is not a stable star: It has random pulsations. Nobody knew that; this was the most sensitive stellar instrument ever built. We finally figured out the instrument was okay, but it threw us off our schedule. We took the instrument up to Kitt Peak, where we had a dedicated telescope shared with Tom Gehrels who was looking for near-Earth asteroids. We got the bright time, he got the dark time: We were looking at bright stars, and he was looking at faint asteroids.

We had to spend two weeks a month up there, when the Moon was up. We’d alternate months between me and Bob McMillan. You’d be up there at the 36-inch telescope all alone, nobody but you in this big dome of a building. We only observed in the winter so night lasted 14-hours. You’d set everything up and start your observing. At about four in the morning, you’d battle to stay awake. Every hour we’d shift the telescope to a new star.

We had a TV screen that had an image of the entrance slit to the instrument, and there was a little blurry dot, which was the star. There was a circle drawn on the screen, and you had to keep the blurry dot in the circle. Then there was a counter that had numbers on it telling you how much light entered the instrument. It was like the dullest video game you could imagine. You tried to keep those numbers maximized by pushing the telescope drive buttons. After ten hours of that, your eyes were just dripping, because everything else was dark except for these little red lights. All the red lights would start to swim around.

So to keep from falling face-first onto the table and passing out because it was so dull and boring and you were so tired, you’d walk up to the top of telescope—this was a big dome, maybe five stories high. There’s a little place at the top where, if you climb a series of ladders, you can climb out under the sky. You felt like a sailor in a crow’s nest on top of a tall mast.

You had to be careful on those stairs. There’s no railing on one side and it’s thirty feet down. I remember one time walking up all those stairs, trying to stay awake, at probably four in the morning, and Halley’s comet was visible, rising in the East. I was hanging on, half-conscious because I was so tired, and I felt like was on a ship. I could feel myself moving. I think the wind was blowing. It was amazing because the stars were so bright and beautiful that I tried to reach up and grab one. That’s the joy of astronomy, I think. You see those stars and of course wonder about them and you’ve got your instrument down there and you try to see if there’s a planet on that particular one.

Unfortunately we weren’t too lucky with our choice of targets. There were maybe fifty stars available bright enough for us to measure, and we could only do twenty. You’ve only got 14 hours in the night so you can’t do too many. None of the twenty we choose actually had a planet. It turned out later that the first planets they discovered had a four-day period: A four-day year. We would’ve seen those right away, even at night; I think it would’ve gone right off the charts. If we’d just chosen the right stars, we would have discovered planets back in the mid-eighties. But we didn’t. Now it turns out that for about for every hundred stars, one has a planet.

Dolores Hill, on the K/T boundary

I helped out with K/T boundary samples. That was very, very exciting work, mostly by Alan Hildebrand. He was a very serious fellow who was quiet and kind. He would travel all around the world to all of the known K/T boundary sites, and bring back either chunks of rock out of a cliff, or material that he had removed from a cliff, in these little baggies. He would go to places that are very humid, so he’d have to leave the baggies open to let the moisture out. He would separate those out into different strata, and actually analyzed those samples. He developed a radiochemistry technique to analyze the siderophile elements, which are the metal-loving elements.

Even though in the popular press [Luis] Alvarez gets an awful lot of credit for identifying that there was high iridium in that layer, Alan—and also later David Kring joined him with Bill Boynton as his advisor—was actually the one to pull together information from a lot of different perspectives, and a lot of different data, to identify the actual site of the crater. I don’t think people really understand the whole story there, because, like I said, he was kind of a quiet person. He doesn’t look for credit, but he deserves it.

He analyzed all these materials, and the thing that confused people for so long was that the chemical signature indicated both an ocean impact and a terrestrial impact. It didn’t make any sense. One camp would say, “Well, obviously the big impact hit in the ocean, and we have no hope of finding a crater,” and the other said, “No, there’s terrestrial signature, it had to have been on land, it’s here somewhere.” It kind of bounced back and forth, and each ignored one side of the data.

He carefully looked at it all while this confusion was going on. He would attend conferences and a couple times people would come up and say, “I have these core samples that are kind of funny. We think we saw some interesting material there.” He’d take these core samples and put them out on the table, and he looked at those and realized that what was previously identified as volcanic soils was in fact impact.

Another person from an oil company contacted him one time and said, “There’s this funny circular depression. You might be interested in that.” That turned out to be the crater [the Chicxulub crater on the Yucatan Peninsula, Mexico]. It had hit half on the continental shelf and half in the ocean. Because of that, the material that was spread around the world had different signatures. So all these little bits of information he studied, magnetic anomalies, gravitational anomalies, just converged on this site. It was really fun, to see the whole process come together. His dissertation was exciting. It was just little bits of random information that came together.

Jay Melosh, on the SNC meteorites

When I came to the University of Arizona, a big problem had come up that I had been working on or considering. Round about that time, 1980, it was recognized that some very strange meteorites—the so-called SNC meteorites, shergottite, nakhlite, and chassigny—had come from a larger body. The proposal had been made that perhaps they came from Mars.

At that time, the best understanding of how impact craters worked said that there was no way to eject a rock at anything like Martian escape velocity and have it survive its flight. Gene Shoemaker said in no uncertain terms—I can still remember his voice echoing through the room—that it was absolutely impossible to get a rock off of Mars without it either melting or vaporizing. Yet these rocks had neither melted not vaporized, and it became more and more clear as 1980 turned to ’81, and ’81 to ’82, that they in fact really had come from Mars. ’83 was the clincher—dissolved atmospheric gases were found in one of the Martian meteorites that were an absolute dead-ringer for the Martian atmosphere. Basically all scientific resistance collapsed.

I was attracted to this problem where the best theory and the observations disagree, and started working on mechanisms by which the rocks could be ejected. In the end I recognized that it was the interaction of the shockwave in the rock with the surface of the planet that actually was responsible for ejecting the material into the upper atmosphere, a process I call spallation.

I worked on that pretty exclusively for the first couple of years I was here, 1982 to ’86 or so. I was working pretty hard on that mechanism by which rocks get ejected from their parent bodies. That’s now pretty much the accepted mechanism; we have a lot of direct observational evidence that that process is, in fact, what happens.

Dolores Hill, on meteorite research

The very first project was one where they had had some difficulties. It was to study compositions of individual chondrules and chondrule rims. We developed a technique that worked out very well I think. We would disaggregate or take apart meteorites and gently break the sample so that the chondrules would fall out, and then we tried to identify which ones might have a dark rim around it.

At that time it wasn’t known whether these were rims that had condensed onto the chondrule after it formed, or whether these just were particles that had been accreted onto the surface, or what. We wanted to find out. We would separate these chondrules and irradiate them. We’d send them to a nuclear reactor on campus at the University of Missouri, and when they came back, we would take the little chondrule and glue it to a push-pin, and grind it on a little piece of grinding paper. That would be our sample.

It was an ingenious technique—it wasn’t my idea—but the paper was not radioactive so it didn’t matter to us. We saw the sample that was deposited onto the paper. I would grind these little chondrules—they’re only about a millimeter, two millimeters across—on to a series of maybe four or five of these grinding papers, and then I would count those papers under gamma ray spectrometers. By looking at those we could tell what the outer layers of the chondrule were made out of. Then we popped the chondrules off of the push-pin and made little thin sections of them, and looked at them under an electron microscope.

At the same time, we were studying calcium-aluminumrich inclusions, otherwise known as CAIs. We made slices of this little thing on a special saw that we have, and then we broke off this rim area. We analyzed that through a radiochemistry technique that Bill Boynton developed to look for rare earth elements, a very critical group of elements. He pioneered that procedure.

We had a very famous person work with us as a post-doc, named David Wark. He’s since passed away. He actually studied the first rims on CAIs, and the rims are named after him: Wark-Lovering rims. He did several experiments that no one will ever repeat, because they were so difficult and tedious.

We were very privileged to work on the very first lunar meteorite that was discovered in Antarctica. It was called Allan Hills 81005. That was the first time we ever identified a lunar meteorite that had been ejected off of the Moon onto the Earth’s surface. We were able to do that because we had Apollo samples to compare it with. It was pretty exciting. We knew we should have these samples but we had never identified them. So that was a wonderful project, very exciting. 

That also then, I think, laid the groundwork for, again, being privileged to study another meteorite called Calcalong Creek, which is a lunar meteorite in Australia. That one was really famous for a long time because it was, at the time it was discovered, the only meteorite not found in Antarctica from the Moon. There’s no good reason why they’re only found in Antarctica, so it was exciting to finally spread out. Since then many more have been discovered in the Sahara Desert. There should be more in other places, we just haven’t found them. We’ve worked on Martian meteorites as well.

Jay Melosh, on the origin of the Moon

While I was here, the idea that the Moon had been born of a giant impact came up. It was suggested in a meeting around ’84, and soon there was serious talk about how the Moon was made. I got involved with that, actually in collaboration with Chuck Sonett. I didn’t go to the actual meeting. I had some responsibility to give a lecture at the Flandreau Planetarium on Martian meteorites, so I couldn’t go to the meeting on the origin of the Moon which took place in Hawaii. But a number of people came through here on the way back from that meeting, and I heard about the speculations.

I decided right then and there that all the speculations were flat wrong. The proposals that had been made were transparently incorrect. I figured I could spend a weekend and write up a paper to get rid of all this nonsense.

In the process of that weekend working—it actually took place mostly on an airplane, I was going to another meeting—I realized that there was a way out. What people were talking about was patently not going to work, because the people who were talking about this didn’t understand impacts very well, but there was a way in which impacts could launch enough material to form the Moon. Furthermore, in the process of launching it you would have to vaporize most of the material, and if you condense that material in a vacuum it would have the chemical signature that accounts for the difference between the Moon and the Earth.

I ended up writing a paper. Chuck Sonett was the co-author. We wrote up this paper in which we actually agreed with the impact origin, and described in detail how it could happen, and the chemistry. That was published in the book that contained the proceedings for the conference, even though I didn’t go to the conference.

Steve Larson, on comets Bennett and Halley

Laurel Wilkening came in with Mike Drake, at the same time, not long after grad school. She went on to become quite an administrator. She was on the International Halley Watch oversight committee. She knew that I was interested in comets, and she encouraged me to propose to participate.

One of my problems, if you will, is that I never got a PhD. I started taking classes in the department, and after taking six units a semester while still working full-time, I didn’t get great grades and I was basically told I didn’t have a future in planetary astronomy.

But I was carrying out this cometary physical characterization program, and so I took her advice and I sent in a proposal. I had done work also on comet Bennett. It showed some fantastic structure at the head of the comet, which I had seen in drawings before. I thought they were figments of someone’s imagination. There were spirals and all kinds of fantastic features, and the comets I had seen up to that point were just fuzzy things. But comet Bennett came along, and by God, there were these spirals. That just absolutely blew me away, and I said, “I’ve got to learn more about these.”

We had a conference on comets, and published a paper on the determining the rotation of the nucleus. It’s like a lawn sprinkler effect; you’re putting stuff out, but because you’re rotating it, it looks like a spiral. I thought that was pretty cool. I had been looking out for other comets that had those kinds of features, so I proposed to be involved in the so-called Near Nuclear Studies Network, which was one of the many subdivisions of the International Halley Watch that specialized in different techniques.

I won an award to be part of that. I was a deputy discipline specialist, is what they called it. That turned out to be another fantastic experience, because I met people from all over the world, did a lot of traveling, and set up this network where we were observing the comet constantly at different longitudes.

Because the work on modeling these jet features on Bennett, I was invited to be a guest investigator on the Soviet Vega spacecraft mission to comet Halley. That made me a member of the Inter-Agency Consultative Group which had been set up to coordinate all the investigations. Those were interesting times, as well. I’ll never forget going down to South Africa. I was able to obtain my very own CCD camera for the first time, to make observations of comet Halley. We had built it so it was portable, so we shipped it down to South Africa, because the comet was more visible down there, and at its brightest during the time of the spacecraft encounters.

I went down with a guy I had hired to actually do the observations, to set things up and start observing, but I had to fly to Moscow for the encounter. I had just sent a telegram to the guy saying, “I’ll be up there at such-and-such a time,” but I never got anything back. I had no idea where to go, who to contact. But they had arranged to have somebody meet me, so it was okay. I went back to Mission Control and observed the data coming back from that encounter, and then that was followed a few days later by going to Darmstadt in Germany where the European Giotto spacecraft flew by.

Lyle Broadfoot, on airglow experiments

About 1986 my group started to get involved with the U.S. Air Force. That’s when we started to build experiments for the shuttle. We did ground-based experiments as well at the AMOS [Air Force Maui Optical Station].

We didn’t do much ground-based other than this work we did with the Air Force. But it was still flight data—flight-based—because what we were doing was observing the shuttle as it flew over the optical station. With their instrumentation—and we had our instrumentation tied to theirs—we would observe the airglow emissions.

Airglow means that something is active in the atmosphere, like the aurora. The aurora occurs because electrons, protons, are trapped in the magnetic field, and they come into the atmosphere and they excite the upper atmosphere. The emission changes as a function of altitude, and by observing the optical emissions we can say something about the density of the atmosphere at that moment.

What we were doing with the shuttle was they were firing their thrusters, and they were turning their thrusters to the ram direction to point their thrusters forward and fire them, and we were observing them to see what the interaction of the thrusters with the atmosphere was. So this is airglow. We had the shuttle do different configurations and fire jets in different directions, and we looked to see if we could see a signature that would be useful.

Of course, this was all before the Berlin Wall came down. Once the Cold War was over, that program started to slow down. At that time what we were trying to do is get signatures that would allow us to identify types of rockets and stuff that might fly over from some unknown location in the Soviet Union. So that work kind of slowed down. But we continued to do airglow.

The advantage to us working with them was that the experiments we did working for the Air Force only took two or three days—or probably just one day, because there’s not too much going on. The rest of the time—because we were usually up for seven to ten days—we used our instruments to look at different airglows in different directions; watch the airglow as the sun sets, and see what we could see in the night sky, and that type of thing. We worked on trying to tie that in to atmospheric models, trying to figure out how different things move around in the atmosphere.

Paul Geissler, on the founding of PIRL

Image processing was really just getting started. It was very awkward, very hard to do, so it was a good time to get into it. They had hired a new professor named Bob Singer, and I wrote to him even before he showed up and said that I wanted to work with him. I basically pounced on him before he even unpacked, and he agreed to take me on as a graduate student.

His idea was to start a Planetary Image Research Laboratory [PIRL], which still exists. It’s the one that Alfred [McEwen] is head of now. Bob started it. Brad Castalia was one of the first principal programmers there.

Basically it started off with eight single Sun workstations and nine-track tape drives because that’s where we got images from. We would get images and download them on the tape and basically write software to be able to process them.

Our recording medium was a camera and a tripod that took a photograph of the screen to make a slide; it was very basic. We had a gorgeous monitor—it cost twenty thousand dollars in the late 1980s. It had 1024 by 1024 pixel resolution: Unheard-of.

We picked up equipment as we went. We eventually got a digital film recorder. We got a lot more workstations since they got cheaper as more graduates started working on images. But for a while it was really just a handful of us that were trying to process images. Normally what would happen is people would get hardcopy, photographic hardcopy, and they would slice it up and paste it together.

The things that we did were actually pretty impressive, because we didn’t really have any software that we could run. We made a decision to go with UNIX, and the best image processing software at the time was run on a VAX. They had one in the CCIT, in the University computer cluster. What we would do is we would read our images off of a tape, and then we would send them over to CCIT, do the preliminary processing on the VAX, and then send them back, and import them into the software package we were using, which we were busy writing at the time because it didn’t really have much functionality.

Now I’m happy to use other tools to do it, but I’m not afraid to hack and get it to do what I want. But more importantly I know what it should do. Image processing is wonderful because in any other kind of numerical work, if you make a mistake you could be off by a factor of ten to the sixth and you may never know, but in image processing you just look at the screen and you can tell, “Oops.” It’s pretty easy.

Larry Lebofsky, on Project ARTIST

The high moments were the heyday of what was called Project ARTIST, Astronomy Related Teacher In-Service Training. We got a very large grant from National Science Foundation for working with teachers to teach other teachers. That, to me, is probably the highlight of what I’ve done over the years. I did that for five years; a very successful program. People are still using some of our materials.

Part of me says: Well, I’m at the college level; what I should be doing is at the college level. But the other part of me says: You’re not going to get good students unless you provide better training for the kids at a younger level.

At the college level, you’re not going to get better future students unless you better prepare the future teachers. So when I’m looking in my classes I always grab a hold, so to speak, of my future teachers.

Training the future teachers, giving them the background they need at the college level so they can teach future students at the University and better educate the public is, I think, an important thing to do.

Harold Larson, on the development of the Teaching Teams program

At that time the University was being more insistent that we get more involved in undergraduate education. This is when the student-centered research university was slowly becoming the mantra. It meant basically that this Department had to do more teaching.

Gene Levy hauled me into his office and said, “You’re going to teach.” So I was literally thrown into a classroom with no help. We taught just one section of an undergraduate course, so that semester I was the one teaching it. There were 90 kids in the class. That was big back then. It was in a building that was subsequently torn down, mercifully. It had virtually no AV capability, it had an overhead projector and the plug kept falling out of the wall because the outlet was so worn. It was a horrible teaching environment. They put so many kids in the classroom I had hardly any room at the front to walk back and forth without tripping over feet.

I got through it. But I vowed at the end of the semester that I was never going to teach a class that way again, just lecturing with virtually no way to enhance the learning environment. So the first thing I did was choose carefully the next room I taught in. We didn’t have our building, so there were other classrooms on campus that would have more amenities. But the other thing that I wanted to do was get the kids involved to help me do things, like being assistants for some hands-on project, just to make the classroom environment more interesting.

That eventually led to the Teaching Teams program, which formalized this arrangement, because it turned out that other faculty on campus were doing the same things. None of us knew the others existed. In ’96 or ’97, the Learning Center who knew about these little pockets of learner-centered education called us up, arranged a meeting with us and we all started comparing notes and said, “Wouldn’t it be a good idea if we got together and came up with a University-wide program? Let’s write a grant to the government.”

So we did and got the grant the first time through, and that’s how the Teaching Teams program formally started. There was a lot of excitement back then about the new gen-ed program, a student-centered research university, not just lecturing but getting students involved, trying to bring innovation into the classroom. So we rode on that wave.

The program has grown, and has achieved significant successes in how it’s been able to transform classrooms both by using students who are willing to volunteer and faculty who are willing to change their teaching styles. We’ve now been doing this for almost ten years, we’ve had multiple grants from the U.S. Department of Education, Hewlett Foundation, Kellogg Foundation—we’ve never been turned down for a grant, which is really exceptional in this very competitive field, because we’re always talking about doing something that addresses national programs, and we’re doing it in a classroom. We’re doing it in classrooms that no one else dares touch, the high-enrollment gen-ed classrooms.

Steve Larson, on the formation of the Catalina Sky Survey

In the early nineties, I got a call from a student over at Steward [Timothy Spahr], who contacted Ray White and told him he was interested in comets. Ray said, “Well, you’d better contact Steve Larson over at LPL.” So he did, and he was willing to work for free just to get involved. I took him on. He wanted to discover a comet.

The Schmidt Telescope that Kuiper built for Pat Roemer hardly ever got used. I showed him how to use it and how to develop films and all that. He ended up searching the sky for comets, and he found a couple. He also found a couple Earth-approaching asteroids.

This was just after the extension of the Halley Watch when Shoemaker-Levy 9 impacted Jupiter. Because I had so many contacts I was able to put together a network of people to observe that from the ground for the five-day duration of all those impacts. That was a whole other little project. We got very successful observations from the four major telescopes.

During that time I was attending the Lunar and Planetary Science conference in Houston every year, which is more for geologists, and that’s when I hooked up with Gene Shoemaker. Of course, he had a program for discovering comets, and much of my comet characterization was observing those comets, and in some cases observing near-Earth asteroids that turned out to be comets. I got to know him, and he was the one who really got me believing in near-Earth objects as being an interesting subject. Of course the discovery of the Chicxulub crater up in Yucatan kind of cemented the concept.

Tim and I started working on adapting that to the Schmidt Telescope up here that hadn’t been used in years. For the Shoemaker-Levy 9 impact we were able to get a second CCD to replace the original Halley Watch CCD, which was a bigger and better one. But they had a sale at the end of the year and I got it cheap, so I had money left over, and that allowed me to get a bigger chip for the Schmidt. While Tim was gone at school I converted this photographic telescope to a computer-controlled detector that had a very precise field.

When Tim graduated, he got offered a post-doc here. He started experimenting with being able to look for NEOs. We succeeded in that, but we didn’t have any money. We were actually building our own computers from scratch, because you couldn’t buy a computer with the capacity. It was a very shoestring effort.

Tim and Carl Hergenrother, who came from that time—those two, me and another student, we formed Catalina Sky Survey. I worked for a couple years building up software and going to find things, and we planned to do some upgrades, and I was able to get some money from NASA to upgrade just at the time that things were starting to fail: Computer was not working, network was crashing.

Tim always wanted to work at the Minor Planet Center, which is where we submit all of our observations. We had this meeting on NEOs in Torino, Italy, where this Torino Scale was being done, and the Director at the time, Brian Marsden, said, “I really want to have Tim. Would you mind if I hired him?” I said no. I knew Tim’s life goal was to work there.

He’s now the Director of the Minor Planet Center. I’ve had great relations with them since he’s been there. It’s been kind of rocky, because again, they had growing pains, as surveys got better and better. We send in ten thousand observations a night now. So they had to handle a lot of observational stuff.

But anyway, he had the opportunity to leave. Everything was crashing around us, so I decided to take the telescope down, and start the modifications and have some new optics made. Unfortunately we were out of commission for three years. But in that time we were completely rebuilding and refurbishing cutting-edge instrumentation, for the Schmidt, for the one-and-a-half meter on Mt. Lemmon, and for the Schmidt Telescope at Siding Spring, Australia, which even today is the only place in the Southern hemisphere looking for NEOs.

Comet McNaught, the most spectacular comet in our lifetime, was discovered in our survey data. We turned out to be out of commission for a while, we did a lot of upgrades, and when we came back on in 2004, we quickly became a leader and we’ve been a leader ever since. Right now about two out of every three NEOs we discovered.