Telescopes & Research

George Coyne, on the need for ground-based support

Space exploration began to boom, because of money from NASA and all, but it did not detract from ground-based research. They went together. We realized very early in the beginning that we’d need large telescopes on the surface of the Earth as well as telescopes in space, experiments in space. You can’t put all your eggs in one basket. They go together.

The reason they go together is a very simple and technical one. The Earth’s atmosphere does two things that astronomers don’t like about it. One is it disturbs the light. If you look over a hot road on a summer’s day, you’re driving down and you see a shimmering light, it’s because the road is causing the light beams to [shimmer]. The Earth’s atmosphere does the same thing.

The second thing it does is it acts as a filter. There’s some ultraviolet radiation—thank God for us—and some radio waves that never get through the atmosphere. The conclusion from that, those two things, is that there are some things you have to do in space, because you’d never get the information here. The Earth’s atmosphere filters it out. But there are many things that you can do on the Earth’s surface without going to the expense of getting outside the atmosphere so that you can get away from this dancing light.

What has developed over the years is what we call adaptive optics, which is the way that a ground-based telescope, by certain techniques, can sense the perturbations of the Earth’s atmosphere, send them to a computer; a computer can tell the telescope mirrors, the secondary and the primary, what to do and where to correct for these perturbations.

At times, to 98 percent or so, a telescope on the surface of the Earth can act just as well as a telescope in space; and it costs, at least in those days, 500 times more to work in space than it does on the ground. You don’t spend that extra money if you don’t have to, if you have these special techniques. The excitement of the early years was that space was going to become more and more an important component, but we realized right at the beginning that it had to be linked to very high-quality large telescopes.

William Hartmann, on photographic lunar research

T6, being a long thin building, had the tunnel in where we projected photographs of the Moon onto a globe—onto actually a half-globe, a three-foot, white half-globe—and then re-photographed that globe from different directions so that we could see the structures on the Moon as they would look from overhead.

When we projected images on that globe, we could walk around to the side and see these structures in ways that people had really never seen before. We discovered that, particularly, there was a big, beautiful bulls-eye structure, multi-ring basin that turned out to be an impact structure—huge, a thousand kilometers across, on the east limb of the Moon. It’s called the Orientale Basin. Looking at that made it obvious that a lot of the other basins, like the Imbrium basin and Nectaris and so forth, were the same class of multi-ring bulls-eye structures. We could trace these rings.

Kuiper and I published a paper on that. That paper was immediately picked up by the group of Flagstaff, and they were really receptive to what we were doing. They were doing mapping of the Moon, too. The umbrella situation was, “We need good maps of the Moon; we’re going to send people to the Moon,” as President Kennedy set as the goal for the nation. We were all involved in that.

I was very proud and happy about this first paper. I went to Kuiper’s office—this would have been winter of ’61, ’62—and I said, “Look at these pictures, we’re seeing these multi-ring structures. There’s clearly some kind of radial and concentric symmetry.” It hadn’t been fully recognized before, because the best example, Orientale, was way around on the moon’s edge, and the other examples were either beat up by subsequent impacts, or mostly flooded with lavas. The pattern is kind of like a bullet going through glass, the way it shatters, and the crust of the planet was shattering in that kind of spiderwebby-looking thing, with emphasis on these big rings.

He agreed to publish a joint paper in the LPL Communications series, which he had started. That was my first published article. I think he let me be first author on that. I always thought that was unlike some big department heads that you still hear about in other universities now who demand to be an author on either everything that’s published, or sometimes even first author, because these other people are junior people. Kuiper immediately and graciously let me, an unknown graduate student, be the first author on this discovery paper.