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The Evolution of LPL: 1973-2000



Ground-Based Research
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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.