Kavli Meets Kuiper

Two decades later, three scientists are rewarded for discovering a new body of objects in our solar system.

(Courtesy Jane Luu)

Nearly 20 years ago, a Massachusetts Institute of Technology professor and his graduate student embarked on a project to find new objects in the outer solar system, motivated by the call to arms behind so many scientific discoveries: "If we don't do it, who will?"

Each year, the Kavli Foundation gives awards to scientists making "fundamental contributions" in their field of study. In 2012, David Jewitt, the former MIT professor now at the University of California, his former student Jane Luu, and Michael Brown of the California Institute of Technology were jointly awarded the $1 million Kavli Prize in astrophysics "for discovering and characterizing the Kuiper Belt and its largest members, work that led to a major advance in the understanding of the history of our planetary system."

 Air & Space spoke with Luu, who has moved on from the world of observational astronomy and now works on laser radar systems at MIT's Lincoln Laboratory. She told us about studying the Kuiper Belt, what it means for demoted planet Pluto, and what we still hope to learn.

A&S: Were you surprised to win the Kavli Prize?

Luu: Oh, absolutely. I did this research 20 years ago. So yeah, I'm extremely surprised. I just assumed that everybody forgot about it, and that was that.

Why did you and David Jewitt start looking for the Kuiper Belt, and how did you go about it?

I had just come to MIT as a graduate student and was looking for a project to work on, and he said, "Why don't we look for things in the outer solar system, beyond Neptune?" His idea was that the only object known at that time beyond Neptune was Pluto. He thought that was kind of odd, because there were so many things inside Neptune's orbit, and there was nothing else outside. According to the model of how we believe the solar system originated, it formed from a disk of dust and gas. That disk didn’t have any sharp cut-off around Neptune's orbit. So why is there such a sharp drop-off in the population of the solar system? He said, "Well, maybe it's really empty, maybe something happened and things that used to be out there got sucked away somehow. Or maybe things just seem empty because nobody looked."

The way to answer that question is to do a survey. We can do this with a CCD [charge-coupled device], but a CCD at that time didn't have many pixels; the CCD you have in your camera now has many more pixels than on the ones we used back then. The biggest CCD we had access to was 500 pixels by 500 pixels, so the field of view was very small. To use such a tiny little camera to survey a big part of the sky seemed like a pretty daunting prospect. Up until then, all the surveys of the solar system were done with photographic plates, and those have huge views, several degrees on a side, and that's how people covered big areas of the sky. I remember asking Dave, "Isn't it kind of crazy to do a survey with a CCD?," because nobody had ever done this before. And he said, "Yeah, but if we don't do it, who will?" So that was the beginning.

How long did you think it would take?

We were realistic. We didn't think this could be done in six months. We had a very small field of view, so we knew it would take us a while to cover any area of significance. It wasn't my Ph.D. thesis, because the prospect of finding nothing was very, very real. 

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