I Dreamed of Riding the Rocket into the Sky
As told by Michael E. Brown
If you grew up in Huntsville, Alabama, in the late 1960s and early 1970s, one of the things you got used to was having the entire ground shake. I’ve gotten used to it again, living now in California, where the occasional earthquake will knock you off your feet or your glasses off the shelves. But in Huntsville the culprit was the Saturn V rocket, which, when ignited at the test stand 15 miles out of town, caused everyone to stop, look west, and wait for the smoke to roll into the sky. When I felt the tests rattle and the smoke rise I would dream of riding the rocket into the sky. It seemed plausible. Astronauts lived down the street; rocket engineers lived all around; the world was clearly heading into space, and I was determined to be there.
It didn’t work out, of course. The Saturn Vs shut down, Space Shuttles exploded, and I left for college at Princeton fascinated by space, but not believing that it was a viable future. I was going to do something practical. I was going to be a physicist. But in my final year in college that one of my professors casually remarked: “Why not go be an astronomer? We need more people out observing things.” Throughout the years of my interest in astronomy, I had never owned a telescope. I had never visited an observatory, but with just that tiny prod I found myself just a year later at the Lick Observatory outside of San Jose, California, trying to figure out all of the things I probably should have already known before beginning graduate school in astronomy at Berkeley a few months earlier.
Determined to study distant galaxies
At Berkeley, I was determined to study the most distant galaxies in the universe, and quickly began working with Hy Spinrad, one of the leading astronomers in that area. But Spinrad also had a side interest in studying the compositions of comets. Unfortunately, none of Spinrad’s students ever really had much of an interest in comets. In astronomy – at least in the 1990s – the solar system was the back water of astronomy. Real astronomers studied things that were distant and faint, not the bright planets that were just next door. Besides, planetary scientists had probes flying past the outer planets, and orbiters around Mars and Venus. Why bother using a telescope? Nonetheless, Spinrad persisted, and to make sure his comets got a little attention he always forced his students to spend one summer studying comets before being allowed to move on to the more interesting galaxies on the edge of the known universe.
I was as uninterested in these nearby things called comets as anyone else until one night when I was up at the Lick Observatory collecting the spectrum of a bright new comet and I stepped out into the dome to look right where the telescope itself was looking, and there, right down the barrel, was the faint smudge that was the comet whose light we were slowing gathering into our spectrograph. You could never go that with a galaxy at the edge of the universe; distant galaxies are just coordinates on an abstract sky. But the comet was there; it was real. And you could watch it, night after night, moving across the sky. I was hooked. The solar system, rather than seeming like a back water, seemed like the only place in the sky that was real.
Near the end of my graduate career, after years of studying comets and Mercury and the Moon, and other familiar sights in the real sky, a relatively new postdoctoral scholar in the department – Jane Luu – told me about a strange object that she had just discovered outside the orbit of Neptune in what she called the “Kuiper belt.” Kuiper belt? I’d never heard of it. I went back to writing the last few chapters of my thesis on volcanoes on Jupiter’s moon Io. Fewer than 5 years later, though, as a young professor at Caltech in Pasadena, California, I realized that the Kuiper belt was exactly what I should be looking for. By then, Jane and Dave Jewitt had found enough objects to make it clear that this region was going to be home to countless objects. Crucially, however, the current technology made it significantly easier to search for the much more common small faint members of the region than the rare large bright members. Yet the largest bodies were the ones from which we were most likely to discern clues to the history and nature of these bodies on the edge of the solar system.
"Kuiper belt? I’d never heard of it."
I was eager to find these largest brightest bodies, but because the current technology of extremely sensitive but extremely small digital cameras wouldn’t allow me to cover enough sky to have a hope of finding anything interesting, I reverted to the comparatively ancient technology of not-very sensitive but extremely large photographic plates. Using these photographic plates, we spent almost every night in the fall of 1997 and 1998 searching for the brightest objects at the edge of the solar system. In 1999, while tracking down every potential object that had been discovered, I made an astounding discovery: I had just spent three years finding absolutely nothing.
"I made an astounding discovery: I had just spent three years finding absolutely nothing."
Large-scale digital cameras
Rather than being discouraged, however, these three years cemented my desire to find these brightest objects, so when, a few years later, the chance came to work with one of the first truly large-scale digital cameras, I jumped. The camera was, in many ways, an improvisation. It used large numbers of cast-away detectors to assemble itself into what was, for most of a decade, the largest – and possibly most difficult to work with – digital camera in the world. But this quick start paid off. By using the telescope nearly every single night for eight years, we covered nearly the entire sky and found nearly every bright object in the Kuiper belt there was to find.
While the public was fascinated with each increasingly larger discover (Half the size of Pluto! Two-thirds the size of Pluto! Bigger than Pluto!) the real scientific excitement came because, as we anticipated, every single object was bright enough that, with detailed follow up from all of the biggest telescopes on (and off) the earth, we could slowly start to put together the stories that these objects were telling us. We learned about giant impacts in the early history of the solar system, about atmospheres slowly drying up on these distant cold objects, about the assembly of bodies in the solar system, and about the conditions at the time of the birth of the sun itself. Being the first person to ever get to see these largest objects discovered over the past century was always intensely exciting, but, to me, the true excitement and reward of these discoveries came not from simply being the first to see them, but from having the opportunity to be the first to try to explain them and tell their stories. Each of the largest objects was sufficiently different that with every discovery we learned something totally unanticipated about the solar system.
"The true excitement of these discoveries came from having the opportunity to be the first to try to tell their stories."
A story no one knew was there to tell
I’ve never seen these objects at the edge of the solar system; they are, in some ways, as abstract as the most distant galaxies in the universe. And yet I can still strongly feel these objects as an intimate part of our neighborhood; I can now see that this exploration is a natural part of the reaching into space that I so wanted as a child. My own daughter Lilah is growing up in a world where so much more is known than I could have guessed back in Alabama in the 1970s, but I hope that she, too, will have the chance to see places and things and perhaps worlds that no one has ever seen before, and that, when she does, she will have a chance to tell a story that no one even knew was there to tell.