My Life In Comets

First of all, unprofessional as it may seem, I have to say that I am incredibly honored to do something even remotely connected to Dr. Phil Plait, as I've been a tremendous fan of his work on the Bad Astronomy website since Middle School. I really did learn an incredible amount from the site, and I've tried to do my part in his noble effort to clear up common misconceptions about astronomy when I hear them from friends or colleagues. (NO SOUND IN VACUUM, DARN IT!) My cousin Alexa didn't quite understand why I got so excited over seeing that she had the website's companion book as a textbook for her college astronomy class a few years ago--I'd never seen a print copy before! (She sent it to me as a gift after that semester was over.)

I don't know what it is, but being at college this past year and a half has really made me think about my younger days and what's changed and what hasn't. Today, during my Astronomy 101 final exam, I calculated the radius of a hypothetical extra-solar planet's orbit using Kepler's Third Law. But it doesn't seem like that long ago that I was an eight-year-old sitting at a table in my elementary school library reading easy-to-read books about Comet Halley.

Most of those books, from what I remember, had been written shortly before that comet's 1985-86 appearance, and while I was old enough to know that was in the past and that I had missed the chance to see it, I wasn't quite sure by how much I'd missed it. (As I mentioned back in January, I was -7 years old at the time.) So, I knew that the space probes the book said were going to visit Comet Halley had already done so, and I'd missed the chance to follow their missions, which was kind of a bummer, because the book made them all sound really cool.

I was around in 1996 and 1997, when Comet Hyakutake and Comet Hale-Bopp were visible from Earth, and my father tells me he took me out to see one of them over our house, he isn't sure which. Having been either three or four at the time, though, I don't remember any of it, and when I look at the pictures that astronomers, both amateur and professional, took of those comets, I mentally kick myself a little over that.

But, at that very same age, seven or eight, sometime in 1999 or 2000, I stumbled upon a magazine article (I want to say it was in US Kids) very similar to that old book about Comet Halley, talking about the Stardust spacecraft which was either about to be or had just been launched on a journey to Comet Wild 2, and encouraging students to follow along. It sounded interesting, all right, but given my age, the 2004 encounter date seemed impossibly far away and I forgot about the article in the intervening years. I think I did see something on the news about it once Stardust actually arrived at the comet, and I definitely remember hearing about the recovery of the capsule containing the samples of cometary material it had captured, two years later, in 2006.

I didn't realize until later how remarkable it really was that this probe had sent back samples--pieces of the comet itself!--to Earth from a world farther away than the moon for scientific study. While I understood that intellectually long before, the full emotional impact of those facts didn't hit me until last year, when I actually saw the sample return capsule myself at the Air and Space Museum in Washington. It's in the Milestones of Flight gallery, under the Spirit of St. Louis and across from the Apollo 11 Command Module, because it is a milestone--the first spacecraft to return samples from beyond the moon.

There are a few other uncrewed satellites or robotic probes in that gallery, but they're all replicas or test hardware--the real ones burned up on reentry or are still out there in space. The Viking Lander next to the Stardust display is just a spare used for testing on Earth, because the real ones are still on Mars. The Air and Space Museum officially owns the real ones, because NASA transferred ownership to them, but they're still on the surface of Mars and not in the museum, because they were never made to return to Earth.

But that capsule is real. It left the Earth, and it traveled through space, and it visited another world and collected little pieces of it, and it came back and human hands touched it again.

And I think that's incredible.

I was watching closely last year when Stardust completed its final mission, flying by Comet Tempel 1 on Valentine's Day to examine the mark left by the 2005 Deep Impact collision Dr. Plait talked about in his video. A small crater was still visible.

In his book Star Trails, David Levy (of Shoemaker-Levy 9 fame) mentions how a Deep Impact mission scientist described that collision--"It's [the] revenge of the dinosaurs!"--Earth-life reaching out to strike back at a comet and slightly change its orbit. Like Dr. Plait said, that's a capability we have that the dinosaurs didn't. We sent a spacecraft to meet Tempel 1 and altered its surface topography, and then, six years later, sent another spacecraft to meet up with it and photograph the results--one that had already done everything I mentioned above.

Am I bummed that I didn't see Comet Halley and that I don't remember Hale-Bopp and Hyakutake and that I didn't follow Stardust and Deep Impact more closely? A little bit, but I can't change the past. I'm lucky to live at a time when my species is doing such incredible things, and there are surely plenty of historic moments still to come. And I'm hopeful about Comet ISON next November...