Q&A With Malcolm Hartley, Discoverer of Comet Hartley 2
Malcolm Hartley discovered Comet Hartley 2 back in 1986. On Nov. 4, NASA's Deep Impact spacecraft will make a close flyby of the comet, coming within a mere 435 miles (700 kilometers).
Credit: NASA/JPL-Caltech, courtesy of Jonathan Pogson

On Nov. 4, NASA's Deep Impact spacecraft will make an up-close visit to the small Comet Hartley 2, marking just the fifth time ever that a comet has been imaged from nearby.

It will be the second iceball encounter for Deep Impact, which served as mothership for a 2005 NASA mission that crashed a probe into Comet Tempel-1.

Comet Hartley 2 was discovered in 1986 by astronomer Malcolm Hartley, who spotted it while poring over photographic plates taken with the U.K. Schmidt Telescope at Siding Spring Observatory, near the town of Coonabarabran in New South Wales, Australia. [Photo of Comet Hartley 2.]

While Hartley primarily studies galaxies and other phenomena beyond our solar system, he discovered about 10 other comets — he has said he doesn't keep a faithful log — in a similar fashion.

NASA invited Hartley to partake in its flyby festivities at the agency's Jet Propulsion Lab (JPL) in Pasadena, Calif. SPACE.com caught up with Hartley to talk about comets, the thrill of discovery and what it's like to be the most famous person in Coonabarabran (population 2,600).

Where are you going to watch the flyby?

I'll be at JPL, in Mission Control. NASA has brought me here, so I'm kind of at their disposal. It's wonderful to be here, and it's a great thrill for me and my wife.

I never really expected anything like this. Obviously, 24 years ago, when it was discovered, you're elated for a short period of time, and then you forget all about it, which I had done until the middle of this year, when somebody at JPL contacted me and said, "We're interested in having you over here." I was overjoyed to hear that. And we've gone from there.

Are you excited to get a better look at this comet than you were able to get back in 1986, when it was just a streak in the sky?

That's right — it was just a very faint streak. The discovery image was hardly there at all. I'm very, very excited about getting so close to it, and hopefully being able to see surface features on the comet. I hope that we're going to get a lot of science out of it. It's extremely interesting. [Best comet images of all time.]

You study galaxies, but do you still have a soft spot in your heart for comets? It must be nice to get your name on a few of them.

Oh, yes, of course. I do still have a soft spot for comets. It's really thrilling to discover one and to think that you've made that discovery. Every scientist wants to make a discovery. And so to find something that gets your name attached to it and will be there long after you've disappeared — that's great for you and your children, and your grandchildren and the people that follow.

What are the odds that there's going to be a close flyby of one of the other comets that's got your name on it?

Well, the odds are very remote, I would think. I'm happy they're going to one.

My granddaughter wanted to go on the spacecraft as well. She's only three years old, and she was very keen to fly to the comet. When she found out that we were coming here [to the U.S.], she was desperate to go with me. She thinks I'm flying to the comet. I explained that I wasn't actually going to the comet, but she said, "Oh, we must fly — we must all fly to the comet."

She's only three. Perhaps when she's 33 — who knows where she'll fly? [Top 10 Private Spaceships Becoming Reality.]

Any predictions about what the flyby is going to show us?

Predictions are hard. Anything we get, any detection — both spectroscopically and visually — will be very interesting in comparison with the other four comets that have been visited by spacecraft so far. It will be really interesting to compare this with the Tempel-1 imaging, and I just hope there are some features there that are a revelation in some way.

It's such a small comet, compared to the others that have been visited. But its behavior — its outgassing is stronger than all the others, and that is certainly very interesting.

Is the main point of the flyby to keep building up our sample of comets, so we can get a better general sense of what makes space rocks tick? Or is there something we can learn from this one in particular?

Well, I think, given its size, there will be some interesting things we can learn from this one in particular. But building up a general sense is extremely important. And the more comets that we visit, the more we'll begin to understand how they tick. And that would give us a lot of information about the evolution of our solar system. [Gallery: Solar System Remade.]

I'm not a solar system astronomer — I'm more galactic, extra-galactic. But it's still really exciting, and it's interesting to speculate and to revise and to learn more. And it captures the public imagination. The things NASA is doing are just mind-blowing, really. They can fly billions of miles and get within 700 kilometers of this object, which is stupendous.

How did you discover the comet? You saw it on a photographic plate, right?

Yes, as part of the quality control of the survey that we were undertaking at the time. The telltale thing about a comet is that it's a trailed image, and it usually has a kind of halo around it. This one was quite faint.

Really, the way that we found comets on the U.K. Schmidt survey plates is kind of by accident. We were looking for interesting things on the plates. And one part of my job was to do that. So if there is a comet or a fast-moving asteroid or something like that on the plate, you'd take special note of it.

And then of course, you're interested to find out if it's a known object, or whether it's an unknown object. And if it's an unknown, then it gets your name on it.

The way we heard about it was a telegram. Now it's an email, but it used to be a telegram. It was sent out to say that such-and-such comet has been discovered.

A telegram? It seems crazy that that was the technology used to alert people back then. It wasn't that long ago.

Yes, telegrams in those days. A little piece of paper.

When are you going back to Australia? When does this tour end for you?

We fly out on Nov. 5, the day after the flyby. It'll all be over but the singing and dancing by then, I think.

It's just great for me to be a part of all this. I'm just lucky that NASA chose to fly past a comet with my name on it. It could have actually been one of two or three hundred comets that they visited, but I'm just the lucky person whose name was on the one they picked.

Do you reckon all of this to-do makes you the most famous person in Coonabarabran at the moment?

Probably in Coonabarabran. Although I shouldn't think that very many of the citizens know that I'm here. There will be an article in the Coonabarabran Times [this] week, I think, to say that I've come to the United States to be a part of this.

But the Coonabarabran Times' circulation is very small, as you can imagine. So I'm not a big celebrity. And I don't really want to be, either. I'm just happy to give a bit of publicity to the telescope and to the people. I'm a part of a big team — it's a team that's done all the work.