Q&A With Malcolm Hartley, Discoverer of Comet Hartley 2

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). (Image credit: NASA/JPL-Caltech, courtesy of Jonathan Pogson)

On Nov. 4, NASA'sDeep Impact spacecraft will make an up-close visit to the small CometHartley 2, marking just the fifth time ever that a comet has beenimaged from nearby.

It will be thesecond iceballencounter for Deep Impact, which served asmothership for a 2005 NASA mission that crashed a probe into CometTempel-1.

Comet Hartley 2 wasdiscovered in 1986 by astronomer Malcolm Hartley, who spotted itwhile poring over photographic plates taken with the U.K. SchmidtTelescope at Siding Spring Observatory, near the town ofCoonabarabran in New South Wales, Australia. [Photoof Comet Hartley 2.]

WhileHartley primarily studies galaxies and other phenomena beyond oursolar system, he discovered about 10 other comets — he has said hedoesn't keep a faithful log — in a similar fashion.

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

Where are yougoing to watch the flyby?

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

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

Are you excitedto get a better look at this comet than you were able to get back in1986, when it was just a streak in the sky?

That's right — itwas just a very faint streak. The discovery image was hardly there atall. I'm very, very excited about getting so close to it, andhopefully being able to see surface features on the comet. I hopethat we're going to get a lot of science out of it. It's extremelyinteresting. [Bestcomet images of all time.]

You studygalaxies, 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 todiscover one and to think that you've made that discovery. Everyscientist wants to make a discovery. And so to find something thatgets your name attached to it and will be there long after you'vedisappeared — that's great for you and your children, and yourgrandchildren and the people that follow.

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

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

My granddaughterwanted 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 wewere coming here [to the U.S.], she was desperate to go with me. Shethinks I'm flying to the comet. I explained that I wasn't actuallygoing to the comet, but she said, "Oh, we must fly — we mustall fly to the comet."

She's only three.Perhaps when she's 33 — who knows where she'll fly? [Top10 Private Spaceships Becoming Reality.]

Any predictionsabout what the flyby is going to show us?

Predictions arehard. Anything we get, any detection — both spectroscopically andvisually — will be very interesting in comparison with the otherfour comets that have been visited by spacecraft so far. It will bereally interesting to compare this with the Tempel-1imaging, and I just hope there are some features there that are arevelation in some way.

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

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

Well, I think, givenits size, there will be some interesting things we can learn fromthis one in particular. But building up a general sense is extremelyimportant. And the more comets that we visit, the more we'll begin tounderstand how they tick. And that would give us a lot of informationabout the evolution of our solar system. [Gallery:Solar System Remade.]

I'm not a solarsystem astronomer — I'm more galactic, extra-galactic. But it'sstill really exciting, and it's interesting to speculate and torevise and to learn more. And it captures the public imagination. Thethings NASA is doing are just mind-blowing, really. They can flybillions of miles and get within 700 kilometers of this object, whichis stupendous.

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

Yes, as part of thequality 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 itusually has a kind of halo around it. This one was quite faint.

Really, the way thatwe found comets on the U.K. Schmidt survey plates is kind of byaccident. We were looking for interesting things on the plates. Andone part of my job was to do that. So if there is a comet or afast-moving asteroid or something like that on the plate, you'd takespecial note of it.

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

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

A telegram? Itseems crazy that that was the technology used to alert people backthen. It wasn't that long ago.

Yes, telegrams inthose days. A little piece of paper.

When are yougoing 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 anddancing by then, I think.

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

Do you reckon allof this to-do makes you the most famous person in Coonabarabran atthe moment?

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

But theCoonabarabran 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 thepeople. I'm a part of a big team — it's a team that's done all thework.

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Mike Wall
Senior Space Writer

Michael Wall is a Senior Space Writer with Space.com and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.