Heidi B. Hammel, 48, an M.I.T.-educated planetary astronomer, has two professional missions. The first is to learn everything possible about those icy planets, Neptune and Uranus. The second is to communicate knowledge about space to ordinary citizens. In 1994, when the Shoemaker-Levy 9 comet crashed into Jupiter, Dr. Hammel was the leader of the ground team that analyzed photos of the event from the Hubble Space Telescope. At the same time, she was the National Aeronautics and Space Administration’s public face, explaining the science to television audiences worldwide. We spoke at her home in Ridgefield, Conn., and later by telephone. An edited version of the conversations follows.
Q. NASA IS PREPARING A MISSION THAT WILL DO ONE LAST REPAIR OF THE HUBBLE SPACE TELESCOPE. AFTERWARD, IF HUBBLE MALFUNCTIONS, IT WILL BE ALLOWED TO DIE IN SPACE. DOES THAT TROUBLE YOU?
A. Listen, much as I love Hubble, it’s time to build new tools to see new things.
I’ve been working with a team planning the next great space observatory, the James Webb Space Telescope, scheduled for launch in 2013. Webb will be able to probe regions of the cosmos that are simply not visible to Hubble. It’s bigger and it will be tuned to wavelengths that Hubble can’t really see. With Webb, we have the potential to answer questions about the origins of just about everything in the universe.
Q. WHY DOES IT HAVE TO BE HUBBLE OR WEBB? WOULDN’T ASTRONOMERS LIKE TO HAVE BOTH?
A. There isn’t enough money to do everything. Hubble’s already lasted much longer than people expected. It wasn’t meant to last forever.
Q. LET’S TALK ABOUT YOUR SCIENCE. DO YOU THINK ASTRONOMERS ARE SOMETHING LIKE DETECTIVES — OR INVESTIGATIVE REPORTERS?
A. I think all scientists are like detectives. We are most happy when we find something that doesn’t fit our expectations. My work often involves analyzing images of the planets taken by Hubble or made at Earth-based telescopes like the Keck in Hawaii. If I see something that seems out of sync with what’s already known, the first thing I do is try to find out what’s wrong with the data. Once you’ve done that, and it still seems wrong, that’s when things get interesting. It means you’ve found something new to understand. So you think about it and go for more data and come up with different models. All real science is like that.
Q. CAN YOU GIVE ME AN EXAMPLE OF THIS FROM YOUR RESEARCH?
A. In 1989, when Voyager 2 flew by Neptune, we saw, for the first time, a great dark spot in that planet’s southern hemisphere. I went to an Earth-based telescope to look at it in real time. Well, lo and behold, the dark spot wasn’t visible. All I could see were these bright clouds alongside where the dark spot was supposed to be.
Then in 1993, I looked at Neptune again and all the bright stuff was now in the northern hemisphere. A year later Hubble sent back Neptune images, and on those pictures the southern dark spot was definitely gone. So far, it hasn’t come back. We don’t know why.
But we did learn something new: that Neptune could change dramatically in just five years. Till then, it was thought that Neptune was more static.
Q. YOUR EXPERTISE IS NEPTUNE AND URANUS, GENERALLY THOUGHT TO BE THE DULLEST PLANETS IN THE SOLAR SYSTEM. WHY DID YOU PICK SUCH UNCHARISMATIC BODIES TO STUDY?
A. They are not dull. They change a lot. But yes, they are the Rodney Dangerfield of the solar system — they don’t get respect. What are they called? “The Icy Giants.” Actually, they are great for a researcher. Because they are located at the outer reaches of the solar system, they’ve been less studied than nearer planets. So whenever I make an observation, anything I find is brand new.
With Uranus, now we’re rewriting the textbooks on it. Our recent observations are so counter to what we thought. We are going through a different season right now on Uranus, and the whole planet’s atmosphere is turning on, bright clouds, great dark spots, all sorts of convective activity, which 20 years ago we didn’t see. We thought of Uranus’s atmosphere as pretty much dead. And it’s not.
Q. THOUGH IT’S NOT YOUR PLANET, HAVE YOU BEEN FOLLOWING THE RECENT NEWS FROM MARS?
A. Yes. And it’s very exciting. The soil is good. There’s ice. There may be places where the ice is more accessible. It means that there aren’t physical reasons to stop us from colonizing that place, if that’s what the fate of humanity is going to be. We are finally being able to determine what Mars is made of.
I try to stay on top of the Mars findings because at some level the solar system is unified. Things that happen in one part are relevant to other parts. The chemistry on the Mars surface informs our understanding of the chemistry elsewhere in solar system.
Q. ARE WE GETTING ANY CLOSER TO DISCOVERING POSSIBLE LIFE OUTSIDE THE SOLAR SYSTEM?
A. That’s become a fun question now that we’re discovering planets around other stars. I have this widget on my computer that gives me a running total of how many new extra-solar planets have been found. It’s over 300. Most of them were located in the past few years, and the pace of discovery is accelerating.
We have to take it one step at a time. The first step is to locate an Earth-size planet the right distance from its own star for water to have been in liquid form long enough to allow life, as we know it, to develop. The next question will be: How can we tell if life is present, because this body will be too far away to take pictures of it? We will have to look at the chemistry of its atmosphere and look for signs that it has been modified by the presence of life. That will be the clue.
Q. HOW DID YOU DEVELOP YOUR TALENT FOR EXPLAINING SCIENCE IN POPULAR TERMS?
A. My Uncle Larry was my template. When I was a student, I’d come home on Thanksgiving weekends, and during breaks in his football game he’d go, “O.K., Heidi, whatcha workin’ on?” I knew I had 30 seconds to tell this guy who worked in a Mack truck factory what I did. He just wanted the big picture. I’d quickly say, “I’m using big telescopes to try to find planets and figure out what they’re made of.” Every scientist should be able to do that.
Q. YOU DO YOUR ASTRONOMY FROM A HOME OFFICE. HOW DO YOU MANAGE THAT?
A. All you need is computers and high-speed network contact. I’ve got one computer that’s connected to the Internet and another one that’s walled off from it. One is for data analysis and the other is for e-mails.
Q. HOW DO YOU KEEP YOUR THREE YOUNG CHILDREN “WALLED OFF” FROM YOUR WORK?
A. They and my husband have had to learn that when my office door is closed, it’s closed. I’ve had to learn how to prioritize. You have to budget time for the inevitable problems that come up with children. You have to always be ahead of the game. If your proposal is due at NASA on Friday, it has to be finished on Wednesday because, on Thursday, it could be fevers and head lice.
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