By Gail Jacobs
Dr. Ignacio Mosqueira is an astrophysicist at the Carl Sagan Center for the Study of Life in the Universe, SETI Institute. He works with Paul Estrada to piece together the way in which giant planets - such as Jupiter and Saturn -- and their moons and rings formed. Ignacio notes that making moons is similar to forming planets. Understanding moons may have something to tell us about the possible habitats for life, since large moons could, in principle, have both the liquid water and atmosphere necessary for the kind of diverse biology we see on planet Earth. Ignacio joined the SETI Institute in 2002.
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Ignacio, you're an astrophysicist. In layman terms, explain what that means.
Simply put, an astrophysicist studies celestial objects and the universe using the laws of physics. However, nowadays physicists also tackle such questions, so the distinction between the two disciplines is becoming blurry.
Describe your research project.
My project takes on the big question of how planets orbiting Sun-like stars form and attacks it from a particular direction. We're studying the origins of the moons of giant planets. We're essentially following on Galileo's trail. At the time of Galileo's discovery, Jupiter's moons proved that not everything revolved around the earth. Galileo immediately recognized the moons' significance. One could say he found a system of smaller planets revolving around Jupiter, which can be thought of as a "mini-solar system."
My current research is focused on Jupiter's and Saturn's moons and rings. We want to figure out how they fit into the history of the planets orbiting the sun -- how planets formed and in what order, why they have the properties they have, and so on. These questions are important because the answers can help us learn much more about the earth and its place in the solar system. Having only one example of anything makes it difficult to draw any conclusions from it - and this also applies to the solar system. What moons can offer us, however, are other planetary systems from which to learn. Although the largest moons are the size of Mercury -- a small planet -- we can still learn a lot from them. As an analogy, imagine you want to learn about a tiger but you have a house cat. Studying a house cat can actually tell you a lot about a tiger. And the more species of cats you study, such as a cheetah, a jaguar, a leopard, and so on, the more you can learn about which behaviors are specific to house cats and which are common to all cats, including tigers. The fact that there are many moons is very useful to us. It helps us to learn a lot more about planet formation.
is nearest Jupiter; then Europa (center); Ganymede and Callisto (lower right).
Image credit: NASA
One question I find really interesting involves the likelihood of planets around other stars resembling the earth. How common are they? If you don't understand planet formation, you have no idea. Maybe there are very few Earth-like planets and we live in a very special place. But is it special for us, because we happen to live here, or truly unique?
The solar system is like an intricate puzzle. The moons, planets and the sun don't function independently - they all work together. Scientists focus on one piece at a time. But in the end all the pieces must fit together to form a majestic picture of our place in the universe.
How did the specific study of moons attract your attention?
The problem that attracted my attention to this field was that of trying to explain the internal structure of Callisto, Jupiter's second largest moon. We know a good deal about the earth's internal structure. If you searched for a mountain made entirely of iron, you wouldn't find one. It couldn't exist because iron is so dense that the mountain would actually sink. When the earth formed, the iron sunk to the center of the planet, creating a core. So while we understand that principle for the earth, how does it apply to the largest moons? Do they have either metallic or rocky cores? And what would this tell us about how they formed? Callisto gave us a big surprise because we were expecting to find a core and no core was found!
How did you feel when you learned of Callisto's "surprise?" Was it a setback?
Not at all -- quite the opposite. A surprise is often much more instructive and more fun than a confirmation of something you already know. You think you understand something, you're familiar with it, and then you find out you have to rethink it. It's really great. Otherwise planetary scientists would still be insisting that Callisto must have a core and would learn nothing from this assumption. Luckily, this new information presents us with a deep mystery we must solve.
What is the coolest thing about your project?
There is a lot of interest in moons and planet formation right now because of the earlier Galileo and now the Cassini spacecrafts. The results from the Cassini mission to Saturn are radically changing the field, and that's really exciting. The coolest thing is that we are in a position to think about the meaning of these results when they are hot off the press.
What do you currently consider your biggest challenge?
The biggest challenge is in selecting the right problem to tackle. There are many directions to pursue, and it's important to choose a problem in which you can make progress. And it's equally important to select a problem that I'm interested in so I will be motivated to work on it. There isn't a formula you can use to select the right problem. You just try one for a while. If you're not making progress, you move on to something else.
Why should the general public care about your research?
We're now finding planets around other stars, and that's a topic many people are interested in and care about. It is important to move beyond our provincial geocentric point of view. For instance, the earth's orbit around the sun is almost circular. Is that typical of habitable planets orbiting stars other than the sun? If we inhabited a planet with an eccentric or squashed orbit, our day-to-day life would be totally different. We would sometimes be very close and sometimes very far from the star. What sorts of planets are possible? And what would it be like to live there?
Image credit: NASA/Tim Pyle
An astrophysics background also helps when considering climate change or mankind's future energy sources. To give you an example, electric car batteries use the element lithium. It's important to know where lithium comes from and how much of it we have. Most elements were created in the interior of stars or during the explosion of stars. Lithium actually comes from the big bang when the universe came into being. So it turns out that, in addition to explaining why we are here in the first place, the big bang has a very practical consequence for all of us. If you're going to find the solution to a problem, you first have to first understand the problem. A prominent astrophysicist by the name of Frank Shu has been spending time pondering our energy future in a carbon-constrained world. He comes to the conclusion that thorium may play a key role in moving us forward. I think it is important that scientists address pressing social needs when they can. In my view, Frank Shu is making an important contribution.
What first sparked your interest in science and astronomy in particular?
I grew up in Madrid, and I read Carl Sagan's Cosmos in Spanish. Carl had a big influence on a lot of planetary scientists, including me. More than anything, I was struck by his way of looking at the world. That was the power of the book and the TV series. One passage that stuck with me has nothing to do with astronomy, but involves crabs with scolding samurai faces etched on their shells. I vividly recall Carl telling the story of a battle between samurai clans that resulted in the death by drowning of the defeated child-emperor and his entourage. By returning mean-looking crabs back to the sea and eating the others, Japanese fishermen selectively bred the crabs to resemble samurai without realizing it. I find this story quite compelling. One of these days I'll definitely have a look at those crabs for myself. But however beautiful the idea may be, science is about ideas surviving facts. And it is not clear that crab shells got to be that way for the reasons Carl suggested. And that's the challenge of the dissemination of science. Ideally it should be both inspiring and true.
What keeps you motivated?
I'm motivated by the challenge of continuously having to figure things out. Every day I need to think about how I'm going to make progress. It's no small feat to advance knowledge and then to get your ideas across.
What was your dream job as a child?
Like many kids, I wanted to be an astronaut. I wondered what it would be like to live on Mars. But I'm no longer motivated by the desire to travel to Mars. I'm from Earth, and happy to remain Earth-bound. Instead l let my mind do the wandering.
If you were speaking to a group of teens about your career, what would you tell them?
To have a successful career in science, you need to be self-directed. You can't wait for people to tell you what you should be doing. That's not what the job is about. A scientist needs to come up with problems that are important and then pursue them. One also should be able to communicate the significance of the problem. At times you need to be a bit of a salesperson and sell your ideas. You need to be persevering and not buckle under the competition. If you don't have the motivation, you won't make progress on the subject.
You teach "Introductory Astronomy" at San Jose State University. What is it you enjoy most about educating young adults?
I enjoy it when students who are not scientifically inclined are willing to come to talk to me during office hours or do whatever it takes to develop a sense of the subject. It's not when you teach someone who is already interested that's truly rewarding -- it's when you can instill an interest in astronomy.
You're also a playwright.
I've written several plays and I had a role in one that was performed in San Francisco. I'm a good writer but a lousy actor. I wrote the plays as character studies. I'm keenly interested in how people behave and why they do the things they do. A book that greatly influenced me was Remembrance of Things Past by Proust. I also like Ibsen's plays. If I weren't doing science, I might try to stage a production of Hedda Gabler. One of the challenges is to find the time to do everything I'd like to do. Science and writing are full-time occupations, which makes it very difficult if not impossible to do both at the same time.
How do you spend your remaining free time?
I write. I play in a soccer league, and I run. I also like to travel. This summer I'm looking forward to traveling to two of my favorite destinations - Norway and Spain.
What is your philosophy of life?
Don't accept handed-down wisdom uncritically. There ought to be an element of the rebel in a scientist. Over the course of history, scientists have gotten into trouble over and over again for accepting imposed knowledge. Aristotle said all planetary orbits had to be circles; and because he was considered the authority, his opinion was accepted as fact for a long time. This same tendency still goes on today. There are always pressures external to science, and the incentive is there to manufacture consensus even when it is unwarranted. Scientists always have to guard against falling in this trap.
What is your favorite vacation destination?
My father was an airline pilot so I had the opportunity to travel extensively, including several places in South America. When I was young I had quite an adventure at Volcan Poas in Costa Rica. My brother and I decided we wanted to check out an active volcano. From the visitor's area, we made our way to the rim of the volcano through the thick and muddy jungle. The caldera looked to be a place we could easily walk on. At the bottom, we could see several bubbling cauldrons. Having too much curiosity and too little common sense, we decided we wanted to get a closer look.
Poas Volcano crater in Costa Rica
We soon found out that volcanic ashes are anything but firm. As soon as we stepped within the caldera, the surface turned into a muddy slide. We slid down the side of the volcano and finally slammed into a pit filled about knee-high with water and mud instead of sulfuric acid, or we would not be here today.
We then had to figure out how to get out of there. We decided to take turns digging into the ashes and mud using our fingers as crampons. Then we used each other's bodies to slowly climb out of the hole we had put ourselves into. By the time we crawled out of the volcano, and slithered through the muddy jungle and back to the visitor's area it was already twilight. Costa Rica is justly famed for its biodiversity but more than one visitor thought he had come upon an entirely new species of primate prowling in the gloaming! And that's the scientific spirit!
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