Leading Us to Asteroids
Carol Raymond is the deputy principal investigator for the Dawn mission to study the dwarf planet Ceres and the asteroid Vesta. Dawn is the first mission to orbit two asteroids.
What is the role of the mission deputy principal investigator?
The deputy principal investigator assists the principal investigator in leading the mission. I also am the day-to-day interface between the science team of the mission and the engineers and technical people who are responsible for implementing the mission. So, I am a team member who tries to integrate the outside science elements with the JPL and the distributed team that is putting the mission together.
How did you get interested in planetary science in general and asteroids in particular?
In my early career work as a marine geophysicist, I studied the Earth's magnetic field as recorded in the volcanic rocks on the ocean floor and motions of the Earth's tectonic plates. After studying all of the aspects of the Earth's magnetic field, the tremendous discovery of the magnetized crust on Mars was revealed. That opened up a whole new area of research for me. I began looking at the differences between magnetic field generation on the Earth and on other planetary bodies, and what it reveals about how they developed. It was then not a large leap to decide to look at the evolution of other planetary bodies, including the asteroids.
Now on the Dawn mission, we are no longer going to be studying the magnetic fields of the bodies. But their internal evolution can be revealed by other means, for instance, gravity, data, the topographic data, and what has ended up on the surface of the bodies as a result of their geologic evolution. So, I have come to the Dawn mission by a fairly long and sometimes convoluted road, but I am very happy to be part of it. It is a very exciting mission.
How has the field of planetary science changed since you first entered it?
The field of planetary science has experienced a rapid growth since I first became interested in it. Planetary science is moving from an era of reconnaissance missions, in which we visited all of the planets of the solar system except for Pluto, to one where we're planning highly detailed observations and investigations. This includes some time in the future where we plan to actually grab samples from these bodies and return them to Earth.
Of course, Earth is a planetary body, but the approach to studying the Earth is somewhat different in that we know an awful lot about how the Earth has evolved and we're now trying to study some of the processes that shape the Earth in detail. Whereas when we approach other bodies, we know so little that we are really trying to work out the fundamentals of how these bodies were formed, how they evolved, and what things on the surface tell us about processes in the interior. It is a very different approach to studying.
So, we are on the verge an explosion of knowledge of what makes up the other bodies of our solar system - how they evolve and how the whole solar system has evolved over its more than four billion years of evolution.
Explain plate tectonics:
Plate tectonics is the study of how the Earth's surface moves and how new material is created from magma that erupts from the Earth's interior, and is destroyed as material sinks back into the interior on a planetary conveyor belt. Basically the Earth is covered with a series of plates, both large and small, and they all move relative to each other. You can think of the plates on the Earth as a thin crust that forms because of the coolness of the surface vs the heat of the interior. So the plates are riding on a much warmer and yielding "gooey" layer, sometimes called substrate. They bump against each other; they slide; they go under each other; and they also spread apart where material comes up from the interior. The material inside the Earth is convecting so that the warm material rises under the mid-ocean ridges. When it gets cool, it sinks in the broad subduction zones where plates collide, mountains are built, and the weaker plate is forced back down into the warm interior in the subduction zones. You can think of it as the way that the Earth regulates its heat from the interior to the surface.
It is also a very important part of why the Earth is different than other planets. In addition to having a heat cycle, there is also a cycle of chemistry wherein material from the surface that's rich in water-bearing minerals is going back into the deep interior of the Earth. It's bringing the water with it and it turns this whole engine - similar to when you put a little water in a blender with a bunch of stuff in it - it starts to turn a lot faster. So we have a really interesting situation on the Earth where we have a lot of water and the water is in the atmosphere, it's in the oceans, and it's also in the interior. That seems to be one of the ingredients that make the Earth as a planet different from some of the other planets like Mars.
Outside of your expertise in planetary science, can you share with us any other area or field of interest?
There are other applications to the work that I do. One other area that I have been quite interested in is studying the interaction of planetary bodies with the solar wind or the wind streaming off of the sun, which is buffeting all of the bodies in the solar system. Magnetic fields of planets basically create a shield against this stream from the sun and that shield protects us from harmful radiation and other effects. So, studying the magnetic field is a way to trace some of the processes of that interaction between the planetary bodies and the sun.
How does the term magnetosphere apply to solar wind study, and do Ceres and Vesta have magnetospheres?
The magnetosphere is that cocoon that the Earth lives inside of; it is the boundary between where the solar wind streams regularly away from the sun, and the obstacle that the Earth's magnetic field presents to it. You can look at it as kind of a pressure boundary between the magnetic field of the Earth, the magnetosphere which is protecting the Earth, and where it no longer has any effect.
We don't think that Ceres and Vesta have magnetospheres. But the interesting thing is that in the past, Vesta in particular may have had a magnetosphere, because some of the meteorites that come from Vesta have some magnetic material in them, indicating that the protoplanet may have had a field of its own in the past. We know that Mars had a very strong magnetic field in the past and therefore should have had a strong magnetosphere, and we know that Jupiter also has a very interesting magnetosphere. So we have a lot of planets in the solar system that have or have had magnetospheres in the past.
There are so many asteroids out there and lots of meteorites. How would you identify one that came from Vesta?
The way that we know that some of the meteorites that have fallen on the Earth have come from Vesta is by matching the spectra of the minerals in the meteorites to spectra of Vesta that we have obtained with telescopes. A spectrum is basically a signature of the minerals that are in the rock. You obtain it by looking at the radiated energy coming off of the rock. You get certain peaks, which correspond to certain minerals in the rocks. This is a very unique signature. Now when we look at Vesta with a telescope, even though we don't have tremendous resolution of that signature - it's a little bit fuzzy - there has been a confident match made between the spectra from the body itself, way out in the solar system, and the pieces that have fallen on the Earth. This connection is now fairly well established. It was first made in 1970 by one of our team members, Tom McCord, who was at the University of Hawaii (where he's spent most of his career). He now splits his time between Hawaii and Washington State.
What is it about your work on the Dawn mission that you find most exciting?
Working on the Dawn mission is very exciting because it presents a lot of challenges, and of course along with great challenges come great rewards. Some of the things that really interest and excite me are making the mission happen. It is so wonderful to take something that you conceptualize and then start to go through the process of turning it into a reality. Every step along the way there are decisions to be made. A lot of work has to be done to get all of the details taken care of. There is a tremendous sense of accomplishment when you actually work through each step of the mission and see the final product take shape.
You mentioned challenges and noted that "with great challenges come great rewards." In your opinion, can you identify some of the great challenges of the mission?
Some of the large challenges in working on the Dawn mission are first of all simply getting the spacecraft with all of its instruments to the launch pad on time. There is so much work that goes on to put it together; it's a daily grind. Basically, it's a lot of work, and a lot of people working together. Problems continually arise and you have to solve them. You are in a constant problem-solving mode from the beginning of spacecraft design until getting to the launch pad.
Then, we have the job of planning how to operate that spacecraft. Once it launches, we have to get to know it. It's going to have a personality. We have to figure out how to make everything happen smoothly, how to keep the spacecraft happy, and how we are going to get all of the science data that we want. We want to squeeze every drop of data out of the mission. We're going to be constantly studying and optimizing how to operate the spacecraft. Once we get the very rich data set, we'll have to work with it, getting it all analyzed and published. It's such a vista of opportunity for science that it's hard to convey how exciting it is.
If you are the deputy principal investigator located on the west coast, and Orbital, the builder of the Dawn spacecraft, is located on the east coast, how closely can you work together to ensure that that spacecraft is going to be ready to perform its duties?
The Dawn team is distributed all over the globe. We have the Orbital Sciences in Virginia. We have the team building the framing cameras in Germany, and the team building the visible infrared spectrometer in Italy. We have Los Alamos Laboratory building our gamma ray neutron spectrometer and we have team members from universities and institutions in both the United States and Europe. So the team is distributed across about 12 time-zones. We have to interact with each other in a very methodical way. We have lots of telecons, where we are getting up early in Pasadena and everybody in Europe is getting ready to go to bed, and then we have the East Coast in the middle. But this will work as long as everybody's committed to it. The other enabling factor is, of course, the Internet, where we can exchange our files and information effortlessly. Another important aspect of running a mission with a distributed team is to write it down. You have to have documents. You have to have a very formal way of letting everybody know what is expected of them. One of the things that I discovered working on the Dawn mission that I didn't fully appreciate is how important the rigor and the methods are in success for these missions.
In your opinion, what new science understanding will the Dawn mission provide?
I believe that the Dawn mission is going to teach us a lot about how the inner solar system - the terrestrial planets - evolved differently than the gas giants in the outer solar system. Jupiter and Saturn have very low densities; they are gas planets. The inner solar system consists of rocky bodies. In the transition between those two major types of bodies in the solar system lies the main asteroid belt. Within the main asteroid belt, we have identified two of the largest objects, Vesta and Ceres, where we have the same sort of fundamental differences. Vesta being a higher density, more rocky body and Ceres looking like a much lower density body that has a lot of water in it. So, we are looking at this fundamental boundary within our own solar system - how the material changed and evolved at the very start of our solar system. We believe that we are going to learn something fundamental about the beginning of the solar system by comparing and contrasting these two bodies.
How long have you been at the Jet Propulsion Laboratory and what is it like to work at a space science research laboratory?
I have been at JPL for fourteen years. It is a very unique place to work. There are about 5,500 employees, of which about 500 are scientists. It's an enormous machine that is very well honed, and the Lab produces some of the most innovative work that is going on in our country. It is a tremendously exciting place to work. One of the aspects that I like best is that in addition to having a lot of scientific colleagues whom I highly value, I also get to interact with engineers, all manner of technologists, and people who know how to get things done. It is a very fertile, high-paced environment, and one in which you can really innovate and achieve things that are sometimes inconceivable. I have heard from people outside the Lab that they just can't believe what people do there. It's true, and there are lots of times that I can't even believe the things that people do. Having that environment where you have all this activity going on around you really enables you to reach a potential that is just fantastic.
What have you found to be the most fascinating thing in your work in the Dawn mission?
One of the most fascinating things for me about working on the Dawn mission is finding out, in great detail, about all of the different aspects of science that we are trying to accomplish on the mission. As it turns out, almost all scientists specialize at some point early in their career. They focus on a few problems that they have spent a lot of time studying. However, this mission is so comprehensive that there is a wide range of different methods that we are using to study these two bodies. Now I am learning a tremendous amount about fields that I wasn't familiar with and I know that I will emerge having learned a tremendous amount. To me, that is one of the huge benefits of working on a mission like Dawn.
What kind of advice would you give to a young person who is considering a career in the field of planetary science?
Start with the basics. Math is very important, but there are a lot of other skills that one can and should have to be successful. Begin with a curious mind, very strong communication and writing skills, and be able to be objective. Then, after getting a good education, don't be afraid to follow your own idea from its conception to reality. Science is one field where you can really make unique contributions, where you can really have your own path through life. It is a wonderful feeling to be able to conceive of an experiment, carry it out, and feel that sense of accomplishment when it's done. And that aspect, plus the inedible tremendous teamwork that goes on in carrying out a complex science experiment or a mission, is another aspect where you really make life-long experiences and achievements. So, my advice would be that if you want some adventure, if you want to work hard, if you want to do work with teams, ...if you want to see an idea from conception through its ultimate goal, science is a wonderful field to work in. It is highly rewarding.
With your experience as a woman in the field of space science, what kind of advice would you offer to a young girl who aspires to enter this field?
I would advise any girl who is interested in doing independent science research or technical work to remember that competition is all around you and to succeed you have to compete. One of the qualities that many successful women I know have is that they were very competitive in sports or they had some other aspect of their lives that let them build confidence and believe in themselves. I think that is one of the important aspects of becoming successful in any field - but particularly in science, where you really have to depend on yourself to get your programs started and to be successful in them.
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