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Planetary News: Cassini-Huygens (2004)

A Conversation With Linda Spilker Cassini Deputy Project Scientist - Co-Investigator On Planetary Passions, Girl Power, and Striking a Balance

Linda Spilker was born Linda Bies in April 1955 in Minneapolis, Minnesota. She earned a B.A. in physics from California State University, Fullerton in 1977. Following graduation, she landed a job at the Jet Propulsion Laboratory (JPL) working on the Voyager project. During that mission's downtime, she also managed to begin a family and continue her education. She earned her M.S. in physics from California State University Los Angeles in 1983. After completing her work on Voyager, she moved to Cassini in 1988, and four years later earned her doctorate, summa cum laude, in geophysics and space physics, from UCLA. She is Cassini Deputy Project Scientist and a co-investigator with the composite and infrared spectrometer (CIRS) team. Her husband, Tom Spilker, is a systems engineer at JPL, who is currently working on the Genesis mission.

AJSR: You have been with JPL for some time I know, long enough that when you started women physicists were a real rarity. What put you on - and kept you on -- that track?

LS: I have always enjoyed science, most especially studies of the stars and planets. My parents bought me my first telescope when I was nine years old. The first thing I did was to use it to look at Jupiter and its moons. As I was growing up I read many books about astronomy, our solar system and the missions that NASA flew to the planets. I always hoped that some day I would be able to work on NASA missions. For a while I even wanted to be an astronaut and go to the Moon!

In junior high and high school I took as many advanced math and science classes as they offered. I felt some pressure not to go into science because, at that time, it was not a field that women traditionally pursued. I was told that science would be too hard for me in college (even though I had done very well in all my classes!) I really liked science, however, and decided to pursue my interests in spite of what other people said. My parents also encouraged me.

I majored in physics in college. Actually, I started as a math major then switched over to physics and got my B.A. in that from California State University Fullerton. When I got out of school in the late 1970s, it was a great time to look for a job. I applied at JPL. In fact, JPL was number one on my list. I had always wanted to do something in astronomy or on the planets. I was offered two jobs -- one on the Viking extended mission [on Mars], and one on a new mission called Voyager that hadn't even launched yet. I asked where Voyager was going. They said: 'Jupiter and Saturn, and if all goes well, on to Uranus and Neptune.' That was a no-brainer. I was just launching my career, so it seemed appropriate to start with something new, and that's how I happened to become part of the Voyager mission. Of course, I hadn't thought through the risks of the launch itself. But, sure enough, several months later, I was down at the Cape [Canaveral] watching Voyager 2, the first launch, go on its way. I didn't look back from there.

Voyager, what a wonderful project to have worked on --

And, what a wonderful place to get started. I worked as part of the Voyager Infrared Team as the mission flew by Jupiter, Saturn, Uranus, and Neptune. That's where I got some background measuring radiant and reflected energy which was very useful. I also worked with the Voyager photopolarimeter (PPS) team that observed stellar occultations of Saturn's rings. As the star moves behind the rings, the amount of starlight that passes through the rings is measured, revealing detailed ring structure such as waves and wakes in the rings. That's what really got me hooked on Saturn and the rings. After we'd flown by Saturn, I went back to school and got my Master's at Cal State Los Angeles, in physics, and actually wrote a thesis in which I used some of the Voyager PPS occultation data. Then, as Voyager was making discoveries, I realized -- 'I really like this a lot.' I knew that in order to write my own proposals and direct my own course a little bit more, I was going to have to take that last big step and go back to school and get my Ph.D., which I did in geophysics and space physics at UCLA. That put me in a good position to do the job I'm doing now. And it was a good fit with Cassini too.

So you transitioned from Voyager to Cassini in the late 1980s?

Yes. I finished Voyager and started Cassini in 1988, even before they selected it as a mission. There was a little bit of overlap between the two. I worked on Voyager through the Neptune flyby in 1989, and at the same time was working on plans for Cassini. So, I've been with the Cassini mission for 16 years.

While most of us I think are generally aware of what a co-investigator does, what exactly does a Deputy Project Scientist do, what are the responsibilities of that position in the mix of a mission?

My responsibilities as Deputy Project Scientist are to maximize the science return and try to get the most science out of the mission that we possibly can within the Project constraints. We have both budget constraints and schedule constraints. And it is a challenge. Picture 'science' as filling up a big bag and you want that bag as big as possible, but within the size that the bag will hold. That's an analogy to what we try to do.

How did you / do you go about doing that?

First of all, quite some time ago we had to sit down and look at what kinds of science each team wanted to do, in each of the areas -- Saturn, rings, Titan, icy satellites, magnetosphere. Basically, we had each team put together a wish list of everything they'd like to do. Then we took those wish lists and began making trades or compromises between the teams, determining things like which target the spacecraft will look at? The reality is that you can't have every team doing everything they'd like to do. There are just not enough resources. For instance, we have one spacecraft. Now each team could probably take the spacecraft and use it full time, so you have to make the trades.

On Cassini, all of the instruments are fixed to the spacecraft. So we have to decide when exactly is the best time to look at Saturn or look at the rings or Titan and so on. You make those trades and then the teams have to decide how many resources they can put into actually designing the observations, telling the spacecraft where to point and that sort of thing since we have what's called distributed operations In distributed operations each team designs their observations and controls their instrument from their home institution, rather than having JPL do all of this work for them, as we did on previous missions such as Voyager and Galileo.

My job is to help coordinate the science activities and when it gets to a tough point where two teams both want something very, very badly, then it goes up to the next level -- which would be the Project Scientist level -- Dennis Matson. At that point, I work with him to try and come up with the best solution. Happily, we haven't had too many of those.

I would imagine making those tough decisions must be the hardest or least rewarding part of your job?

Yes, that's a very hard thing to do. What we usually do is ask both parties to make presentations to the entire science group, as well as to us, describing the scientific value of what they're trying to do and why this is a unique opportunity. In other words, is there a way we can maybe to do this observation someplace else in the mission? Could you take turns -- one instrument now and the other later? You review the options. But there are certain unique times in the mission where if two teams want to do something, you have to choose. You try to make a decision based on the value of the science that's getting returned -- how unique it is, and also looking back at the science that was discussed in the 'announcement of opportunity' - is this in line with accomplishing the major scientific goals that NASA put out?

Any specific example you could give where you and Dennis were presented with something that was a tough call?

Actually there was one extremely tough call. With Saturn Orbit Insertion (SOI), we had only one chance basically in the whole mission to fly above the rings and get the incredible resolution we did for the rings. There were two experiments that really wanted to make use of the time. In one of them the imaging team wanted to point their cameras down at the rings to look for clumping in the rings and they wanted to do it at a very specific time when we were very close to the rings. In the other one, the ion and neutral mass spectrometer team wanted to point its instrument's field of view into the direction of the incoming ring atmosphere to measure any gases that might be coming up from the ring and make a measurement of the composition of that material. Of course they also wanted to do this when we were close to the rings.

Both of those experiments were completely unique and SOI was the only time you could measure any ring atmosphere and its composition and the only time that you're really going to get in close to look in the A ring to search for these clumps researchers have been wondering about. It was a very, very difficult decision to make. It was finally made in favor of measuring the ring atmosphere, since that's what we call an in situ measurement where you have to be at that location to make the measurement. We decided in favor of the ion and neutral mass experiment (INMS) experiment.

Fortuitously, once the decision had been made, with a lot of hard work on the part of the science planners at JPL, we were actually able to come up with an orientation that would point the INMS instrument to look at the incoming ring atmosphere and also point the cameras down and take those pictures that they really wanted to get of possible clumps in the ring. Knowing that both kinds of science were valuable, the planners were able to come up an orientation that produced a win-win situation. It turned out that it wasn't even a compromise, but a position where you could accomplish both science objectives simultaneously.

I guess that was something of a relief?

Yes, and it would be nice if it could happen every time. But usually it can't, because often there are two very different targets the teams want to look at.

Are those decisions then made by you two at JPL or does NASA HDQ get involved?

No, NASA headquarters is really more concerned with the over-arching kinds of guidelines that they put forth in the 'announcement of opportunity' and worry more about whether we are staying on budget and that kind of thing. Now there is a Program Scientist back at headquarters -- Denis Bogan -- and he was certainly involved in science discussions and there were a lot of discussions that went on. The decisions are generally made by the team at JPL.

What is a typical day for you now?

It's kind of a balance, because I am also a co-investigator with the composite and infrared spectrometer team, the CIRS team. You can imagine my feeling torn on some days -- wanting to come in and spend my time looking at the data and the scans and things we got back from the mission and balancing that against the overall needs of the project.

As the ring lead for the CIRS team, I help coordinate with a number of people the schedule to make sure all of our observations get in on time and our instrument commands are delivered appropriately, and at a higher level, I help coordinate the activities across the science teams. Typically, as Deputy Project Scientist, I attend meetings that go on each day. We're down to the level where we look at each sequence in detail and we're still busy planning orbits. We'll finish up now in March or April. So, we're not only looking at the orbits we're flying in real time now, we're looking ahead and building sequences and so on for the orbits that are going to fly in the future. A lot of what happens now -- as you can imagine -- is outreach.

There is a lot of interest from the media to find out what's going on with Cassini, so there are lots of opportunities to do interviews and various things. For instance, today I talked with a staffer from the House Science Committee, who wanted an update on Cassini and I put together a little presentation to show him some of our latest results. Then there were actually some headquarters people visiting who wanted to see what MER and Cassini were up to so in the afternoon I spent some time with that group talking about the mission.

So you are conducting outreach in addition to your other two jobs?

That's right. That's why it's important for me to stay in close touch with the teams and understand their discoveries and their science, so when I do get asked to give an update on Cassini -- whether it's to a congressman or someone from headquarters or someone else -- I can do it as part of engaging the public and getting that information out. Tomorrow night, I will be giving a talk about Cassini's discoveries at a university that is open to the public, something that is also an important part of getting the message out - being able to say: 'Okay, here's the return on the tax dollars that were spent to put Cassini into orbit.'

And how many hours a day are you working now?

The days are really long days -- that's the answer. Easily, I put in 12-hour days, and sometimes I take work home with me. I have two daughters in college. One came home for the summer. It had been her first year away at college and she was expecting life to be back to what it usually was. I warned her ahead of time and had to remind her: 'I'm coming into a very busy time of my life. Please be understanding.' But sure enough, especially the week around SOI, and the time following it, I would get home really late and dinner was not on the table. At one point, she said rather forlornly to me: 'Mom, I feel like an orphan.' I felt really bad, but I said: 'Look, this is a once-in-a-lifetime kind of thing for me and life won't always be like this but this summer is going to be a little different." And all in all, she really has been understanding.

Given that you've been on this mission for 16 years, your daughters must have been born of Voyager and weaned on Cassini?

That's true. I tell my daughters, Jennifer and Jessica, that their births were really and truly based on the alignment of the planets. What I meant by that is that there was a five-year hiatus between Voyager's Saturn flyby and Uranus flyby, and I'll bet if you went back and looked at the Voyager moms in that window you would find we had a Voyager baby boom. I had my two daughters in that window. I was pregnant with my first daughter when Voyager 2 flew by Saturn. My good friend, Sue, and I both knew we were pregnant, but we weren't going to tell anybody until after the flyby was over. So we commiserated with each other. She had two sons, and our first-borns are two weeks apart and our second-borns are three days apart. We were on the same wavelength and the same cycle and we still laugh about that. Our kids sort of grew up together, went to the same schools together, and have remained good friends.

I met my [present] husband Tom while we were both worked at JPL on a NASA advisory committee. For our first date, we went to an astronomy club's dark sky site to observe Comet Hyakutake. I was really impressed with Tom because he let me operate his fancy telescope. I knew right then that I had a winner! Together we are a family of five -- he has a daughter from a previous marriage.

In October 1997, we took all three out of school for a week so they could see the launch of Cassini. Then, for the Saturn Orbit Insertion this summer, my daughters and my sisters and Mom and my husband and nieces and nephews were all at Pasadena City College (PCC) where friends and family were invited to watch the mission events. I was up at JPL for a little bit talking about the rings for NASA TV coverage, and once I finished there, I joined my family at PCC.

That must've have been a wonderful moment --

Tom, proudly told me after the fact: "When you came on the TV screen our little family group all started clapping and cheering." Then one of my friends said: "And the audience picked it up and they were all clapping for you." I was very flattered and thought that was a very nice gesture.

These missions to other planets really do have the power to touch people -

They do. I have a nephew, Andrew, who is in 5th grade right now and when I got over to PCC, he just sat right next to me and wanted to know about everything that was going on. Cassini was flying behind the B ring and so he kept watching the plot on the screen which showed us when we had radio contact with Cassini. I told him: 'We can't hear anything from the spacecraft, because it's behind the B Ring.' He kept saying: 'Aunt Linda, Aunt Linda, when will we be through the B Ring?' He understood that when we came out from behind the B ring we could get the signal back and know that Cassini was okay. He is already so interested in space and in the planets.

Just like you when your parents bought you your first telescope. Moments like that must be uniquely rewarding?

They really are. Not long after Saturn Orbit Insertion, Andrew had to give a little talk in school about people who had been a major influence in his life besides his parents. He talked about his aunt who worked for NASA on this big mission to Saturn and how he got to be there when Cassini went into orbit around Saturn. That was nice. His mom -- my sister, Jodi -- called me and asked me to give a talk to his class. I said: 'Of course, I would love to.' It's there, at that age, that you can inspire those who will go on to work in the space program.

Just how difficult is it to have both a career out there in space and a family life down here on Earth?

It can be quite challenging. There's no doubt about it. You've got to have a good support system, both in having a very understanding husband and also having a network of friends. My husband, Tom, works at JPL as well, and that can be good and bad, but certainly he understands the long hours. The network of friends is just as important. When my kids were in middle school, they would go over to a friend's house after school and she would watch them for a couple of hours. On the weekends, I would reciprocate if the other family wanted to do something or needed a place for their kids to stay. We traded and shared resources and that was invaluable. Plus, my Mom doesn't live too far away and when the kids were really little, she loved to take care of them. As the children got older, they started participating in after-school sports and that made it a little bit easier. But it is a challenge.

As everyone in the space business learns early on, this is not a 9 to 5 job no matter what job you do --

That's absolutely true. Even doubly true in these really hectic, active times when a mission arrives at its target, whether it's Mars or Saturn, or wherever. The nice thing about Voyager was that we had several months of high activity and then we'd have some down times -- peaks and valleys -- so that made it easier.

Striking a balance may be the most challenging thing you've ever done, but in a way being forced to find that balance may have made the moments more meaningful in a way or given you a break -

Yes, that's true, especially in being able to separate the two worlds. In high school my daughters were both involved in sports activities -- cross country, basketball, and track. A really big thrill for me was to go and watch them and to get to know the other parents. It was just a totally different place to be and I could be a 'mom.' One year, my youngest daughter's -- Jessica's -- high school basketball coach thought it would be fun to get a Moms team together, so the mothers could play the daughters. She had tried this one year with no practice for the moms and it was a kind of disaster because the moms didn't know what to do. So we spent the whole summer practicing every Sunday afternoon. I had an absolute blast. Before school started, we had our Big Game. Our team got stomped but it was really a lot of fun and that was sort of my way of balancing work and family life. If it meant leaving work early to see a game, then I would take work home or come in early then next morning, and I would do that just so I could be a part of their activities. In fact, Jessica, is now pole vaulting for UC Santa Barbara, and my oldest daughter, Jennifer, my youngest daughter's spent a couple of years doing crew and rugby at UC Davis.

Another point on striking a balance -- we have these big project science meetings three times a year -- two times here and once in Europe. As it happened, two of the European meetings fell on top of high school graduations for my daughters. That choice was easy. Fortunately, there was understanding on the part of the people here that graduation is a big event and I shouldn't miss it.

What is the most rewarding or fun part of being a part of the Cassini team?

Wow! Which one do I pick out? If there is only one thing I had to pick out, I think the most rewarding thing for me so far was watching those ring pictures come back after Saturn orbit insertion. I had been up the night before, watching us go into orbit, but I made sure to be back by 5 in the morning. I didn't want to miss a single picture. So much effort and time had gone into planning those pictures. It was a really special data set and I wanted to be there in real-time to watch them come back and watch history in the making. I was certainly not disappointed! The ring pictures were stunning, filled with details of waves and wakes in the rings, and all sorts of interesting ring features.

But there are a number of other rewarding things. I like sharing what NASA does, what Cassini does, with the public. I'm active with the American Association of University Women in supporting Career Days for middle school girls. That's very rewarding. If you can just inspire a handful, even one or two girls to convince them to stick with math and science during that really tough time of middle school. It is during those middle school years, when you lose so many girls who turn away thinking math and science is just too hard for them.

You mean, the Barbie™ can't do math syndrome -- ?

Exactly. That's a perfect way to put it. To try and reach out and convince some of these girls this is not the case -- that they, each of them can do basically whatever they want to do. They just have to believe in themselves and stick with it.

And you are living proof. You know one thing that always causes the public, journalists like me, and sometimes probably the team members themselves, to marvel is that after so many years in travel and at such a distant, dangerous place, the spacecraft arrives safely and goes through its tasks like clockwork . . .

You can never predict with certainty. We knew, for instance, that we were flying between the F and G rings, and we knew that place would be as safe a place as we could find. But something only the size of a marble in the wrong place, at the velocities we were traveling, would have been devastating for the mission. The good news is we got hit by these little tiny guys but nothing big hit Cassini. If there are marble-sized particles in that region, there aren't very many of them and they're really far apart.

A good thing to find out. With worries like that, how do you relax -- what do you do in your down time?

I really enjoy hiking and so does my husband, Tom. We can walk out our front door and up the street to a trail that leads to a little waterfall. There's another trail we like that as it ascends, it goes underneath some bay laurel trees, which are very, very pretty, and when you get up to the top of the ridge, you can look out on Monrovia. One of our more challenging hikes was on a glacier in New Zealand. We both also like doing more adventuresome things. We've both done some skydiving, bungee jumping, and whitewater rafting.

Yeah, I would say those are more adventurous, you must have the so-called 'dare-devil' gene?

Yes. I get a thrill out of challenging, new experiences. I'm also missing the fear-of-heights gene and so is my husband. For our honeymoon, we decided to go to New Zealand. We saw people bungee jumping off a bridge and decided that we wanted to try it too. When we got to the front of the line, I told my husband that I wanted to go first! He just laughed and said okay. After we each had jumped once, we decided to do a tandem jump, both of us at the same time, joined at the ankles. We also decided to dunk our heads in the water on this jump. We had a blast and even have a videotape to relive those jumps.

Speaking of 'wild and crazy' things, have there been any wild and crazy moments on Cassini, or any funny moments you'd like to share?

During the extremely stressful time just before Saturn Orbit Insertion people started dreaming about what might go wrong during SOI. One particularly funny dream involved terrorists stealing the Cassini SOI data before anyone could look at it.

Hmmm, imaginary terrorists in want of planetary data --

This person dreamed that somehow masked terrorists stole the bits of data flowing to the ground and that no one could find them or the data! Fortunately, everything worked out perfectly and the SOI pictures are there for everyone to enjoy.

Yes, and we're glad it did. At this point, what are you looking forward to most in terms of the science?

A couple of things actually. I'm really looking forward to the first close Titan flyby. There's a chance to unveil a whole new world. We have some hints of what the surface might look like, but certainly getting that first radar pass and really seeing what the surface looks like and really getting up close with Titan will really be exciting.

Then of course the follow-on in January with the Huygens probe release. To really get incredible detail in one spot on Titan's surface, and then to use the rest of the orbits we have, to try and put that picture in context, will be tremendously exciting. So far, what we have seen is just the beginning. I am really looking forward to many wonderful years of data return from Cassini.

Of course, I am really looking forward to new discoveries about Saturn's rings and to gaining a better understanding of the ring-moon interactions. I think that we will discover many tiny, new moons orbiting in between the A ring and F ring. I even have a bet with the project manager [Bob Mitchell] that we will discover at least 100 new moons. I hope that I am right!

This is one in a series of interviews exploring the people of Cassini-Huygens and the work they do behind the scenes to get these missions out there, safely, in space.