NASA Science Mission Directorate
Oral History Project
Edited Oral History Transcript
Steven W. Squyres
Interviewed by Sandra Johnson
Ithaca, New York – 22 August 2017
Today is August 22, 2017. This interview with Dr. Steven Squyres is
being conducted by the NASA Headquarters Science Mission Directorate
Oral History Project. Dr. Squyres is speaking with us today by telephone
from New York. The interviewer is Sandra Johnson. I want to thank
you again for agreeing to talk to us, and fitting us into your schedule.
I know you are busy.
I wanted to start today by talking about your background and where
your interest in, first of all, geology, and your eventual interest
in working with NASA came from.
Sure. I have always been a scientist. I can’t remember a time
in my life when I didn’t consider myself to be a scientist.
When I was six years old I wouldn’t have told you I want to
grow up to be a scientist. I would have told you I was a scientist,
I just wasn’t a good one yet. So I can’t point to the
origin of my interest in science because I cannot remember a time
when I didn’t have it.
I was very fortunate in that both of my parents were scientifically
trained. My father got a doctorate in chemical engineering from MIT
[Massachusetts Institute of Technology, Cambridge, Massachusetts];
my mother got a bachelor’s degree in zoology from Wellesley
[College, Massachusetts]. So when I was a kid growing up, for all
the physical sciences questions, I went to Dad; for all the life sciences
questions, I went to Mom. So I grew up in an environment where science
just kind of permeated my thinking. There was never a time when I
didn’t plan to be a scientist professionally.
The other thing that I loved when I was very young, and still do today,
was climbing mountains. I grew up in the flatlands of New Jersey,
but my family visited Colorado, the Colorado Rockies [Rocky Mountains],
when I was eight years old, and I just absolutely fell in love with
the mountains. Being outdoors in nature, being out in the mountains
and doing science were two things that I loved from my earliest memories,
so it always seemed to me to be a natural thing to want to do geology,
because it was a chance to go out and do science out in the mountains.
Now, when I was young, I was interested in all sorts of different
kinds of science. But by the time I hit age 18 or so, I had pretty
much settled in that geology was something that I wanted to do. I
was very fortunate in that the summer that I was 18 years old—the
summer between my last year of high school and my first year in college—I
was able to participate in a research program, a research expedition,
on the Juneau Icefield in southeast Alaska. The National Science Foundation
provided fellowships, scholarships, for this sort of thing.
I applied and was selected for the program, and it involved doing
an entire summer’s worth of geologic fieldwork. Most of my work
actually wound up being in northwestern British Columbia, but it was
out in the mountains doing science every day. I just fell in love
with it. It was just absolutely fantastic. I’m doing scientific
research, I’m climbing up and down mountains, it just seemed
like everything I wanted to do.
That was the direction I was planning to go when it came time to start
my college career. I was an undergraduate student at Cornell University
in Ithaca, New York, where I teach today, and became a geology major
here. It went well at first, but after a couple years I began to become
somewhat dissatisfied. The reason was that what it lacked, to me,
was the element of exploration.
One other thing that always—always—captivated me as a
child—and this is going back, again, to age 8, 10, 12—was
I was always fascinated by exploration. I read and read and read books
about early explorers. The Arctic, the Antarctic, underwater exploration—I
was captivated by that stuff from a very early age. I grew up in the
late ’60s, and this is when Mercury and Gemini and Apollo were
going on, and I was transfixed by that stuff. I can remember—gosh,
I would have been—when was John [H.] Glenn [Jr.]’s [orbital]
Yes, that’s right.
Yes, ’62. Six years old, I was glued to the television set his
entire flight, just captivated. I can picture it, where I was sitting,
like it was yesterday. Gemini, Apollo—I was just absolutely
fascinated by all that stuff. For me, the notion of being a scientist
and the notion of being an explorer were always intertwined.
What happened was I got to Cornell, I spent a couple years studying
geology and learning, but it began to feel somewhat dissatisfying
for me. Because what I came to realize was that the geologists who
have been working on this planet for a couple of centuries have done
a pretty good job of figuring a lot of the stuff out.
I don’t want to give the sense that I think of geology as just
being filling in the details. There’s all sorts of fascinating
work to be done in the geosciences, and there will be for centuries
to come. But to me, it didn’t have that element of the unknown.
It didn’t have the element of the unexplored, and that was something
I very much wanted.
After a few semesters, I began drifting towards doing something on
the seafloor. I wanted to do something on the Earth’s seafloor,
marine tectonics kind of stuff, study of the geophysics and geology
of the Earth’s seafloor. And then—and oh, I remember this
so vividly—there is this wonderful, terrible map—“wonderful”
in terms of the work that was done, “terrible” for me—that
came out. It was the first really good map of the Earth’s seafloor,
and it was done by [Bruce C.] Heezen and [Marie] Tharp. It came out
in, I want to say, ’77, something like that. Everybody’s
It was the first map really put together—it was done, I think,
at Columbia University [New York, New York]—showing the physical
geography of the entire Earth’s seafloor. It was a beautiful
piece of work, and the minute that came out it went up on the wall
prominently in every geology department in the world. I remember looking
at that and saying to myself, “Oh, crap. Now what?” There
it was, all mapped out. That map, magnificent piece of work that it
was, was the last straw in driving me out of terrestrial geology.
What happened then—I was very fortunate. This would have been
my junior year, my third year at Cornell. I had a hole in my schedule,
in my course schedule. There was a language requirement at Cornell.
I had just barely squeaked by a good enough score on a test, and so
there was a semester of Spanish that I thought I was going to have
to take but I didn’t have to take. So I was looking for an extra
My girlfriend was visiting Cornell at the time, and I was showing
her around the Cornell campus, and for some reason—I don’t
remember why—we stopped into the Space Sciences Building, where
I teach now. Where I am now as we have this interview. Down on the
first floor, there was a little bulletin board, and she spotted it.
On the bulletin board—I remember it was blue—a little
three-by-five note card. Just a tiny little sign saying that a professor
named Joe [Joseph] Veverka, who was a member of the science team for
the Viking mission to Mars—this is 1977, and Viking was flying—that
he was going to be teaching a course on the results of the Viking
mission. I thought, “Well, that sounds interesting. I’ll
sign up for that.”
I went to the first day of class, and it was a course exclusively
for graduate students, he said. He didn’t want any undergraduates,
and he said, “Are there any undergraduates here?” One
hand goes up. It was mine. I thought, “Okay, he is going to
throw me out.” He said, “Come see me after class”—a
very stern voice.
I went to go see him after class, and he was about to throw me out,
I can tell. Then what happened was at the critical juncture, a graduate
student from the geology department who knew me pretty well saw what
was happening, came up, and vouched for my studious nature with the
professor. Fortunately, he relented and he said, “Okay, you
can take the class.” So I was allowed into this class almost
Because it was a graduate-level course, we were expected to do some
kind of piece of original research for our term paper. The whole course
grade was based on a single term paper. I had never done that before,
so two or three weeks into the semester, I started to think, “Well,
boy, I better start thinking about my term paper.”
At that time, images from the Viking orbiters were coming down from
Mars daily. Of course, no CD-ROMs, no internet, nothing like that.
They were printed on big rolls of photographic paper and shipped in
big cardboard boxes to the lucky 30 people, or whoever it was, that
were part of the Viking science team.
At Cornell, Joe Veverka, the professor, would get these boxes of pictures,
and then somebody would slice them up and put them in plastic sleeves
and put them into binders. There was this room called the Mars Room
in the physics building here where all these pictures were kept. And
so I thought, “All right, I’ll go and look at some pictures
of Mars, and maybe I’ll get some ideas for my term paper.”
The professor gave me a key to the Mars Room, and I remember this
so vividly. I walked in there. It was just metal shelves, and linoleum
floor, and harsh fluorescent lights overhead, and boxes of photos,
and that sort of thing. I just pulled some of the binders off the
shelves and figured I would spend 15 or 20 minutes flipping through
the pictures and see if I could come up with an idea for a term paper.
I was in that room for four hours, and I walked out of there knowing
exactly what I wanted to do with the rest of my life. It was an absolutely
transformational moment for me, because this was the blank canvas
I had been looking for. I didn’t understand what I was seeing
in those pictures, but the beauty of it was that nobody did.
This was stuff that maybe a hundred people on Earth had even seen,
and it was an unknown world, and it was fascinating to me. It was
just captivating. And that was it. The term paper that I wrote became
the first scientific paper I ever published, and that’s all
I’ve wanted to do ever since, is explore the planets.
I finished up my undergraduate career at Cornell, and then Carl [E.]
Sagan [astronomer and science communicator] invited me to be his graduate
student for the Voyager mission, which was what was happening in ’79,
’80, ’81, the timeframe that I was going to be in graduate
I had applied to, I think, five different graduate schools, all with
strong programs in planetary geoscience. Cornell was one of them.
I really had no intention of going to Cornell because I had been there
as an undergraduate, but I applied for completeness. But Carl was
a member of the science team for Voyager, and nobody at any of the
other schools that I applied to was, and Voyager was the big thing
that was going to be happening when I was in grad [graduate] school.
I accepted his invitation, and then Joe Veverka—the very same
professor who had taught that course that I managed to talk my way
into—ultimately also became a member of the Voyager science
team. So Joe was actually my advisor when I was in grad school in
’79, ’80, ’81.
That’s when Carl was making his Cosmos [A Personal Voyage] television
series, so he wasn’t around much. He was the one who opened
the door to Voyager for me, but Joe was kind enough to take me on
as his graduate student for Voyager. So I was a grad student on the
Voyager project, and that was just an incredible experience.
How did Carl Sagan become interested in you?
You know, I never figured that out. I never actually figured that
out. By this time, I was spending all my time over in the Space Sciences
Building. Probably he just read my application or something. I had
a mailbox in the Space Sciences Building, and there was a note in
it one day that, “Professor Sagan would like to see you.”
Didn’t say why. I had never met the guy. I walked in, and he
sits me down and said, “Hey, how’d you like to be my grad
student for Voyager?” My little heart starts going thump, thump,
thump, thump, thump. Then I said, “Okay, I will think about
I went out of his office, went straight down the hall to Joe Veverka’s
office, walked into Joe’s office, and said, “Joe, Carl
has asked me to be his grad student for Voyager.” This is before
Joe was on the Voyager science team. I said, “Carl has asked
me to be his grad student for Voyager. I’d like to do it because
I want to work on Voyager, so I want to come to Cornell for grad school,
but I want you to be my advisor because I know Carl’s not going
to be around much.” He said, “Okay.” I don’t
know what he was thinking, but he said okay.
That was that. Then Joe eventually got added to the Voyager team too,
so both of them were on the team when we actually did Voyager.
Talk about that for a minute, being a part of that imaging science
team and what you were doing.
My god. That was the most astonishing experience, in so many ways.
It was the one mission that was really returning exciting new data
when I was at grad school, so it was the place to be. Voyager was
a huge step beyond anything that had come before. The Pioneer 10 and
11 spacecraft had flown through the Jupiter system already at that
point, but they had very limited payloads, and really not much in
the way of camera systems.
There was an enormous amount about the Jupiter system that was unknown,
and almost nothing was known about the moons of Jupiter. To me, Voyager
is still the greatest planetary mission that’s ever flown. The
first good look at four big planets and their moons—Jupiter,
Saturn, Uranus, Neptune. You only get to do something for the first
time once, and that goes to Voyager.
Being able to be there and be part of it was just a life-changing
experience for me in so many ways. Scientifically, because my background
was geology, my interest was the moons. The solid moons, primarily
the big ones—Io, Europa, Ganymede, and Callisto. The Galilean
satellites, as they are called, that were orbiting Jupiter. It was
an astonishing experience.
These are big objects. Two of them are about the size of Mercury,
and the other two are about the size of the Earth’s Moon. I
mean, these are substantial objects. Never been seen before, knew
almost nothing about them, and they went from literally little points
of light that you could sort of barely resolve anything—you
study them in a telescope but that was it—to entire worlds that
you could map and begin to comprehend in a real geoscience sense in
the space of 48 hours. It was absolutely incredible.
Of course, I didn’t sleep for the whole 48 hours. The entire
flyby, I was just riveted by the whole thing. Boy, you talk about
the thing that had always driven me was this sense of exploration,
and this was just an avalanche of new information about these new
worlds. That was an incredible experience in itself.
The other thing was that I had the remarkable good fortunate to get
to work with a few supremely talented and supremely generous scientists
when I worked on Voyager. Of course, there was Joe and Carl. Larry
[Laurence A.] Soderblom—he must have been very young at the
time, he must have been in maybe his mid-30s or late 30s—but
he was the deputy leader of the Voyager imaging team.
Then somebody who just made a huge difference to me in my career was
Gene [Eugene M.] Shoemaker. Gene Shoemaker, U.S. Geological Survey
in Flagstaff [Arizona], and also Caltech [California Institute of
Technology, Pasadena, California]. Gene was one of the scientists
who was involved in Voyager, and I got to work very closely with Gene,
and it was just one of the best experiences.
Let me tell you a Gene Shoemaker story. This is something I will remember
for the rest of my life. I’m a first-year graduate student.
The Voyager spacecraft—it’s probably Voyager 1—is
bearing down on Jupiter, ’79, so I would have just turned 23
years old. I’m at the [NASA] Jet Propulsion Laboratory [Pasadena,
California] for maybe the second time in my life, and things are really
starting to heat up. Images are coming down, stuff is happening. We
are a few days out from the close flyby.
Now, the Voyager spacecraft didn’t carry fancy solid-state data
recorders like spacecraft today do. They had tape recorders—physical
reels of tape that they recorded data on—and the tape recorder
had a limited amount of space on it. A problem came up. This is late
at night. The only two people who were around were me and Gene. We
are in the imaging area of JPL, and a problem had come up at one of
the Deep Space Network tracking stations where you receive data from
Data had come down and it had not been properly received, and so there
were images of some of the moons of Jupiter—these are early
images at low resolution—that hadn’t made it down from
Jupiter. They were still recorded on the tape recorder, but they hadn’t
come down. But we also had a set of commands that were about to go
up to the spacecraft to instruct it to take some other pictures that
were going to get written onto that portion of the tape recorder.
We could decide—do we send those commands up, or do we keep
them on the ground?
What it amounted to was we had to choose. We could have the pictures
that had been taken already and not get the new ones, or we could
have the new ones, which would then overwrite the pictures that we
had taken already. But there was no way to get them both. A choice
had to be made. That choice was based on science, because these images
were taken from different angles, different solar illumination, different
rotation of the moons. “Which is more important? Which one had
the most science?” Something’s got to go.
The engineers want to let the scientists make this decision, so they
came in, and there is the great Gene Shoemaker plus this kid. They
go and say, “Dr. Shoemaker, we need your guidance on something.”
They explained the situation, and “We’d like you to come
over, and we’ll show you exactly what images are at risk, which
images you can choose between. Could you please come and give us some
guidance on this?”
And Gene, bless his heart, turns to me and said, “Steve, could
you come help me out with this? I could use some help on this.”
And so I went along with him. I had been looking at these images,
I had been thinking about them, and if you gave me the chance, I might
be able to offer an opinion. He didn’t need to do that. It was
the first time that a real scientific professional who I deeply appreciated
treated me as a peer. I got a lot of that on Voyager, and that just
meant so, so much to me.
To this day—gosh, what is it—40 years later now. Forty
years later, one of the most satisfying things to me about doing the
Mars rover missions, Spirit and Opportunity in particular, is that
I get the opportunity to do the same sort of thing for very young
students who are interested in this field. I was never, ever able,
of course, to repay Gene and all the other Voyager scientists for
what they did for me when I was that young, but I feel like now, 40
years later, with the rovers having worked out the way they did and
having had so much student involvement in the mission, I finally just
feel like I’ve kind of paid off that debt.
It’s always nice when—in any field—you are treated
as a peer instead of a student. So yes, that’s pretty amazing.
It meant a lot to me.
You worked on the Voyager all through your PhD?
Yes. I worked on Voyager all through my PhD. I wrote my PhD thesis
about Ganymede and Callisto, which are the two big, icy moons of Jupiter.
Boy, talk about being in the right place at the right time.
Simplemindedly, you can divide the solid bodies in the solar system
down into two types. There are the ones that are made of rock and
metal, and then there are the ones that are made of ice and rock.
Ganymede and Callisto were the first two icy ones anybody had ever
seen, ever. I chose those for my PhD thesis, and I got to write the
first papers about all of those, coauthored with other prominent scientists,
Gene among them. I was just there at exactly the right place at the
Since this is oral history, let me tell you an embarrassing story
about myself. I’m really embarrassed by this, but what the heck.
We’ll put it out there. This is how I chose my thesis topic.
When we got the first data from Voyager—the Voyager 1 and Voyager
2 Jupiter flybys—there were some fabulous discoveries. These
volcanoes erupting on Io, these fractures on Europa suggesting that
maybe there was an ocean of liquid water underneath the ice, just
You get this big team of scientists, and everybody is going to write
papers, and you don’t want people stepping on each other’s
toes. You want to have some sense of organization—who is doing
what, who is writing papers about what topic, and so forth. So Larry
Soderblom, who was the leader of the geoscience part of the Voyager
mission team, he gets all the geo types together. The high and mighty
professors—the Gene Shoemakers and Joe Veverkas—all the
way down to the lowly grad students.
He says, “Okay, guys. I’m going to put an envelope on
my door, and what I want you to do is take a piece of paper, write
your name on it and which moon you want to work on. Pick one moon
that you want to work on most, and write your name on it, and put
the slip of paper in the envelope. Then, once I’ve accumulated
enough, I’ll go through them, and we’ll sort of figure
out how we are going to divide it up.”
This is the embarrassing part—I didn’t put my name in
initially. I waited and waited until people put their names in. Then
one evening, when there was nobody around, I went and I pulled out
the pieces of paper. I go through them, and it’s like “Io,”
“Io,” “Io,” “Europa,” “Europa,”
“Io,” “Europa,” “Europa,” “Europa,”
“Io,” “Io,” “Europa,” “Europa,”
and then “Ganymede, Gene Shoemaker.” I realized if I picked
Ganymede for my thesis topic, maybe I can work with Gene. That was
how I picked it.
I did, and I picked Ganymede as the focus for my PhD thesis. I figure
all the really sexy, jazzy science is the Europa and Io stuff. There
are a lot of people who want to do that. Gene is really fascinated
by Ganymede. “If I work on Ganymede, I can work with Gene.”
And I did. I spent a summer in Flagstaff, Arizona, working with Gene
and writing papers together, and it was just a fantastic experience.
But yes, that’s how I picked my thesis topic.
Actually, it sounds pretty smart to me.
Yes. Well, anyway, a little bit underhanded, but it worked out well
in the end.
What happened next was also very tightly tied to Voyager as well.
Of course, the big discovery on the moons of Jupiter from the Voyager
1 flyby was the volcanoes on Io. Io—nobody had a clue what was
going on. Io turned out to be the most volcanically active body in
the solar system, with six or seven volcanoes spewing sulfur compounds
a couple of hundred kilometers out into space as we were flying by
the moon. It was incredible.
The story there, there was a very interesting story. There was a group
of scientists—one of them at UC [University of California] Santa
Barbara named Stan [Stanton J.] Peale, and then Ray [T.] Reynolds
and Pat [Patrick] Cassen at NASA Ames [Research Center, Moffett Field,
California]—all of them theoreticians. Some years before, they
had developed a theory, a mathematical formulation, of how tidal heating
works. The idea that when tides affect a solid body and sort of flex
it back and forth, it can be heated.
They had developed all the mathematical theory behind tidal heating,
and done all the calculations. They were interested in how much tidal
heating there would be on the Moon, on the Earth’s Moon, which
is in a somewhat elliptical orbit, and so it experiences tides. They
did all the math, and they did all the physics, and they worked it
all out. And it turns out it was, like, 5 degrees or something. They
wrote up the paper and nobody paid much attention to it, and that
Then some years later, Voyager is bearing down on Jupiter, and it’s
going to take pictures of the moons of Jupiter. One of them—I’m
not sure who it was—one of the three of them got the idea. “Just
for the heck of it, let’s just dust off our old tidal heating
equations and try applying them to the moons of Jupiter, and just
see if anything interesting pops out before Voyager gets there.”
They ran the calculation for Io, and they were astonished. The calculation
said that the thing should basically melt. That the tidal heating
would be so intense and so violent that this should be the most volcanically
active body in the solar system. “Okay, we got it wrong. We
have got to go back and check our calculations.” They go back
and they check it, and they check it, and they check it, and that’s
what the numbers say.
They dashed off a paper to Science [academic journal]. They wrote
it in, I think, just a few days, blasted it off to Science, got it
reviewed. It was published in Science one week before the flyby, all
right? This is pre-internet, so word doesn’t travel all that
fast. Unless you go to your library or you go to your mailbox and
you pick up the latest issue of Science, you are not going to see
Meanwhile, the entire Voyager science team, we are so focused on getting
ready for the flyby nobody is reading journal articles. We fly by
Io, there is the whole story of how the volcanoes were discovered;
it was fantastic. And sure enough, Io is the most volcanically active
body in the solar system.
Then somehow we heard about this paper, and we went and read it. I
was just blown away. It was just such a gutsy thing to do to trust
your calculation to make this outlandish prediction when you have
got a very good chance of being proven wrong in a week. I was just
blown away by that.
Now, one thing that I learned—one of the things that I learned
through my association with Gene Shoemaker, with Larry Soderblom,
with Carl Sagan, with Joe Veverka on Voyager—was that when you
surround yourself with really smart people, good things can happen
to you. I was so impressed by these guys that I decided, okay, post-doc
[doctoral fellowship], I want to go work with these guys.
And so my post-doc was at NASA Ames, and I had Joe Veverka write me
a letter of recommendation. In fact, I don’t think it was even
a letter. I think he actually called up Ray Reynolds or Pat Cassen
and talked to them, and that’s how I ended up working for NASA.
Those guys just impressed me so much, I just realized that, hey, if
I go and work with those guys, good things are going to happen, and
After I finished my PhD in 1981, I went out to NASA Ames. I was a
post-doc there for two years, and then got hired on, and I was civil
service for three years.
What were you working on during that time?
Everything under the sun. It was great. When you are in grad school,
your job is to get out of grad school, and the path out of grad school,
it goes through the thesis. You have got to get the thesis done, and
the thesis can’t be just a complete hodgepodge of different
topics, no matter how entertaining they might be. You need to bear
down and get a substantive piece of work on one topic done. That’s
what I did when I was in grad school, and I just focused on Ganymede
and Callisto, and that was it.
I got to Ames, and the shackles were off. I could do whatever I wanted.
So I was doing Mars, I was doing moons of Jupiter, I was doing moons
of Saturn, I was doing comets, I was doing studies for future planetary
missions, I was doing theoretical calculations, geologic mapping—I
was doing just everything all at once. I just exploded in a whole
bunch of different directions scientifically, and it was great.
When you first get out of grad school, those early first few years—you
finished your PhD, so you have your entry ticket. You are now a real
PhD scientist. But it’s before people start asking you to serve
on committees and people start asking you to review papers, and people
start asking you to do this, that, and the other thing. It’s
a time of enormous potential and freedom, and I recognized that. I
realized it at the time that this was a chance for me to really get
a lot of stuff done. And I did, and it was a very exciting time. I
loved being at Ames. I just loved it there, it was fantastic.
But you didn’t stay.
Well, yes. Here is what happened there. I was very happy at Ames.
I really liked being at Ames, I liked working for NASA. The only downside
to it, really, was that it’s right in the heart of Silicon Valley
[Santa Clara Valley, California], and trying to live in that real-estate
market on a government salary was tough. I was married, didn’t
have any kids yet, but the kids were definitely on the horizon.
I wanted to stay at Ames, I liked it very much. I sort of had this
vague long-term plan that I’d stay at Ames maybe 10 years, and
then, I don’t know, convince the University of Colorado that
it couldn’t live without me. Because they are in Boulder, Colorado,
and there’s lots of mountains, right? That was kind of this
vague, long-term concept.
What happened was one day I got a call from Cornell, and they had
a faculty job open and wanted to know if I was interested. I said
no. I had been at Cornell as an undergraduate, I had been there as
a graduate student. I had only been away for about four or five years
at this point, and, I don’t know, going back just didn’t
seem like the right thing to do from a career perspective. Things
were going great at Ames. I really didn’t want to leave, so
I said, “No, I am not interested in the job. Thanks for contacting
I went home that evening and told my wife. My wife was born and raised
in Ithaca, New York. Her family is there. She said, “You did
what?” So the next morning, I called back. I called Cornell
again and said, “I think I might be interested.” I went
and visited, and it went well, and they offered me the job. I sort
of oscillated over it for a while. I wasn’t sure really whether
I wanted to do it or not, because there were a lot of pluses to staying
But in the end, the appeal of Ithaca as a place to raise a family—small
town, inexpensive real estate, terrific schools, low crime rate. Buy
a nice house out in the countryside on five acres of land—you
can’t do that in Silicon Valley. And so that’s what we
did. Came back and moved back to Ithaca in 1986, and I’ve been
here ever since. Raised two daughters, and they both loved it. In
hindsight, as much as I enjoyed Ames, and as much as I still miss
Ames, it was the right decision.
Did you know when you went back that you were going to continue to
have this association with NASA through all these years?
Actually, that’s a really good question. When you make the choice
to leave NASA—I was as civil servant working for NASA. I had
a NASA badge and all that. When you make that decision, you sever
some of your ties. I was no longer going to be a NASA employee. I
still wanted to work on NASA missions, but what that meant was that
if I wanted to be associated with NASA missions going forward, I was
going to have to write proposals, and I was going to have to, through
competitive peer review, get associated with these various missions.
Now, I had, at that point, already had a little success with that.
There was a mission called Mars Observer—a very ill-fated mission—that
I guess the science team for Mars Observer was selected, I think,
in 1985. This is when I was at Ames. I had written a proposal to become
a member of the science team for the gamma ray spectrometer on that
mission. The proposal was selected, and so I became a member of the
science team for that.
So I was already having a little bit of success getting associated
with NASA missions, and when I moved from Ames to Cornell, my affiliation
with the Mars Observer missions moved with me. I remained a part of
that science team, of course, so it was just a different way of getting
myself associated with NASA.
The other thing that happened around this time, though—this
was when the notion of the Mars rovers was first born. I wouldn’t
say it was prompted by the move to Cornell, but it coincided with
it pretty closely. In the 10 or so years between when I first walked
into the Mars Room and decided I wanted to be a planetary scientist
to when I finished my PhD and moved to Cornell and was a professor,
I had done a lot of science that was theoretical in nature. A lot
of geophysical calculations, that sort of thing, and I did a lot of
science that was analysis of data, primarily imaging data from spacecraft.
And I was beginning to find it frustrating, I was beginning to find
I was doing all this research on Mars, for example. Mars was the place
that most captivated me. I had been sort of sidetracked to the moons
of Jupiter because that was what was happening when I was in grad
school, but it was always Mars that kind of did it for me. And the
reason was that Mars, of all the planets, looked like it was the one
that had the greatest potential to have had habitable conditions at
the surface. I just found that fascinating, and always had.
I remember I would do all this science with the Viking images and
theoretical calculations of conditions on the Martian surface, and
the problem was it was so hard to get to anything like a definitive
answer. You would do these theoretical calculations and you’d
come up with an answer, but then you’d make a few reasonable
tweaks to some of your parameters and you’d get a different
answer. You would look at these pictures of things from orbit, and
you would look at it and you would say, “Well, it could be this.
But it could be this. Or it could be this.”
The thing was—remember I had years of training going back to
the Juneau Icefield when I was 18 years old of doing field geology.
Boots, a hammer, working with the rocks close up. I’m looking
at these things from orbit and I’m trying to figure out what
it means, and I knew—I just knew—that if you could just
give me five minutes with my boots and a rock hammer on the ground
on Mars, I could answer the question. You get down and you look at
the rocks up close, and there are things that you can see—if
you know what you are looking for—that will give you definitive
answers that you just can’t get from orbit.
That frustration with working with orbital data, working with remote
sensing data, and my desire to really, really, really dig into this
issue of the habitability of Mars, those two things together were
what led me to start thinking about Mars rovers. I first really began
the quest to get some serious geological instrumentation onto the
surface of Mars in 1987, which was like a year after I showed up at
Did you have any involvement with [Mars] Pathfinder?
No, I didn’t. I did not. I tried, but I failed. We are getting
into the stuff that I talk about in my book now [Roving Mars: Spirit,
Opportunity, and the Exploration of the Red Planet], but yes, the
Mars Pathfinder mission, they were looking for a camera on that lander.
That was the first Mars surface science proposal I submitted, the
first of four.
After I had been at Cornell for a few years, I took my first sabbatic
leave at an aerospace company. I left Cornell for a year and went
out to Boulder, Colorado, and I worked at Ball Aerospace [& Technologies
Corporation]. I was there for quite some time, and worked to develop
a camera system, which we proposed for Mars Pathfinder.
The proposal was unsuccessful. We made an egregious error in writing
our proposal. The camera that we proposed had to fit into a specific
three-dimensional volume on the spacecraft. There was a diagram that
NASA provided that showed what the volume was, and we looked at that
volume, and we designed a camera that would fit nicely into it. What
they had done was they had printed the diagram sideways on the page—they
had rotated it 90 degrees from the actual orientation on the spacecraft—and
we misinterpreted the diagram.
Yes, we misinterpreted the diagram. They wanted a camera that was
short and fat, and we proposed one to them that was tall and thin.
Because we misread that diagram, our proposal was basically rejected
out of hand. That was a learning experience, boy. So I was not involved
in Mars Pathfinder. In fact, the day that Pathfinder landed, I was
in a cabin in the Rocky Mountains working hard on the proposal that
eventually became [Mars Exploration Rovers] Spirit and Opportunity.
That camera system, just as an aside, did it ever get used on anything
The only thing that actually survived was the name. It was a true
panoramic camera. It had a 3,000-pixel detector, just a line array
that you would rotate very smoothly and precisely to build up this
big, big, big panoramic image all in one sweeping motion. It was a
beautiful camera, and because it was a panoramic camera, we called
The Pancam cameras that we flew on Spirit and Opportunity wound up,
in the end, using a completely different design because of a whole
bunch of engineering and financial constraints that we faced, but
sort of to honor the team that I worked with to develop that first
Pancam camera for Pathfinder, we kept the name. But the name was all
that survived. It was a beautiful camera.
We can talk about the Mars work too, but you were also busy doing
other proposals, or working as investigator on other things, during
the late ’80s.
Yes, yes. The thing that I really wanted to focus on, of course, was
Mars and Mars rovers. I spent 10 years, and there were four proposals
before we finally got selected on the fourth try.
But there were other things going on in that same timeframe too, and
those proposals were all successful. I proposed to be on the science
team for the Magellan mission, on the radar team for the Magellan
mission to Venus, and was successful as part of that. I was on the
gamma ray and x-ray spectrometer team for the Near Earth Asteroid
Rendezvous mission, so that was a big thing for me.
And then even though Mars Observer was unsuccessful, the gamma ray
spectrometer that I was part of eventually did fly on the Mars Odyssey
mission, and so I was involved in that as well. There were a number
of missions that were happening in that timeframe, in the early to
mid-’90s, that I had proposed to be part of the team. I proposed
to be on and I was selected for the imaging team for the Cassini mission
to Saturn. So there were a bunch of things that I was working in the
same general timeframe.
Do you want to talk about or discuss any of those, and what your impressions
were, or maybe some of your favorite memories in some of those?
Sure, sure. Magellan, for example, that was a fantastic experience.
Magellan, of course, was a radar mapper. There had been a few missions
to Venus previously. The U.S. mission, Pioneer Venus, had had an ice
altimeter, and it produced kind of a low-resolution topographic map
of the planet.
Then there had been Soviet missions which had done some radar mapping
on portions of the planet, and put—successfully—several
landers down on the planet’s surface. But the objective for
Magellan was to produce a high-resolution imaging radar map of the
entire planet. It’s a big planet, it’s the size of Earth.
The spacecraft got there, and the way Magellan worked was it would
lay down these little spaghetti-like strips of radar coverage. It
would come in over the pole, it would lay down a strip—I’m
probably going to get the numbers wrong, but it was about 25 kilometers
long, I think, and thousands and thousands and thousands of kilometers
long from the north pole down towards the south pole. You would get
this little narrow strip.
Then the spacecraft was in an elliptical orbit, so the orbit would
carry it farther away from the planet. It would turn, it would send
that radar image—this little noodle of data—down to Earth.
Meanwhile, the planet’s rotating. Venus rotates very slowly.
The planet’s rotating underneath the spacecraft. The spacecraft
comes in, and the orbit was sized and timed just so that when the
spacecraft came in over the pole again, the planet would have rotated
20-some odd kilometers, and so you would lay down another strip right
next to it. And then another, and then another, and then another.
It was fascinating to me because it was like the exact opposite of
Voyager. Voyager, you would get this distant view, and then, wham,
you would get the whole moon of Jupiter just all at once. Whereas
with Magellan, it was this very slow reveal. It was like a crack in
the door opening very slowly, and this radar strip would get slowly—every
day—wider, and wider, and wider, and wider, until a whole planet
eventually came into view. That was fantastic.
That was a wonderful experience also. By that time, I was a PhD scientist.
I was on the faculty at Cornell, so it wasn’t a grad student
kind of experience. But still, I was working for the most part with
scientists who were more senior than me, who knew more about Venus
than me, so it was a chance to learn a lot. It was a chance to work
with radar data, which is in many respects very different from camera
data, imaging data. I learned a great deal, and that was a terrific
The Near Earth Asteroid Rendezvous mission – that was another
great one. That was more gamma ray and x-ray spectroscopy, like I
had done at Mars. This was on the asteroid Eros, and that was a whole
new thing. That was the first time anybody had ever orbited an object
like that, and so we had to learn how to fly a spacecraft around that
kind of object. How to do mapping when you have got this irregular,
complicated-shaped spinning object underneath you.
Each one of them was a new challenge, and each one of them, you are
seeing things that nobody had ever seen before. That combination of
technical challenge and geographic exploration, seeing stuff that
nobody had ever seen before, just appealed to me greatly. I don’t
know, that impulse to get there first has always been something that
has driven me. In some ways, it’s a very selfish motive, right?
“I want to see it first.”
But that’s always been a big, big part of what I’ve loved
about what NASA does, what I’ve loved about being involved in
these missions, is the chance to get a first look at something that
no human eyes have ever seen before. I have always found that very
Has it ever been compelling enough for you to want to see it first
yourself, as an astronaut?
Yes. The problem is that in the timeframe when I could have flown
as an astronaut, it was all low-Earth orbit. There was no chance to
actually go there, and we weren’t going to the Moon—I
was too late for the Moon, too early for Mars. In order to do the
kind of exploration that I wanted to do, I had to give up on the notion
of going myself, and focus instead on building robotic systems that
would serve as a proxy.
What I have done to soften that blow is, throughout the years that
I have been doing this ever since grad school and before—once
I made the decision to conduct my career with robotic exploration—is
to do my exploring sitting at a desk in front of a computer. I did
also at the same time make a decision to continue to be engaged very
much, whenever I get the chance, in real boots-on-the-ground exploration
I have been going on scientific expeditions, doing field research,
of many, many sorts—most of it NASA-related in one fashion or
another—for many years. In the Arctic, in the Antarctic, deep
ocean. I’ve done a whole bunch of that just so it provides me
a way of scratching that itch. In fact, as we are speaking now, four
days ago, I just got back from a week of NASA-funded fieldwork in
some caves in Idaho.
So, yes. I’ve done, like I said, Arctic, Antarctic, a lot of
underwater stuff, caves now. It provides me with a way of satisfying
that selfish need to go do it myself.
I do want to talk about the NEEMO [NASA Extreme Environment Mission
Operations] experience and some of those other experiences.
Oh, yes, yes. NEEMO is a great example.
Yes. We can get to those, but just out of curiosity, what were you
looking for in caves in Idaho?
Okay, so this is an interesting problem. It has to do with the issue
of the habitability of Mars. Mars has a very, very challenging environment
at its surface. At the surface of Mars, there is a very intense radiation
environment. Not just ultraviolet, but also cosmic rays that can penetrate
significant depths into soil and rock. Very damaging for life. Enormous
daily temperature swings. The temperature difference between daytime
and nighttime is 100 degrees Celsius.
So the Martian surface environment is very dangerous and unstable,
whereas down in a cave—thermally stable, completely shielded
from cosmic rays. It’s a much, much more favorable environment,
in some respects, than the surface environment. Now, why would you
expect caves on Mars? Mars is covered with basaltic volcanism, and
basaltic volcanism produces what are called lava tubes. We know that
there are these lava tubes on Mars, and then the lava tubes are caves.
We are working in a place called Craters of the Moon [National Monument
and Preserve] in Idaho where there are large basaltic lava fields
that were laid down 2,000, 3,000, 4,000, 5,000, 10,000 years ago,
and there are lots and lots of these lava tubes, these lava caves.
On Mars in lava caves today, it’s very, very cold, and probably
not all that suitable an environment for life today.
However, if you go far enough back in time, to go back to Mars 3 billion,
3.2 billion, 3.5 billion years ago, those lava caves could have been
some of the best environments for Martian life to be able to persist
and survive. Because it’s shielded from the cosmic rays, it’s
more thermally stable, and so forth.
Now, the question then becomes what do you do? What do you go and
look for? If you want to look for evidence of former life in Martian
caves, what do you look for? It turns out in these caves in Idaho,
there are some fascinating mineral deposits. These are minerals like
sulfates that are precipitated from very small amounts of liquid water.
A little bit of liquid water will percolate through the ground, and
then it will evaporate onto the walls of these caves or on the floor
of these caves, and it’ll form these dense white mineral deposits.
It turns out there are microbes that are living in the caves, and
they become trapped in these mineral deposits like bugs in amber.
Trapped inside of them.
The team that I was working with, what we were doing is using sterile
procedures—so we are in caves and wearing hard hats and kneepads,
but we’ve also got surgical gloves and surgical masks and sterile
tools—and what we are doing was getting samples of these mineral
deposits. Then the scientists take those back and extract DNA [deoxyribonucleic
acid], amplify it using techniques like polymerase chain reactions
(PCR), sequence it, do genomic determinations of what microbial communities
exist in these things, and help you to understand the ways in which
what you might call biosignatures—the evidence for past life—can
be preserved in those kinds of mineral deposits.
So that if you go to caves on Mars, what kind of mineral deposits
might you want to look for? What kind of stuff might you want to look
for preserved in those minerals that could provide evidence that something
had lived in a cave on Mars billions of years ago? It’s kind
of laying that groundwork.
It’s not very different conceptually from work that I did in
Antarctica back in the mid-’80s, when I knew that someday I
wanted to try to send a rover to Mars and look for what kinds of processes
might have gone on in Martian lakes. So we were studying Antarctic
lakes as a way of helping us to prepare for the kinds of tools that
we might want to send to ancient dry lakebeds on Mars someday.
It can be valuable to go to analogous terrestrial environments to
learn about what you might find in the Martian environment, to prepare
you for the exploration that you want to do maybe a few decades down
Do you think that exploration, as far as getting in these lava tubes
on Mars, would that be robotic or human?
It’s going to be tough either way. I’ll tell you one thing
for sure, it’s not going to be solar-powered rovers. It’s
My guess is that initially, it would probably be robotic systems.
For a place like Mars, you usually want to send robots first, and
then humans later. That’s what we’re doing now. I don’t
know, I don’t know. The first thing you have got to ask is “What
are we looking for?”, “What are the scientific questions
we are going after?” And then you say, “Okay, what’s
the best way to do it?” We are really just getting started on
this stuff. You could do it either way, or both.
But it was fun. I’m not doing the science, really. I’m
not extracting the DNA, I’m not doing the PCR. I’m a field
assistant. I’m out there with scientists who are in their 20s
and 30s, like I was when I first started doing this stuff, and I am
a field assistant. I have got decades of experience doing fieldwork
in all kinds of settings. I carry rock samples, I help navigate us
to the mouth of the cave. I go in and I’ll scribble down notes
that are dictated to me by the real scientists doing the real work.
It’s wonderful fun for me. I’m 61 years old, I’m
still physically fit enough that I can do this kind of stuff and enjoy
it. I don’t know how much longer that’s going to last,
but I can now. It’s just wonderful fun working with these just
talented, energetic 30, 35-years-younger-than-me scientists, all full
of ideas, and just go out there and help. Just go out there as their
field assistant. I get to stretch my legs and have fun, and they get
some data. I love it.
Just curious, when you started working and doing research for NASA,
it was an interesting time. There was a lot going on as far as near-Earth
orbit, as far as the [Space] Shuttle, and then working on ISS [International
Space Station]. But there were also all these other missions in your
field, going on to other planets. I would imagine there was a lot
of excitement because, as you said, Voyager, all these things were
just beginning. Do you see that excitement now in these younger people
that you are working with?
Oh, more so. More so. Much more today than back then. We look back
on the early ’80s, and let’s talk about planetary missions.
Name them, name the planetary missions that flew in the 1980s. It
was almost nothing. There were no Mars missions going, Viking was
over. Voyager kept flying, but it was launched in ’77.
Magellan didn’t come along until the end of the decade. Galileo
was supposed to happen, but then it went through launch delay after
launch delay, and then it took forever to get to Jupiter because of
the trajectory that they had to fly. It was actually a time of very,
very little planetary [science] activity.
Now, as you say, there were lots of other exciting things that were
going on at the time. The Shuttle was really a going concern, the
Hubble Space Telescope was getting designed, and then eventually launched.
There were plenty of exciting things happening at NASA at that timeframe,
but it was a time of a lull in some respects in the planetary program.
Now, counterbalancing that is the fact that the missions that were
flying were absolutely groundbreaking. Voyager, as I said, was the
first good look at four complete planetary systems. Magellan was the
first really good, comprehensive look at Venus. That’s not to
denigrate the Venus missions that had come before, but Magellan was
a huge leap over anything that happened previously. The missions that
were happening were really groundbreaking, and so you look back on
them and they—and rightly so—are considered historic.
But it was a time of limited activity, whereas today, there are so
many missions flying. You go to a lunar and planetary science conference
and it’s just swarming with young scientists—way, way,
way more than there were back when I was coming up. I think today
is a tremendously exciting time, and in some respects more exciting
than it was back then.
Maybe because we have seen some of the results of those earlier missions
Yes. And you build on them. I think the other thing is that NASA just
has a more vibrant planetary program now. Back in those days, we would
fly a very small number of very big missions, the so-called flagship
missions, and there weren’t the smaller missions. You didn’t
have Discovery missions, you didn’t have New Frontiers missions.
Smaller, PI [principal investigator]-led things just simply didn’t
exist. There is a more steady stream of new discoveries and new data
today than there was back then.
It seems like for humans, there has always been this interest in Mars,
and for a lot of reasons. I am sure scientific reasons, and some you
mentioned. Each [presidential] administration wants to put their stamp
on NASA and science—some more than others. The first President
[George H. W.] Bush made his statement about going back to the Moon
and onto Mars, as his son [President George W. Bush] did later. Is
Mars one of the things that drives that interest, do you think, especially
with the generation now?
Sure, of course. Yes, yes. Yes, absolutely. The thing about Mars is
Mars has two characteristics that make it unique. One is that it’s
one of the few places in the solar system where habitable environments
might exist today, and did exist in the past. There aren’t a
lot of those.
The other is that it is one of the very few places—really, the
only place—where humans can go to those potentially habitable
environments, where humans can go to environments that were once habitable.
That issue of accessibility for humans and habitability for potential
former life forms, those uniquely converge at Mars.
Europa’s fantastic, fabulous. There could be an ocean on there,
on Europa, but you are not going to put humans down into that ocean
anytime soon. Same with Enceladus. Whereas Mars, accessible. That
combination of habitability and accessibility makes Mars unique.
As you have been working through the years on proposals, in those
early times—and as I mentioned, the Presidential administrations
come and go, and the budget also comes and goes, especially for exploration.
Maybe just talk for a minute about competing for NASA dollars.
Oh, boy. Yes, yes. The competitive process—incredibly valuable,
incredibly necessary, incredibly unpleasant. It has to happen. The
ratio of pretty good ideas to actual flight opportunities is enormous.
There are so many pretty good ideas out there and so few opportunities
for flight that you need some process by which the people with the
ideas can demonstrate convincingly that their idea is worth hundreds
of millions of taxpayer dollars, and is better than this idea, and
that idea, and the other idea that somebody else came up with. So
how do you make that decision? The way that it’s done is through
competitive peer review, and it’s a very Darwinian process.
A lot of failures, not too many successes. Far more unsuccessful proposals
than successful proposals.
The things that make it unpleasant—first of all, you usually
lose. Most proposals are unsuccessful, so you put years of your life
into these things, and most of the time you come up with nothing.
It pits friend against friend, colleague against colleague. Now, we’re
professionals. We can get along and compete with one another. But
that issue of competing for your professional success against your
friends and your peers, it’s not an entirely comfortable experience.
You all want to be friends once the competition is over, but it kind
of sucks some of the fun out of it when you are trying to beat your
But it forces you to do good work. I am sitting in my office in Ithaca,
and I have a stack here of some of the past proposals that I wrote
for doing rover stuff on Mars that were unsuccessful. I spent 10 years
writing unsuccessful proposals for NASA before we were finally selected
on the fourth try.
It was no fun, but I can look at those failed proposals today and
I see the flaws. They were the best that I could do at the time. I
put together the best team that I could, we’d work as hard as
we could, we would do the best work that we could, but I can see the
flaws, and I can see why, yes, they probably didn’t deserve
to be selected, no matter how I might have felt about them at the
That competitive pressure forces you to make tough decisions. It forces
you to get better at what you do. It forces you to sharpen your thinking
and improve your ideas, and improve your designs, and come forward
with something that actually has some reasonable probability of working.
It would be incorrect for anyone to assert that the best proposals
always win, because the proposal evaluation process—the process
of reading all of these proposals and deciding among them—is
as imperfect as the proposal writing process. It’s done by humans,
people make mistakes, people make misjudgments.
So the whole thing—proposal writing, proposal reviewing, proposal
selection—every aspect of it is imperfect, but it’s good
enough that if you look at the missions that have flown, it’s
worked out pretty darn well.
Well, as you mentioned, you did four before one got accepted.
I’ll tell you, after the first three I was ready to quit. I
was just fed up. I was very close to a career change after that third
Talk about some of the proposals that didn’t succeed, and what
the difference is. I know you learned from the ones that don’t
succeed, but what made the fourth one successful?
Yes, okay. One of them we’ve already talked about. One of them
was the proposal—a camera for Mars Pathfinder, and that was
just a really stupid mistake. Now, even if we hadn’t made that
stupid mistake, it’s not clear that we would have won, because
there were a couple of really solid competitors. But that mistake
The next proposal was an entire scientific payload for the 1998 Mars
lander mission. It was a very nice payload. It included many of the
instruments that ultimately flew on Spirit and Opportunity. We had
three different teams competing against us. The team that won was
selected to do a mission that became known as Mars Polar Lander. When
I got the news that we had not been selected for the ’98 lander
mission, that was a devastating loss because I really thought we had
a good proposal. I really thought it was strong. I wanted to win it
very, very badly.
I remember I got the call from NASA Headquarters [Washington, DC].
I was in Paris [France] at the time. After getting that phone call,
I couldn’t sleep. I spent the whole night walking around through
the streets of Paris in the rain just feeling depressed. That mission
became Mars Polar Lander, which of course was a mission that ultimately
failed because the lander crashed on the Martian surface. As bitter
a disappointment as that loss was, it may have been one of the best
things that ever happened to me.
The next proposal was a Discovery mission proposal, so this is a PI-led
mission to send a small rover about the size of—well, no, not
as big as one of the MER [Mars Exploration] Rovers, but a comparable
set of science objectives. That was not selected either. Then what
did happen was they sort of took that basic concept that we had proposed
and turned it into an opportunity for a rover mission to be launched
in 2001. We proposed a payload for that rover, and that was the one
where we ultimately got selected.
What then happened was the rover got kicked off of that mission and
it became a lander mission, and then the lander mission got canceled
after the ’98 lander failed. Then from the ashes of that arose
Spirit and Opportunity. That’s a whole long, complicated story
that I tell in great detail in my book.
Yes. I’m sure it is complicated.
Yes, but it is kind of interesting, the whole background of that,
and I was talking with [G.] Scott Hubbard this morning.
Oh, okay. Well, Scott knows that story well. He was right in the middle
of it all.
Right. He has also written a book about Mars, so there is a lot of
documented stuff out there. But it’s just interesting, that
whole human element, especially trying to get these things going.
Like you said, you had thought about those rovers early on—
—and if you couldn’t get your own boots on the ground,
then you could get these rovers up there. Was it 2000 that it was
decided that they could go ahead with a rover?
Yes, it was 2000. Summer of 2000.
And then, of course, the story goes that [NASA Administrator] Dan
[Daniel S.] Goldin said, “Well, why not two rovers?”
Oh my god, I think—to this day—that would have to be the
most astonishing phone call of my life.
Well, just talk about that for a bit, if you don’t mind.
Okay. There were two ’98 missions. There was [Mars] Polar Lander
and [Mars] Climate Orbiter, and they both failed. After the failure
of both of those missions, Ed [Edward J.] Weiler, who was now the
[NASA] Associate Administrator for Space Science, kind of wiped the
slate clean in the Mars program and says, “Okay, look. Let’s
just stop, figure out what we did wrong, and then do something different.”
At one point, there were just dozens of different possibilities for
what might fly in 2003. After a very, very chaotic process and winnowing
of them down, it came down to two. It came down to two missions. One
was what eventually became Mars Exploration Rover project, and the
other was what eventually became the Mars [Pathfinder] rover. There
was a surface rover delivered using an airbag system, versus a big
orbiter with lots of instruments hung on.
There was this head-to-head shootout, two days long, at NASA Headquarters
summer of 2000. Each team had basically a day to present their science
and their engineering, and then there was this panel—I think
it was 12 people, something like that—that was to go off and
make a recommendation.
Ultimately, the decision was going to be made by Dan Goldin, the NASA
Administrator. This committee would make a recommendation to Ed Weiler,
Ed would come to his conclusion and would make a recommendation to
Goldin, and Goldin would make a decision. It was going to be one or
the other. It was going to be either the rover mission—this
one rover—or it was going to be the orbiter.
We knew the day that it was going up to Goldin. By the time it went
up to Dan, I had already heard from Scott Hubbard that the recommendation
was going to be for the rover mission. That was the decision that
Weiler had decided on, and so he was going to recommend that to Dan.
I was sitting exactly where I am right now, staring at the same phone—I
had the same phone, right here—waiting for the phone to ring.
I was sitting here and waiting for the phone to ring, and the phone
rang, and I picked it up. I was expecting it to be one of the guys—Scott
Hubbard maybe, or Carl [B.] Pilcher, one of the Mars people from NASA
Headquarters—with the news.
Instead, it’s the entire Mars office. Five, six, seven—I
don’t remember—a half a dozen people all on a speakerphone.
They said to me, “Steve, we have to ask you a question.”
I said, “Okay, what?”
They said, “Can you build two?” And as God as my witness,
the next two words out of my mouth were, “Two what?”
They said, “Two payloads.”
I said, “Why would you want two payloads?” It still wasn’t
They said, “For two rovers.” I just about fell off my
It was brilliant. It was brilliant, because there were some real problems
with what we had proposed. One is it’s risky, and we all knew
it. Landing on Mars is risky. A lot of Mars lander attempts have failed.
This was a dangerous thing to try, and you really improved your chances
if you can fly two.
The other thing was at the time, we knew so little from the missions
we had flown—this is before MRO [Mars Reconnaissance Orbiter],
this is before an enormous amount of data that we now have was in
hand—you didn’t really know the right kind of landing
site to send the rover to. If you have got to pick just one landing
site, you could guess wrong and you come away with nothing. Whereas
if you can send two rovers, send them to two very different sites,
you double your chances of making a good decision about the kind of
site to go to.
It was a brilliant strategic stroke, and he caught us all completely
off guard. Not one of us had even thought about what it would take
to do this. Now, I knew where my payload stood—I knew what the
status was on my instruments, I knew how mature they were—so
my response to the guys at Headquarters was, “Sure I can build
two. Just send money.”
Then off they went. It took a few days to kind of round up the money
to pay for the second rover and all of that, but in the end we flew
two. But I don’t think I have ever received a more surprising
phone call in my life. And it was all Dan, it was all Dan Goldin.
Yes. A lot of things then were “all Dan Goldin.”
Yes. Oh, yes.
I know you have covered a lot of things in the book, I am sure, but
since—when was the book? 2005, 2006?
Something like that, yes.
A lot’s happened since then, including these rovers had a long
life. Talk about that just for a minute, and the experience of one
of them still going strong.
Yes. Anybody tells you they thought the [Opportunity] rover was going
to last this long, they are lying. I can actually prove to you that
we didn’t think they were going to last more than a couple years
Each rover carries what’s called an X-band transponder. It’s
the radio, basically, and it’s the electronics unit within the
vehicle that carries out the communications with Earth. The frequency
on which these transponders receive and transmit is locked in. You
can’t change the channel, the frequency. It’s got a single
We built four of these. We built two flight transponders, and then
we built two flight spares that were identical to the flight units
in case something went wrong. So we had four of them. The flight units
were both fine—we flew them on Spirit and Opportunity—so
now we have these two transponders sitting on the ground after we
Not long after we launched, the Mars Reconnaissance Orbiter project,
which was the mission that had been selected to follows ours and was
going to be an orbiter, came to us and said, “Hey, guys, we
need an X-band transponder. You are not using your flight spares.
These things cost $1 million apiece. Can we have one of your flight
We said, “Sure. We are going to be dead by the time you guys
get to Mars, so go ahead, take one.”
The result was that the Spirit rover and the MRO orbiter for a number
of years communicated to Earth on the same frequency. Operationally,
that was a pain in the neck. We learned how to work around it, but
we never would have given our flight spare transponder to another
Mars mission if we had thought we were going to still be alive 26
months later when that mission arrived. So I can prove to you that
none of us thought it was going to last 26 months.
It’s definitely a lot longer than I’m sure any of you
Yes. It was, and has been, and continues to be. It has caused a lot
of problems, much more money spent on flight operations than anyone,
either us or NASA Headquarters, had ever anticipated. From many of
us who had plans to move onto other things in our careers, it has
kept us working on this one mission for a very long time.
I wouldn’t have it any other way. I’m so thrilled that
the rovers continue to operate. I love it. I love flight operations.
I was doing flight operations for Opportunity yesterday, I’ll
be doing it again tomorrow. Today is a day off in-between, but I do
it on a regular basis, and I absolutely love it.
There is an interesting thing about that. Actually, there are several
interesting things about that. One of them is that when we first did
this and we first proposed it, I seriously underestimated Mars. I
always had this comforting notion that if we managed to launch these
rovers and get them to Mars and operate them, that after a while we
would be able to say, “We did it.” We would be able to
sit back with some satisfaction and say, “We have learned all
that we can learn about these two places on Mars with these two vehicles.
Never happened, never will. You won’t. Mars has turned out to
be so much more complicated, so much more geologically diverse, so
much more interesting than I ever imagined. What I’ve come to
realize is no matter when these things die—I mean, Opportunity
could die tomorrow, it could die 10 years from now—but I guarantee
you that when it dies, there will be some tantalizing thing just beyond
our reach that we’re excited about and didn’t get to.
That’s what happened with Spirit.
Spirit went on for six years, and it was this wonderful place that
was the next thing, and we didn’t make it. We could have discovered
more. The same thing with Opportunity. When Opportunity dies, there
is going to be stuff that we could still do with it. It’s a
good thing, right? You keep discovering new stuff. But it’s
always going to be a source of frustration at the end of the mission.
The other thing is that the open-ended nature of the mission—not
knowing when it’s going to end—has always made the decision-making
process challenging. Every day, we need to sit down, look at where
we are on Mars—the broad strategic picture, the questions we
are seeking to answer. Look at the tactical situation—the rocks
that are in front of us right now, the rocks that are just down the
road, whichever direction we think we want to go.
And we have to decide, “Do we stay or do we go?” Do we
stay here at this place where the science is kind of interesting and
do it thoroughly and carefully, and then move on later? Or do we drive
away right now to this place that’s far away where we think
the science is really good? We face that decision on a daily basis,
and we have been doing that for 13 and a half years.
If you could tell me the day on which the rover will die, and the
way in which it will die, then I could plan. If we knew how long it
was going to last, we could balance the science that we know we can
get here against the science that’s farther away, because we
know how far we can drive before the thing dies. Not knowing when
it’s going to die, you always have to make that decision on
the basis of inadequate information.
We designed for what was supposed to be a 90-day mission. Now, none
of us thought the wheels were going to fall off when the sun came
up on the 91st day. I always thought that we were going to get probably
six months out of them, maybe nine months, maybe-maybe-maybe even
But there were decisions that we made early on in the mission where
we drove away from potential discoveries because we were worried the
mission might be ending in a few months and we wanted to get moving
and find new stuff. If I had it to do over again, I would do it differently.
One of the things that I learned is that if you follow that line of
reasoning, it will make you crazy. It does you no good whatsoever.
You get to a point where you have to make a decision. You make the
decision on the basis of all the information that you have in front
of you at the time, and you move on from it.
Down the road, you learn something new. Down the road, you realize
you have got a longer-lived vehicle than you thought you had? Well
okay, use that information now. You can’t cry about the fact
that you didn’t have that information back then. But that kind
of “When is this going to end?” element of the mission
has been an interesting aspect of the experience.
Why have they lasted? Spirit obviously lasted a lot longer than expected,
and then why is Opportunity still going? Why is it so much resilient
than you had expected?
You asked that question very politely. Some people just say, “You
were really sandbagging us with that 90-day thing, weren’t you?”
There always is this temptation to under-promise and over-perform.
But it comes down to three basic reasons. Number one, we built good
hardware. If you want to accuse us of over-engineering these things,
I will plead guilty as charged. Number one.
Number two, the thing that we thought was most likely to kill the
vehicles was going to be buildup of dust on the solar arrays. The
Mars Pathfinder mission, for example, was the first solar-powered
lander on the surface of Mars, and it saw a steady monotonic accumulation
of dust throughout the mission. More dust, more dust, more dust—that
was it. That was all we knew. So we thought that an accumulation of
dust on the solar arrays was going to be the end. What we encountered
instead was that there would be periodic gusts of wind—we refer
to them as cleaning events—that have cleaned off our solar arrays.
It’s been very different for the two rovers. For Spirit, we
would have long stretches—many, many months—of accumulation
of dust. And then, pow, one huge cleaning event that it was like taking
the vehicle to the carwash, and it would all of a sudden be very,
very clean again. Then it would go on for months and months and months,
and then you’d have another one. We had a handful of those—not
very many—but it completely gave the vehicle a new lease on
For Opportunity, we have never really gotten that rover really dirty.
The wind regime at the Opportunity site is lots and lots and lots
of little wind gusts that are continuously sort of cleaning the vehicle.
Nobody anticipated those. Nobody expected that that was going to happen,
and that has been, in large measure, responsible for the extended
The third thing is we figured out a trick. These rovers were designed
to last for 90 days. They were sent to places on Mars that are—especially
Spirit—in the southern hemisphere. We always knew that in the
wintertime, when the Sun goes low in the northern sky, the conditions
for the rovers were going to get very challenging. Now, what we don’t
have—what we sort of wish we had—is actuators, motors
and gearboxes—that could take the solar arrays and tilt them.
The solar arrays are flat, like the deck of the rover, and they are
just always on the same orientation as the plane of the rover deck.
What you’d like to have, is you’d like to have some motors
that you could use to tilt these things, point them towards the Sun,
point them towards the north when the Sun gets low in the northern
sky, and boost the power output. We don’t have that.
But what we can do is we can drive onto north-facing slopes. While
the missions were designed from the outset to operate on flat terrain,
they’ve lasted so long and we’ve been able to drive them
so far that we have managed to find access to mountains and craters
and hillsides, and places where we can operate the vehicle on substantial
topography for which they were never designed or intended.
So what we have done is in the wintertime, we drive them onto north-facing
slopes. We are doing that right now with Opportunity. As we speak,
Opportunity is in the depths of Martian winter. The Sun is low in
the northern sky, and what we do is we drive from one place where
there is a steep northward slope to another place where there is a
steep northward slope. And we keep the rover always—especially
when it’s at rest—oriented such that the solar arrays
are tilted towards the Sun.
We make what we call “lily pad” maps. What a lily pad
map is, we will use our stereo cameras to generate a topographic map
of the terrain around us. We will calculate which areas have high
northward-facing slopes and are therefore safe for the rover. We then
color-code those maps, so we have a special color that indicates this
is a safe spot. And then maybe 20 meters away, there might be another
safe spot, and then we will drive from one of these safe spots to
the next, to the next. Like a frog hopping from one lily pad to the
next, to the next on a pond. That’s why we call them lily pad
The combination of lily pad driving plus gusts of wind, plus the engineers
at JPL built some kick-ass hardware, that’s why we’re
That’s pretty amazing.
You mentioned that it did create some problems just because the funding
had to continue. Did anyone ever propose the idea, because of funding
and budget cuts, that you just turn them off?
At one point, because of some overruns on the Mars Science Laboratory
Project, there was some talk at NASA Headquarters about shutting off
one of the two Mars Exploration Rovers to pay for part of that overrun.
At one point there was some talk about doing that, but it never happened.
Now, what does happen is every two years, we go through a review process
in which the ongoing planetary missions, MER among them, all have
to get up in front of a very senior review panel, describe the accomplishments
of the past two years, describe the plans for the next two years,
and undergo a fairly rigorous peer review. The results of which NASA
uses to decide do we keep operating these missions, or are we going
to shut something down.
So yes, every two years I have to get up in front of my peers and
justify continued funding of the mission, which, that’s a perfectly
reasonable thing to have to do. We are spending about 12 million bucks
[dollars] a year operating Opportunity, and that’s a big pile
of money. It’s a razor-thin budget for us. We are operating
the vehicles very, very efficiently, but you could do a lot of good
in the world with $12 million. You could do a lot of good at NASA
with $12 million. So yes, we have to get up and justify our continued
operations, and we take that real seriously.
One of the other things that you do and have done throughout this—and
especially after the successful landing—is you have been the
face of the rovers on television. Being interviewed and communicating
with the public. As you mentioned before we started, you have different
people in your audience, and being able to explain scientific things
so that the general population can understand and get excited about
what’s going on is important.
One of your mentors, Carl Sagan, was probably the first to really
be good at that, or to take that on as a mission. Talk about that
for a minute, and what influence he had as far as you being able to
do that, and just where that came from in you to be able to do that.
That is tremendously important. It’s one of the most important
things that we do. I learned many things from Carl Sagan, but that
one has to go very close to the top of the list. Carl understood before
almost anybody else in the space science world how critically important
it was to convey to the public the significance and excitement of
what we do with these planetary missions.
NASA’s not giving our team a billion dollars so we can go off
and have fun, and write our scientific papers and advance our careers.
They are giving us a billion dollars because they have made the judgment
that the discoveries that we will make and the work that we will do
will be of sufficient importance to the people who pay for it that
it’s worthwhile. You do not reap that benefit—you do not
prove your worth—unless you communicate to the people who pay
for it what they are getting for their billion dollars.
So I have always taken that very, very, very seriously. Carl was the
pioneer, and we are all following in his footsteps when it comes to
explaining, especially planetary, science to the public. He was the
master. But not only was he masterful at doing it, he understood its
importance before almost anybody else did.
So yes, I have always taken that very, very seriously for a couple
of reasons. One of them is, as I said, you are trying to help people
to understand the science, and the significance of discoveries and
what they mean, in comprehensible, straightforward language. Not a
lot of scientific mumbo-jumbo, but “Here is what it means, and
this is why I am excited about it, and why I hope you are excited
about it too.”
The other thing, though—and I almost feel that this second item
is the most important—I grew up, as many of us working on MER
did, in the ‘60s and early ‘70s watching Mercury and Gemini
and Apollo on TV, and dreaming of sending spaceships to Mars someday.
We got to do it. Those pioneers, those were our inspiration.
To me, I really believe that one of the most important things—one
of the most significant legacies of missions like MER and others—is
going to be that there is some kid somewhere who is watching the landing,
and watching the first discoveries, and watching us jumping up and
down like we just won the Super Bowl or whatever. Looking at that
and saying to themselves, “That’s really cool, but I bet
I could do better.”
You look at young people in the world today, with all of the flood
of information that they are dealing with from television, and social
media, and all these sources of information flooding at them. They
are making decisions about what to do with their lives. They are making
decisions today that’ll affect the direction that they could
go with their lives later, when they are in high school, when they
are in college, when they are out in the job market.
If you can give young people the sense that science and engineering
are cool, and exciting, and fun, and awesome—that’s a
great thing to do. They are not all going to go work for NASA. They
are not all going to become astronauts or build Mars rovers. But they
are going to follow pathways that are going to make it possible for
them to develop new technologies, new consumer products, new pharmaceuticals,
new things that this society desperately needs.
To the extent that by conveying to the public, especially the young
people, what we are doing and the excitement and fun of it, that’s
one of the absolute most important things that we do. Yes, I’m
very, very proud of the discoveries that we have made on Mars and
the way that we have conveyed them both in the scientific literature
and to the public. But I almost feel like the most important legacy
of some of these—especially a Mars rover mission which is the
one that, frankly, received disproportionate visibility with the public.
When you receive that much visibility, it gives you a special opportunity—but
I think also a special responsibility—to try to use it in ways
that benefit the public, that benefit the country. And we tried really
hard to do that.
I think you succeeded.
Oh, yes. Keep going, the rover’s still driving. We are going
to discover something big tomorrow.
That’s right. We have been going almost a couple of hours, so
it’d probably be a good place to stop for now. But I appreciate
you talking to me today, and finding time in your schedule.
Sure. Glad to do it.
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