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Meet: Nathan Bridges

Planetary Geologist
Jet Propulsion Laboratory, Pasadena, California

nathan bridges photo

My Job

When I started on the Pathfinder project, the spacecraft was on its way to Mars. Showing up at JPL with a lot of knowledge about geology but little insight into actual spaceflight operations, I had a lot of catching up to do. I immediately started attending meetings with the rest of the people on the project. With only a few months to go prior to landing, most of these meetings were very important. Decisions were made on how the spacecraft would be operated, the sequence of engineering and scientific events, and how tasks would be delegated to people on the project. These meetings were very educational, as I learned a lot about the engineering and managerial sides of the project, which, as a scientist, I was not familiar with. Prior to landing, JPL hosted two meetings for all of the Pathfinder scientists. I was the executive secretary for these meetings and took official notes of the proceedings. Another task that I became involved with prior to landing was learning how to write sequences. Sequences are sets of instructional commands sent to the spacecraft. I learned how to write sequences for the main camera on the Pathfinder Lander: The Imager for Mars Pathfinder (IMP).

Between April and the July 4 landing, the entire Pathfinder project conducted three complete simulations of the first five days of the mission. These simulations, called Operational Readiness Tests (ORTs) were long, hard exercises that prepared us for the real thing. Most of us, including me, had really strange schedules during these tests. Because mission operations were governed by the length of Mars' day, which is 40 minutes longer than Earth's day, our shifts precessed 40 minutes per day (in other words, someone who worked from 9:00 A.M. to 7:00 P.M. on Monday would work from 9:40 A.M. to 7:40 P.M. on Tuesday). My shift was generally in the middle of the night, but I was having so much fun I didn't care. In the ORTs I worked with other scientists in making decisions such as where to send the rover and what type of images to take. I also practiced writing sequences. By the time the final ORT was completed, I felt fairly confident that all of us were ready for the landing.

The landing on Mars on July 4, 1997 was one of the most spectacular days of my life and I shall never forget it. I can still remember the cheers and tears of joy when the first signals and pictures came back. It was exploration at its finest. However, despite all the excitement, I had a lot of work to do. During the first few weeks of operations I actually had very little time to devote to science. Much of my time was spent in meetings, where we discussed and decided upon future operations and heard what other scientists had found. (Luckily there were some scientists who had time to do science!) I also wrote IMP sequences that were sent up to the spacecraft and posted images on the Pathfinder Web site.

Finally, I was appointed "Rock Czar." Scientists and engineers were starting to name rocks and other features and it was my job (well, actually a very small part of my job) to keep track of these names and reject any that were distasteful. Surprisingly, this generated a lot of press. I received many phone calls and gave interviews about all of the funny names at the Pathfinder landing site (e.g., Yogi, Barnacle Bill, Scooby Doo). Activities started to wind down a little a month or so after landing. Although I continued to write sequences and update the Web site, I was now able to focus on my true interest: The geology of Mars. Since late September, when we stopped hearing from Pathfinder, virtually all of my time has been spent analyzing the plethora of images and other data. My primary areas of study are the geochemistry of the rocks and soil and the effects of wind on the surface. I have already attended two national scientific meetings where I presented the results of my investigations. I also recently wrote a paper that will soon be published in a scientific journal. Over the next few months I will continue to study Pathfinder data before moving on to other projects.

How Did I Get Here?

Since I was about eight years old I knew I wanted a career in some aspect of the space program. As a kid, I used to watch "Star Trek" and other science fiction programs. As I got older, I realized that a real, even more fascinating universe existed outside the TV set. By the time I was in fifth grade I was reading and collecting everything on astronomy and the space program I could get a hold of. At the same time, my former stepfather, who was a geologist (and still is), introduced me to some of his coworkers at the U.S. Geological Survey (USGS) who studied the geology of other planets. It then occurred to me that the best way to learn about planets was to study geology, not astronomy. Through high school my interest remained unabated. Between my junior and senior years I worked at the USGS studying data from the Mars Viking Landers. In 1985 I entered the University of Colorado and majored in geology. In 1988 I had a summer internship at the Lunar and Planetary Institute in Houston, Texas. I graduated from Colorado in 1989 and then went on to get a masters degree at Arizona State University in 1992. From 1992-1993 I again worked at the USGS, where I studied Mars and the Moon. In 1993 I started at the University of Massachusetts, where I earned my Ph.D. in geology in 1997.

What I Like Best and Least About my Job

The best thing about my job is that it is so exciting. To be on the cutting edge of exploration and to work with data that no one else has even seen before is a great thrill. The thing I like least is the instability. Funding for planetary science is tight and not knowing whether I will be supported in the future is a constant worry.

What I Enjoyed as a Kid

I was born and raised in Palo Alto, California. I really enjoyed being a kid. I had a tremendous imagination and would often think about going into space and other adventures. Some of my friends shared these interests with me. As I got older, I became interested in astronomy and science in general. I also was (and still am) fascinated by geography and history. In addition, I swam on a neighborhood swim team. I was a fairly average athlete, but did get a few first place ribbons. Despite these other activities and interests, I always knew I wanted a career in some aspect of the space program. I read lots of books and articles on the subject. I can remember the Voyager missions to the outer planets and how their views of previously unknown worlds expanded my mind and excited me. I worked hard in school. Even if I had a difficult time in a subject (which I often did), I would stick with it and never give up. My motivation and interest have brought me to where I am today.

People Who Influenced Me

There were many people who had a strong, beneficial impact on me. My family members were always supportive of my interests, as were most of my teachers through high school. Because I worked and visited the USGS in high school and in earlier years, I got to know several planetary geologists who inspired me, particularly Henry Moore (who I worked for in high school), Michael Carr (who I worked for years later), Dick Pike, and Don Wilhelms. I remember in the summer of 1985 I visited the USGS before heading off to start college in Colorado. At the time I was planning to major in aerospace engineering. Don Wilhelms showed me fascinating pictures of the Moon and explained how lunar history was derived from the study of these images. I was so enthralled that I immediately wrote to Colorado and told them I wanted to major in geology instead. I have never regretted that decision.


I am 31 years old and live in Los Angeles, California. I grew up in Palo Alto, CA and stayed there through high school. I have also lived in Colorado, Texas, Arizona, and Massachusetts. Last year I got married to the former Karen Mullaney of Melrose, MA. We met while I was in graduate school at the University of Massachusetts. She is also a geologist and works for an environmental firm. Long before I got hired on the Pathfinder project, Karen and I were engaged and had set a wedding date of June 29, 1997. That turned out to be right before Pathfinder landed on Mars. So, we had only a two-day honeymoon following our wedding, after which I had to return to JPL. Karen was amazingly understanding and patient. Her patience finally paid off when we took our delayed honeymoon to Hawaii in February and March of this year (1998).

I have a number of interests outside my job. I enjoy all kinds of physical activity, such as swimming, running, biking, weight lifting, and racquetball. I am currently a student pilot and hope to soon have my own private pilot's license. I enjoy reading about science, history, religion, and world affairs. I also like mystery and science fiction novels. At the end of a long day, Karen and I enjoy watching TV and playing with our pet rabbit. On weekends, when not tackling the errands that have accumulated during the week, we commonly go hiking, see movies, or eat at many of the great restaurants in the LA area. I would like to remain a planetary geologist. A goal of mine is to one day actually go to the Moon or Mars. Even if that does not happen (which is likely), I think I will continue to enjoy studying the planets from afar.

Learn more from my chats
August 5, 1998


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