2008 Medals & Awards

G.K. Gilbert Award The scientific achievements from the of the next generation of scientists. Ladies TES experiment are too numerous to list here, and gentlemen, I am honored to present the Presented to Philip R. Christensen but we can highlight one that stands apart 2008 recipient of the G. K. Gilbert Award from all the others, and which was critically by the Planetary Geology Division of GSA, important for planetary geology, and that Professor Phil Christensen. was the proposed identification of hematite in specific locations on Mars based on TES data. If this hypothesis could be shown to be Response by Philip R. Christensen correct, it would have profound implications Let me begin by expressing how for the history of Mars and the evolution of deeply honored I am to be receiving the its surface. Based on this hypothesis, one of G.K. Gilbert award. When I am asked what the Mars Exploration Rover (MER) sites was it is I do, I always respond by saying that I selected to test the idea and provide “ground am a geologist - not a Mars scientist, or a truth” for the IR remote sensing data. As geophysicist, or an instrument builder - so is well known now, the MER Opportunity receiving this award from the Geological results confirmed the existence of hematite Society of America is truly an honor. I would and, coupled with other observations, have like to specifically thank Ron Greeley and shown the critical role played by water in all those who supported my nomination, and Philip R. Christensen Mars’ surface history. Ron for his very generous introduction. This Arizona State University Allow me to segue into what I believe award is especially meaningful to me because is a unique accomplishment by Phil. During I have long admired G.K. Gilbert and have the operation of TES, he and his technical been intrigued by many of the same scientific and scientific teams developed concepts for questions that he pursued throughout his Citation by Ronald Greeley a “mini-TES,” capable of operating from career. I grew up in the west, having been Mars’ surface to complement observations born in Utah and lived in Kansas and I first met my friend and scientific from orbit, as well as a “next-generation” IR California. Each summer my family would colleague, Phil Christensen, during the instrument, the THEMIS (Thermal Emission drive across the west to visit our scattered Viking mission to Mars in 1976. Those were Imaging System). Mini-TES was proposed relatives, and during those long drives I spent indeed heady times, with the first successful as part of the MER Athena payload, while many hours looking out the window of our landings on the Red Planet, and the successful THEMIS was proposed for the Mars Odyssey car at the mountains and landforms. I didn’t operation of two spacecraft in orbit, with all orbiter. All of these experiments were realize it at the time but I was becoming a four spacecraft operating concurrently. Phil selected for flight, leading to what I believe is geologist. Much like Gilbert, I was fascinated was part of Hugh Kieffer’s Thermal Infrared unprecedented in planetary science by a PI— by the western landscape and wondered at Mapping Spectrometer team, which allowed the operation of four instruments all operating its formation and history. My family liked him not only to hone his skills in the science concurrently: TES on Mars Orbiter, Mini- to explore out of the way places and we of IR remote sensing, but also to learn the TES on Spirit and Opportunity, and THEMIS probably traveled many of the same routes complexities involved with flight-qualified on Mars Odyssey. that Gilbert did, seeing landscapes that have planetary instruments. After coming to Throughout this period of intense not changed much since his time. When I was Arizona State University, Phil was able to instrument development, operation, and data 12 my parents gave me a telescope and, again put those skills to use through his innovative analysis, Phil conducted front-line research like Gilbert, I spent countless hours looking application of the IRTM data to solve some of in terrestrial remote sensing and field work, at the Moon. The only features I could see the mysteries of Mars, as well as to position and trained a cadre of students and post-docs with my small telescope were the craters, and him to propose successfully the Thermal who today are leading planetary scientists. in reading the few books about the geology of Emission Spectrometer (TES) instrument for Incredibly, at the same time, Phil and his the Moon I quickly learned of Gilbert’s early the ill-fated Mars Observer (MO) mission. team developed the premier NASA education hypothesis for crater formation and his role Anyone who has suffered a spacecraft and outreach program for Mars, leading to in shaping our understanding of the Moon’s failure can relate to the agony experienced thousands of teachers and students who are history. Finally, like Gilbert I have worked to by Phil and his team during the attempted now better equipped to understand the Red bring quantitative analysis to geology. Hugh insertion of Mars Observer into Mars orbit. Planet and planetary science in general. As Kieffer instilled in me the understanding that The silence was deafening, awaiting the part of this activity, Phil was invited by China in order to study the planets it is necessary never-received signal from MO; later analysis to show-case Mars exploration, representing to make quantitative measurements and indicated that the spacecraft had experienced the first University to do so. Attending by apply quantitative models. Following Hugh’s a catastrophic explosion. Not to be deterred, some thousands of visitors, the exhibit helped inspiration I have spent much of my career Phil worked diligently to build the case for pave the way for China to join the “deep- working to build instruments that give us the a re-flight to achieve the original science space” club for planetary exploration. data we need to advance our knowledge of objectives of the MO mission. Although it In summary, Phil has set the “gold the processes by which planetary surfaces would take three subsequent orbiters to meet standard” for planetary geology through evolve. this overall goal, Phil’s TES experiment was his scientific discoveries, development The past 30 years have been a selected among the first to fly on the highly of successful leading-edge instruments, remarkable period in planetary exploration, successful Mars Global Surveyor spacecraft. community service contributions, and training and I consider myself to be very fortunate

The Geological Society of America 2008 Medals & Awards to have participated in this modern age thank my wife Candace and our kids Kevan investigate Mars in the same way and to the discovery. Throughout these years many and Alexandra who have led me to understand same depth that geologists investigate the people have inspired me, and many more have what is truly important in life. Earth. We are now asking questions about contributed to the results that have defined my One of the greatest pleasures I’ve Mars that are as complex as those that Gilbert career. Hugh Kieffer has played a remarkable had over the past 25 years has been the asked about the American west over 100 years role, from the job he gave me cutting up opportunity to work closely with a remarkable ago. I am extremely proud to have helped Mariner 9 images as an undergraduate, to his group of engineers, including Still Chase and form a new generation of geologists who are mentoring me through graduate school, to his Steve Silverman. This experience has made pressing these questions forward. Their talent willingness to point me in the right direction a deep impression on me about the benefit, and enthusiasm give me great confidence that but let me find my own way as I attempted to and personal enjoyment, that comes when the next 30 years will see an explosion in our build flight hardware. Ron Greeley provided scientists and engineers work closely with a understanding of our solar system and the a wonderful opportunity for me at ASU and shared vision. increasing application of geologic methods I have benefited greatly from his guidance. The future of planetary geology is to planets beyond our own. In closing, let me From Ron I have learned the importance remarkably bright. In my lifetime our say again how honored I am to have received of participating in the exploration process. perception of Mars has changed from a point this award, how rewarded I feel at having had Ray Arvidson, Bruce Jakosky, Rich Zurek, of light in the night sky to a complex planet the opportunity to work with a remarkable Arden Albee, and Mike Malin are among the we are coming to know as well as our own. group of students and young scientists, and many who have inspired and tempered my The images we have of Mars rival the views how excited I am about the future of planetary thinking and provided encouragement and I had out the window of our family car, and geology. stimulation. Finally, I would like to sincerely the data being acquired will allow us to

The Geological Society of America