Jack “Dr. Rock” Farmer, former professor of geobiology in the School of Earth and Space Exploration at Arizona State University (ASU), passed away on February 22, 2023. His research interests included biological mediation of sedimentary processes, the microbial fossil record of the Precambrian biosphere, and the origin and early evolution of animals.

Farmer’s career spanned nearly 50 years as a paleontologist and an astrobiologist, and he helped pioneer the field of exopaleontology. Throughout his career, he played crucial roles in contributing to the development of NASA’s exploration strategies, particularly in the search for fossil biosignatures on Mars. Much of his research focused on understanding the factors that control biosignature preservation and how this knowledge can be translated into strategies for the search for evidence of past life on the Precambrian Earth or other planets, like Mars.

Prior to joining the faculty at ASU, Farmer was on the faculty of the Department of Earth and Space Exploration at UCLA (1986–1991) and a research scientist in the Exobiology Branch of NASA’s Ames Research Center (1991–1998). In 2001, he testified on “Life in the Universe” before the Subcommittee on Space and Aeronautics, Committee on Science, House of Representatives, One Hundred Seventh Congress.

Farmer was instrumental in promoting the exploration for a martian fossil record and in the selection of the landing sites for Mars Pathfinder and the Mars Exploration Rovers. He served on the science definition teams for the Mars Odyssey and Mars Reconnaissance Orbiter missions, was a participating scientist on the Mars Exploration Rover mission, and was a member of the CheMin instrument team on the Mars Science Laboratory mission, which landed at Gale Crater on Mars on August 6, 2012.

Farmer served as a past director of ASU’s NASA-funded Astrobiology Program. He was a charter member of the Executive Council of NASA’s Astrobiology Institute (NAI) from 1998 to 2003 and chairperson of the NAI Mars Focus Group (2000–2003) and of the community-based Mars Exploration Program Analysis Group (MEPAG) in 2003. He was also an active member of the Geological Society of America (GSA) and was co-founder and past chairperson for GSA’s Geobiology/Geomicrobiology Division and a recipient of the Division’s 2012 Award for Outstanding Contributions to the fields of Geobiology and Geomicrobiology. He was a Sequoyah Fellow of the American Indian Science and Engineering Society (AISES) and an Associate Editor of the journals Astrobiology and the International Astrobiology Journal.

Farmer was also a past member of NASA’s Space Sciences Advisory Committee and served on several National Research Council (NRC) boards and committees, including the Space Studies Board (SSB), the Committee to Review the NASA Astrobiology Institute, the Committee for the Review of the NASA Science Mission Directorate Science Plan, and the Committee on an Assessment of Balance in NASA’s Science Programs. He recently chaired the NRC SSB’s Committee on the Review of Planetary Protection Requirements for the Mars Sample Return Missions Space Studies Board, Division on Engineering and Physical Sciences of the National Research Council.

Farmer was part Native American (Chickasaw and Cherokee) and proudly engaged with tribal communities. Wearing his “Dr. Rock” name badge, he did not hesitate to share his passion for the beauty of geology in many public outreach efforts over the years. He was also a kind and empathetic mentor, always striving to help guide his students toward excellence and opening up opportunities for them to get involved in exciting mission-based, field, and lab projects. He had a deep passion for exploring varied field environments, collecting samples in situ that could be studied in the lab, and instilling in his students an understanding of their contextual environment.

A kind, patient man who left a positive impact in his community, Farmer will be remembered fondly as a compassionate and skilled scientist whose legacy will live on in his students and colleagues.

— Portions of text courtesy of Arizona State University and colleagues Charlene Estrada, Marisol Juarez Rivera, Jon Lima-Zaloumis, Jorge Nunez, Svetlana Shkolyar, and Kathleen Campbell