This article presents a historical preface to the Astrobiology special collection by introducing the actors, timeline, and intellectual framework involved in the National Aeronautics and Space Administration's (NASA) Viking mission. The authors pull information from scholarly articles, historical records, and the personal notes of Viking scientists uncovered this year and currently en route to the National Archives. Revisiting the legacy of Viking here provides a brief look into the science that continues to inform the practice of astrobiology and the creative spirit that inspires its scientists. All figures presented in this article have not previously been publicly available and will be made so later this year in the Exobiology Branch Collection at NASA’s Ames Research Center Archives (collection ARC11.17). The authors encourage space history and astrobiology researchers to consult the soon-to-be accessioned Viking-era records housed in the Ames archives for new insights into America’s first landing on Mars.
Ames Research Center. Preliminary Project Development Plan: Mars ‘73 Lander Project Life Detection Experiment. (NASA Ames Research Center Archives. ARC11.17, Exobiology Branch Collection, 1960–1996, FRC-000043). NASA Ames Research Center: Moffett Field, CA; 1968.
2.
AndersonC. The first rover on Mars - the Soviets did it in 1971. The Planetary Report July/August. Planetary Society; 1990.
3.
BiemannK, OroJ, ToulminPIII, et al.Search for organic and volatile inorganic compounds in two surface samples from the Chryse Planitia Region of Mars. Science1976;194(4260):72–76.
4.
ClarkBC. Viking Science–1. Astrobiology2026;26. in press.
5.
EzellEC, EzellLN. On Mars: Exploration of the Red Planet, 1958–1978. (NASA Special Publication 4212). U.S. Government Printing Office: Washington, DC; 1984.
6.
ForgetF, HourdinF, FournierR, et al.Improved general circulation models of the martian atmosphere from the surface to above 80 km. J Geophys Res1999;104(E10):24155–24175.
7.
FrenchBM. Mars: The Viking Discoveries. (EP-146). NASA, Office of Space Sciences, Office of Lunar and Planetary Programs: Washington, DC; 1977.
8.
HaberleRM, de la Torre JuárezM, KahreMA, et al.Detection of Northern Hemisphere transient eddies at Gale crater, Mars. Icarus2018;307:150–160.
9.
HaberleRM, PollackJB, BarnesJR, et al.Mars atmospheric dynamics as simulated by the NASA Ames General Circulation Model: 1. The zonal‐mean circulation. J Geophys Res1993;98(E2):3093–3123; doi: 10.1029/92JE02946
10.
HoganT. Lessons learned from the Space Exploration Initiative. NASA History Division Newsletter2007;24(4):1–2, 4–5.
11.
JonesKL, ArvidsonRE, WallSD, et al.One Mars year—Viking lander imaging observations. Science1979;204(4395):799–806.
12.
JoshiM M, LewisS R, ReadP L, et al.Western boundary currents in the Martian atmosphere: Numerical simulations and observational evidence. J Geophys Res1995;100(E3):5485–5500; doi: 10.1029/94JE02716
13.
KleinHP. The Viking biological experiments on Mars. Icarus1978;34(3):666–674.
14.
KounavesSP, HechtMH, KapitJ, et al.Wet chemistry experiments on the 2007 Phoenix Mars Scout Lander: Data analysis and results. J Geophys Res2010;115(E1) E00E10.
15.
LevinGV, StraatPA. Labeled Release—an experiment in planetary biology. Bioscience1976a;26:522–529.
LevinGV, StraatPA. The case for extant life on Mars and its possible detection by the Viking Labeled Release experiment. Astrobiology2016;16(10):798–810.
18.
LevinGV. Detection of metabolically produced labeled gas: The Viking Mars lander. Icarus1972;16(1):153–166.
19.
MazurP, BarghoornES, HalvorsonHO, et al.Biological implications of the Viking mission to Mars. Space Sci Rev1978;22(1):3–34.
20.
McKayCP, QuinnRC, StokerCR. The Viking biology experiments on Mars revisited. Icarus2025;431(28):116466.
NASA. Planetary Mission Summaries—1980. (715-93). NASA and Jet Propulsion Laboratory, Advanced Studies Technology and Space Program Development: Pasadena, CA; 1980a.
28.
NASA. Technology Presentations to the Solar System Exploration Committee. (725-46). NASA and Jet Propulsion Laboratory: Pasadena, CA; 1981.
29.
NASA. The Viking Expedition. NASA biology: On Earth and in space, Series. NASA: Washington, DC; 1980b. Available from: https://www.youtube.com/watch?v=1ZFlYwJ6Phk [January 6, 2026].
30.
NASA. Viking ‘79 Mission to Mars Briefing to Planetary Remote Sensing Working Group. (NASA Ames Research Center Archives. ARC11.17, Exobiology Branch Collection, 1960–1996, FRC-000239). NASA Ames Research Center: Moffett Field, CA; 1972.
National Research Council. Summary of Viking findings relevant to Martian biology. In: Post-Viking Biological Investigations of Mars. The National Academies Press: Washington, DC; 1977, pp. 2–11.
34.
Navarro-GonzálezR, NavarroKF, de la RosaJ, et al.The limitations on organic detection in Mars-like soils by thermal volatilization–gas chromatography–MS and their implications for the Viking results. Proc Natl Acad Sci USA2006;103(44):16089–16094.
SnyderCW. The extended mission of Viking. J Geophys Res1979;84(B14):7917–7933.
37.
StokerC. The search for life on Mars: The role of rovers. J Geophys Res1998;103(E12):28557–28575.
38.
TierneyMS. The Chances of Retrieval of Viable Microorganisms Deposited on the Moon by Unmanned Lunar Probes. (Report No. SC-M-68-539; NASA-CR-96121). Sandia Laboratories: Albuquerque, NM; 1968.
39.
YoungRS. Survey of Life-Detection Experiments for Mars by the Life-Detection Experiments Team. (NASA Ames Research Center Archives. ARC11.17, Exobiology Branch Collection, 1960–1996, FRC-000238). NASA Ames Research Center: Moffett Field, CA; 1963.
