Course Descriptions

What is Astrobiology

Astrobiology is the study of life in the universe: its origin, evolution, distribution, and destiny. It is an intrinsically interdisciplinary or multidisciplinary field involving (among others) microbiologists, astronomers, geologists, planetary scientists, environmentalists, geneticists, and evolutionary biologists.

Astrobiology began in the middle 1990s as a research discipline. However, the subject of life in the universe had for a long time been a topic in a variety of introductory astronomy and general science courses, often in association with SETI (the search for extraterrestrial intelligence). The popularity of these courses, as well as the growing interest in astrobiology as a research discipline, has encouraged new courses in “astrobiology”, or “life in the universe”, or “the search for life in the universe”. Initially most of these courses have been offered in astronomy departments, but we may hope that in the future such courses will also find a home within biology and geology departments.

In the Preface to one of the first college textbooks in astrobiology, Jeff Bennett, Seth Shostak, and Bruce Jakosky write: “Given the intense research effort being undertaken by the scientific community and the long-standing public fascination with the search for life, it should be no surprise that the subject of astrobiology has become one of the most publicly visible sciences.” This webpage is dedicated to encouraging the teaching of astrobiology at the college level, especially as a broadly-based introductory science course for non-science students. Perhaps the development of stimulating new courses in astrobiology will help in a small way to improve the understanding of science by the general public.

David Morrison
Senior Scientist, NASA Astrobiology Institute

Samples of course content

Below is an outline for a nominal “Astrobio 101” course, based in part on available textbooks but also considering the contents of the astrobiology discipline adopted by the research community. The most striking differences between the current texts and the research agenda are as follows: (1) A major part of current research deals with the origin and evolution of microbial life, with special emphasis on life in extreme environments. In contrast, these topics typically occupy only about 15% of the texts examined. (2) Possible biomarkers, especially detectible evidence of life on distant planets, is more prominent as a research topic than in the texts, perhaps because it is a relatively new area of emphasis. (3) The study of the future of life, including the responses and possible adaptation of terrestrial life to conditions in space or on other planets, is hardly discussed in the texts. (4) SETI, which represents a small (but enthusiastic) research area, is treated extensively in the texts. (5) The texts also discuss interstellar travel, UFOs, and possible contact with intelligent aliens, areas of wide public interest that do not appear in the astrobiology research agendas.

NOMINAL TOPICS FOR ASTROBIO 101

• The nature of science and the scientific method; distinction between historical and experimental sciences; distinction between hypothesis driven and exploration driven research

• Our place in the universe: The Copernican revolution; the Earth as a planet; the concept of deep time (or geological time); the interrelatedness of life; evolution by natural selection

• From stardust to humans: Synthesis of elements; organic chemistry in space; the synthesis and delivery of biogenic materials

• Definitions of life: Roles of metabolism, inheritance, interaction with environment; non-carbon-based life; artificial life

• Fundamentals of cell biology: The cell and its constituent parts; extraction of energy from the environment; photosynthesis

• Fundamentals of genetics: DNA and RNA; the phylogenetic tree of life; the concept of last common ancestor

• Origin of life on Earth: Environment; origin of volatiles and organic chemicals; Miller-Urey synthesis; impact frustration of life

• Co-evolution of life and the environment: The changing atmosphere; geological timescale; mass extinctions and speciation

• Life in extremes: Tolerable range of temperature, salinity, acidity, radiation; extreme environments (e.g., hot springs, marine hydrothermal vents, sea ice, salt water, deep subsurface)

• Planetary habitability: The role of liquid water; solar luminosity and surface temperatures; greenhouse effect; loss of planetary atmospheres

• Mars: Current surface conditions and habitability; evidence of different past climates; the Viking search for life; Mars rock ALH84001

• Outer solar system: Europa and Titan environments, prospects for investigation

• Extrasolar planetary systems: Techniques to discover planets (Doppler, photometry, astrometry, imaging); comparison of other systems with ours

• Life on distant planets: Conditions expected in other planetary systems; biomarkers; alternative evolutionary pathways

• SETI: The Drake equation; strategies for detecting signals; implications of contact

• Expansion of life beyond the Earth: Effects of space exposure to radiation and microgravity; panspermia; planetary protection; terraforming Mars

• Societal context: UFOs and alien abductions; the Face on Mars; astrobiology and science fiction; societal implications of astrobiology

Syllabus samples

Several examples of “Astrobio 101” courses will be listed, beginning with a fictitious nominal course syllabus derived primarily from an examination of the three textbooks that are most often used today for astrobiology courses. These three texts are:

(1) Life in the Universe by Jeffrey Bennett, Seth Shostak & Bruce Jakosky (Addison Wesley, 2003)

(2) The Search for Life in the Universe (3rd ed) by Donald Goldsmith & Tobias Owen (University Science, 2002)

(3) The Search for Life on Other Planets by Bruce Jakosky (Cambridge, 1998)