The Universe in the Classroom

Responsible Exploration: Protecting Earth and the worlds we explore from cross contamination

What do we look for to 'see' Life?

General Characteristics of Life on Earth:




Has organization or structure that is recognizable at some level (body, cells, tissues, organs, biological molecules, etc.)

Uses Energy/Metabolizes

Able to take energy from the environment, transform it and 'use' it


Development or expansion of organism in size and complexity


Give rise to others of the same type


Capable of using energy for self-propelled movement, however subtle


Organisms can perceive the environment and react to it


Have units of inheritance, a genetic code, that passes from parent to offspring — and that controls physical, chemical and behavioral traits


Organisms have structures, behavior, and abilities that suit their life form to their environment


Populations of organisms change over time

What to Look For with Extraterrestrial Samples: Universal Properties of Life that are "Measurable"

About the Author

Dr. Margaret S. Race is an ecologist currently working with NASA through the SETI Institute in Mountain View, CA. Dr. Race's professional interests focus on the scientific and policy implications of large-scale projects involving science, technology and development. Her current work focuses on environmental impacts, legal and policy issues and risk communication related to solar system exploration and the search for extraterrestrial life. Recently, she has served as a member of two major National Research Council (NRC) studies: one on Issues in Mars Sample Return and the other on Sample Return from Small Solar System Bodies. For the last several years she has been an organizer and participant in NASA international workgroups developing containment and planetary protection protocols for the upcoming Mars Sample Return mission. Throughout her career she has also been actively involved in science education and outreach for K-12 schools, museums, mass media and the general public.

In addition to her appointment at SETI Institute, Dr. Race is a research affiliate with the Energy and Resources Group at University of California at Berkeley. Previously, she was Assistant Dean in the College of Natural Resources at UC Berkeley, and a faculty member in the Human Biology Program at Stanford University.

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