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Astrobiology collage


with guest Dr. Chris McKay from the NASA Ames Research Center

Dr. Chris McKay

In this episode, we're going to talk about astrobiology and the search for life in the universe. Living things have been found in very extreme environments on Earth, like hot springs, or near underwater volcanoes, or hidden beneath the Antarctic ice pack, or even inside rocks. Could life exist in those same kinds of places on other planets? When we look for signs of life on other worlds, what would we look for? How do we search it out? And, how would we know if what we find is caused by living things -- or some other physical process?

Listen (mp3, 8.7 MB)

Download Transcript (pdf)

Further Activities & Resources


Written and narrated by Carolyn Collins Petersen

Original music by Geodesium

Special thanks to Dr. Christopher P. McKay

Produced by the Astronomical Society of the Pacific

Web page materials by Andrew Fraknoi

Exploring Astrobiology Further:
A Collection of Activities and Resources to Get Behind the Headlines

Andrew Fraknoi (Foothill College & ASP)
May 2009

Here are some materials for informal science educators (and their audiences) to delve more deeply into the topics discussed in this month's "Astronomy Behind the Headlines" podcast. We'll look at three topics inspired by Dr. McKay's comments: an introduction to astrobiology, the search for life on Mars, and the Kepler mission's search for Earth analogs.

We know that informal educators are often very busy. Thus, while there are wonderful full-length books on each of these topics, here we will restrict ourselves to materials that are accessible on the Web with the click of a few keys.

A. Astrobiology

A1. Background

A2. Activities

B. The Search for Life on Mars

B1. Background

B2. Activities

C. The Kepler Mission

C1. Background

C2. Activities

A. Introduction to Astrobiology

A "black smoker"
A "black smoker" -- an undersea vent where the heat and chemical energy from inside the Earth make a variety of living things possible.

Astrobiology (which used to be called exobiology) is the term scientists use for the study of the "origin, evolution, distribution, and future of life in the universe." That's quite a broad undertaking, if you think about it! Astrobiology is a relatively new field that combines the work of astronomers, biologists, chemists, paleontologists, ecologists, and geologists in an effort to determine whether Earth has the only examples of life in the cosmos or whether living things on Earth might have "cousins" among the planets and the stars.

A1. Background Information

Are We Alone?: A Radio Show on Astrobiology (hosted by Seth Shostak and Molly Bentley). This humorous and informative program features many segments and interviews on life beyond Earth:

Ask an Astrobiologist (NASA's David Morrison, one of the founders of astrobiology, answers public questions; has a rich and searchable set of questions already answered):

New Scientist Magazine "Instant Expert" Page Introducing Astrobiology:

What Is an Astrobiologist and How Do I Become One (from the private Astrobiology web site by SpaceRef, with good questions and answers):

A2. Activities

connection between life and the universe
NASA illustration showing the connection between life and the universe.

Astrobiology Educator Guide: A 60-page NASA booklet, available in PDF format, with 5 activities for classrooms and museum workshops, at about middle-school level. Several of the activities involve cards and games:

The Living Earth (environments for life): A Sample Activity from the SETI Institute's Voyages through Time Curriculum on Cosmic Evolution:

Sample Activities from Astrobiology: An Integrated Curriculum (a high-school guide, developed by TERC):

a. Extraordinary Claims (how the public can judge media accounts of life elsewhere):

b. WebQuest: The Xtreme Files (surfing for information on Earth life in extreme environments):

c. Is the Moon Habitable? (how it differs from Earth):

Activities on Astrobiology from Science Scope Magazine (National Association of Science Teachers):

B. The Search for Life on Mars

B1. Background Information

Mars Exploration Rover
Mars Exploration Rover instruments examine Mars.

Of all the planets with which we share our solar system, Mars is perhaps the most likely to have harbored at least the beginnings of life. At the very least, we now have good evidence, from orbiting and roving space missions that long ago there was abundant water on the red planet's surface. NASA's missions to Mars are designed to "follow the water" -- to search for the remains of life where liquid might have been present or frozen water still exists.

Brief Introduction to Mars:

NASA's Mars Exploration Program (Jet Propulsion Laboratory web site):

Mars Article from World Book Encyclopedia by astronomer Steven Squires (at NASA):

Mars pages at the "Nine Planets" site:

Google Mars (an expandable, explorable map of Mars):

B2. Activities

Mars Spirit Rover
The Mars Spirit rover looks out at Gusev Crater in this photomosaic.

Phoenix Mars Mission Activities (includes modules on following the water and the search for life):

Exploring Mars: Old, Relatively (a brief activity showing how geologists use images from Mars to figure out the ages of features):

The Martian Sun-Times (groups develop a newspaper that gives news, weather, and other martian information):

Mars Activities (a 131-page guide developed by JPL and Arizona State U.): http://marsprogram.jpl.nasa.gov/classroom/pdfs/MSIP-MarsActivities.pdf

Mars Exploration Curriculum Modules (a set of explorations developed by TERC for JPL, with some ideas that could be used in informal settings as well): http://marsprogram.jpl.nasa.gov/education/modules/webpages/modulepage.htm

Mars and Earth Afterschool Activities Guide:

American Museum of Natural History Mars Activities (with out of school applications):

C. The Kepler Mission

Kepler spacecraft
An artist’s impression of the Kepler spacecraft.

One way that astronomers can search for planets around other stars is to catch a planet moving in front of its star as seen from Earth. When a planet covers up part of its star, it is called a transit, and the blocked light makes the star a tiny bit dimmer. With real good light-measuring devices (called photometers), astronomers can detect this miniscule dimming. It's easier to do this from space, where the changing effects of the Earth's atmosphere are not a factor. On March 6, 2009, NASA launched the Kepler space telescope into orbit, designed to look at 100,000 stars at the same time, and to measure if any of them have a slight change in their light output. While big planets like Jupiter will cut down a star's light more, Kepler should be accurate enough to detect a smaller planet like the Earth crossing the face of its star.

C1. Background Information

Kepler Mission Website at NASA:

Brief Introduction to the Kepler Mission (from the SETI Institute):
http://www.seti.org/Page.aspx?pid=908 and
http://www.seti.org/Page.aspx?pid=909 and

Photometry and Transits (from the Planetary Society): http://www.planetary.org/explore/topics/extrasolar_planets/

Planet Quest (a general web site on finding planets around other stars, from JPL): http://planetquest.jpl.nasa.gov/

Transit of Venus (a newsletter on a more local 2004 transit event when Venus moved across the face of the Sun):

C2. Activities

Kepler Mission Activities Page:

Kepler Mission Activities from the Night Sky Network:

Kepler Mission Models and Simulations:

Exploring Strange New Worlds Activity from Night Sky Network (a more general activity on how astronomers learn about planets):