On the Cover: Our experience in exploring the Moon revealed no danger to earthly life from lunar life-forms—there were none—but the case on Mars may not be so easy. We know that some terrestrial life-forms—such as the stromatolite-building algae (insets, center and right)—are not always easily identified as living things. Martian life-forms may be more difficult to recognize. Dry, ancient riverbeds (such as Kasei Valles, background) tell us that Mars once supported liquid water and, therefore, the possibility of life. Can we be sure there is no life there now, that we will not contaminate Mars ourselves, or that samples sent to Earth from Mars will not endanger our biosphere?
3 Is It Dangerous to Return Samples From Mars to Earth? Carl Sagan poses a question for which no one has the definitive answer.
4 Protecting Our Planet, Preserving Other Worlds: Donald DeVincenzi has put together this special issue on planetary protection as an introduction to our members:
- 5 Where No One Has Gone Before...What is Planetary Protection, Anyway? by John Rummel and Michael Meyer
- 6 Rocks in Quarantine: Apollo's Lessons for Mars, by John Bagby
- 10 Lessons From Viking: The Search for Life on Mars, by Norman Horowitz and Arden Albee
- 10 Caution and Humility: Where There's Water... by Elliott Levinthal
- 13 Lessons From Evolution: Ruling Out Danger, by Thomas Jukes
- 13 Considering the Improbable: Life Underground on Mars, by C. P. McKay, M. Ivanov, and P. J. Boston
- 16 Swapping Rocks: Exchange of Surface Material Among the Planets, by H. Jay Melosh
- 20 Anticipating the Reaction: Public Concern About Sample Return Missions, by Margaret Race
24 Readers' Service Books on the Apollo missions for the 25th anniversary.
25 World Watch NASA and Russian Mars missions.
26 News & Reviews Remembering artist Chesley Bonestell.
27 Society News/Members' Dialogue Winners of the Name the Rover Contest.
28 Q&A Helium 3; Mercury's magnetosphere.