On the Cover: Carl Sagan's scientific life centered on the search for life in the universe. The two images on our cover symbolize the range of his work: the amino acid glycene, seen here in crystallized form, is one of the crucial building blocks of life on Earth. Its spectra have been detected in gas and dust clouds among the stars, suggesting that it—and the life that can spring from it—may be common in the universe. The nearby planet Mars has carved into its surface evidence that it once possessed a climate that may have supported life. Here Ma'adim Vallis, a 600-kilometer-long channel (400 miles), drains into the crater Gusev. Channels like this, with a morphology typical of earthly rivers, show that water once flowed on Mars. Discoveries like these, of the elements of life, propelled Carl's work
4 Carl Sagan, Teacher: "Carl Sagan taught the whole world," writes one of his students, Chris Chyba. Yet a fortunate few had a traditional and intimate teacher-student relationship with Carl in his primary career as a professor of astronomy. Chris recounts the effects Carl had on their lives.
8 Carl Sagan, Spokesman for Science: It was in his role as a spokesman and popularizer of science that Carl was best known—and sometimes controversial. Hans Mark often found himself opposing Carl on some issues, but he treasured Carl's ability to put science within the reach of anyone who wanted to learn.
11 Carl Sagan, Partner in Exploration: It's hard to imagine two more divergent personalities than Carl Sagan and Bruce Murray. For over 30 years their careers entwined, and they found a way to work together—and formed the Planetary Society.
16 Carl Sagan, Scientist: Carl's very real scientific accomplishments were sometimes overshadowed by his persona as a popularizer. Renowned astrophysicist Frank Drake reminds us how much Carl contributed to the advance of planetary science.
20 Ode to the Alien: Poet and author Diane Ackerman wrote this provocative and evocative piece at Carl's request.
22 Carl Sagan, Visionary: Apollo 11 astronaut Buzz Aldrin knew and admired Carl for decades. When the Planetary Society asked him to speak at our commemoration, Buzz commission this speech from writer Wyn Wachhorst.
23 The Future of the Planetary Society: The Planetary Society has lost its most illustrious spokesman, but the organization remains strong, and with the help of our friends and our members, we can become a stronger and more effective force for planetary exploration. Louis Friedman reports.
3 Members' Dialogue Worldwide cooperation; the Mars Rock issue.
26 News & Reviews Bringing about change in science education.
27 Society News Red Rover, Red Rover lets you drive on Mars!
28 Basics of Spaceflight The Deep Space Network.