<p>Martin Bizzarro tells what zircon crystals reveal about the geological history of Mars.</p>

Eruption of Steamboat Geyser

Welcome to Science Sessions, the PNAS podcast program. Listen to brief conversations with cutting-edge researchers, Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in PNAS, plus a broad range of scientific news about discoveries that affect the world around us.