Where did Earth’s water come from? In this episode of Planetary Radio, we explore how scientists are answering that question by studying a remarkably well-preserved record of the early Solar System: lunar samples brought back by the Apollo missions. Host Sarah Al-Ahmed is joined by Tony Gargano, postdoctoral fellow at the Lunar and Planetary Institute with the University Space Research Association and a research affiliate at NASA’s Johnson Space Center. Gargano studies lunar rocks and regolith to understand how planets form, evolve, and acquire key ingredients like water over time. By analyzing subtle chemical fingerprints preserved in Apollo-era lunar regolith, his work helps constrain how much water meteorites could have brought to Earth and what that means for our planet’s path to habitability.

The episode also features a short bonus segment with actor George Takei, recorded at the Academy Museum of Motion Pictures during a screening of “Star Trek IV: The Voyage Home.” Takei reflects on the enduring legacy of “Star Trek,” its influence on generations of scientists and explorers, and why he is excited about humanity’s return to the Moon in the Artemis era. He connects science fiction’s hopeful vision of the future with the real science helping us understand our origins today.

Discover more at: https://www.planetary.org/planetary-radio/2026-earth-water-apollo-moon-dust

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What does a NASA authorization bill actually do, and why does it matter? In this episode of Space Policy Edition, we dig into one of the most misunderstood but powerful tools Congress uses to shape the future of U.S. space exploration.

Host Casey Dreier, chief of space policy at The Planetary Society, is joined by Jack Kiraly, the Society’s director of government relations, for a deep dive into how NASA authorization bills work, how they differ from appropriations, and why they can have decades-long consequences for science missions, human spaceflight, and planetary defense. The discussion also reflects on a major recent win for space advocates: Congress’s bipartisan decision to protect NASA science funding.

Discover more at: https://www.planetary.org/planetary-radio/spe-what-is-a-nasa-authorization-bill

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What if Europa’s seafloor isn’t alive with activity after all?

This week on Planetary Radio, host and producer Sarah Al-Ahmed explores new research that reframes how scientists think about one of the Solar System’s most intriguing ocean worlds.

Sarah is joined by Paul Byrne, associate professor of earth, environmental, and planetary sciences at Washington University in St. Louis. Paul is the lead author of a new study suggesting that the seafloor beneath Europa’s global ocean may be geologically quiet today, potentially lacking the hydrothermal activity often associated with habitable environments on Earth. Together, they discuss how scientists investigate places we can’t yet observe directly and why Europa remains a compelling world to explore regardless of what we find.

Then, Bruce Betts, chief scientist of The Planetary Society, joins us for What’s Up to explain why Saturn’s moon Enceladus shows strong evidence for active hydrothermal vents beneath its icy crust, offering a fascinating contrast between two ocean worlds.

Discover more at: https://www.planetary.org/planetary-radio/2026-europas-quiet-seafloor

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