Planetary Radio: Space Exploration, Astronomy and Science

On July 14, 2015, NASA’s New Horizons spacecraft made its historic flyby of Pluto, transforming our understanding of this distant world. Ten years later, we’re celebrating that iconic moment and the mission that made it possible. We begin with Alan Stern, principal investigator of the New Horizons mission, who reflects on the mission’s origins, its most surprising discoveries, and what comes next as New Horizons continues its journey through the Kuiper Belt. Then we check in with Adeene Denton, NASA postdoctoral program fellow at the Southwest Research Institute, who just returned from the “Progress in Understanding the Pluto System: 10 Years After Flyby” conference held at the Johns Hopkins University Applied Physics Laboratory. Adeene shares highlights from the event, which brought together scientists to explore new results from New Horizons, JWST, Hubble, and ground-based observatories on Pluto, Charon, and the broader Kuiper Belt. Finally, Planetary Society Director of Government Relations Jack Kiraly joins us with a major update on the ongoing fight to protect NASA science from devastating budget cuts. And don’t miss What’s Up with our Chief Scientist, Bruce Betts. We’re talking Arrokoth, the most distant Kuiper Belt object New Horizons visited after Pluto. Discover more at: https://www.planetary.org/planetary-radio/2025-new-horizons-pluto-flyby-10th-anniversarySee omnystudio.com/listener for privacy information.

Author Andy Weir was as shocked as anyone when The Martian became a top bestseller novel in the US. He repeated that achievement with his equally mind-blowing science fiction masterpiece Project Hail Mary. Former Planetary Radio host Mat Kaplan welcomed Andy in April of 2023 for the first livestreamed author conversation in The Planetary Society's member book club. Now, with the film version of Project Hail Mary approaching, we’re proud to begin making these insider interviews available to Planetary Radio listeners. We’ll post them on the third Friday of each month. Join us as we talk with Andy about his obsession with getting the science right while his reluctant and unlikely hero attempts to save humanity from a deep space scourge. Discover more at: https://www.planetary.org/planetary-radio/book-club-andy-weirSee omnystudio.com/listener for privacy information.

What happens when scientists, students, space communicators, and refugee engineers float together in zero gravity? Former Planetary Radio host Mat Kaplan joins a remarkable group of flyers aboard a Zero-G flight organized by Space for Humanity. You’ll hear from participants and mentors including Emily Calandrelli, Sian Proctor, and Roxy Williams, as well as Space for Humanity Executive Director Antonio Peronace and Zero-G CEO Kevin Sproge. Together, they share how a few moments of weightlessness offered a powerful shift in perspective. We explore the mission to make space more inclusive, the awe of the “overview effect,” and what it means to carry that inspiration back down to Earth. Then, Bruce Betts joins us for What’s Up. Discover more at: https://www.planetary.org/planetary-radio/2025-mat-kaplan-zero-gSee omnystudio.com/listener for privacy information.

The Vera C. Rubin Observatory has shared its first public images, revealing millions of galaxies, stars, and asteroids in stunning detail. Stephanie Deppe, astronomy content strategist at Rubin Observatory, joins us to explain what makes these images so revolutionary, how the observatory works, and what’s coming next as Rubin prepares for its ten-year Legacy Survey of Space and Time. Later in the show, we reflect on the life and legacy of the observatory’s namesake, Vera Rubin, the groundbreaking astronomer who provided the first convincing evidence of dark matter. Jess Soto, STEM Strategies Coordinator at Mount Wilson Observatory and creator of Science Women Shirts, reflects on Rubin’s efforts to open up opportunities for women in space science. Then we close out the show with Bruce Betts in our regular What’s Up segment, featuring the discovery of a brand-new interstellar object, 3I/ATLAS, the third known object to travel through our Solar System from interstellar space. Discover more at: https://www.planetary.org/planetary-radio/2025-first-images-rubin-observatorySee omnystudio.com/listener for privacy information.

Have Democrats ceded leadership in space policy? That’s what Mary Guenther believes. She’s the Director of Space Policy at the Progressive Policy Institute and the author of an editorial that claims Democrats have ceded their leadership. She traces the party’s arc from Obama-era reforms to recent data showing that Democrats introduced a third fewer space bills than Republicans in recent years, and proposes ways that the party should embrace this forward-looking field while tying it to their core issues of job creation, supply chains, and climate science.See omnystudio.com/listener for privacy information.

Recorded at the 2025 Humans to the Moon and Mars Summit (H2M2) in Washington, D.C., this episode features two powerful conversations about the future of human space exploration. Hosted by Mat Kaplan, senior communications adviser at The Planetary Society, these panel discussions explore the scientific and diplomatic foundations guiding humanity’s journey beyond Earth. The first panel, Space Science: A Vital National Interest, features James Green, former NASA chief scientist and chair of the Explore Mars advisory board, James Garvin, chief scientist at NASA Goddard Space Flight Center, Britney Schmidt, astrobiologist and associate professor at Cornell University, and John Mather, Nobel Prize–winning astrophysicist and senior scientist for the James Webb Space Telescope. They discuss how space science drives innovation, strengthens U.S. national priorities, and deepens our understanding of the universe, especially in the face of proposed funding cuts. In the second panel, Artemis Accords: International Collaboration in Deep Space, Mike Gold of Redwire, Marc Jochemich of the German Aerospace Center (DLR), Adnan Mohammad Alrais of the Mohammed bin Rashid Space Centre, and Sohair Salam Saber of The Hague Institute for Global Justice explore how diplomacy and shared values are shaping global participation in lunar exploration. The conversation also highlights the Washington Compact, an effort to bring shared values and responsible behavior in space to commercial companies and other non-governmental organizations. We wrap up the show with a new What’s Up segment with Bruce Betts, where we talk about what could happen if the Gateway lunar space station is canceled, and how that would impact humanity’s dreams for Mars. Discover more at: https://www.planetary.org/planetary-radio/2025-H2M2See omnystudio.com/listener for privacy information.

Alicia Brown from the Commercial Space Federation and Brittany Webster from the American Geophysical Union join the show to discuss NASA’s fiscal year 2026 budget proposal, which aims to slash the agency’s funding by nearly 25%, cut science by 47%, and reduce staffing to levels not seen since 1960. Discover more at: https://www.planetary.org/planetary-radio/fy2026-nasa-budget-discussionSee omnystudio.com/listener for privacy information.

The Giant Magellan Telescope (GMT) is poised to become one of the most powerful ground-based observatories ever built. On June 12, 2025, the U.S. National Science Foundation announced that the GMT will enter its Major Facilities Final Design Phase, bringing it one step closer to full construction. This week on Planetary Radio, host Sarah Al-Ahmed speaks with Rebecca Bernstein, Chief Scientist for the Giant Magellan Telescope Organization and astronomer at the Carnegie Institution for Science, about the groundbreaking technology behind GMT and how it will transform our understanding of the Cosmos. Later in the show, Casey Dreier, chief of space policy at The Planetary Society, returns to discuss his new op-ed in Space News on the White House’s controversial Mars plan, and why a bold vision without political consensus is unlikely to succeed. As always, we wrap up with What’s Up with Bruce Betts, chief scientist at The Planetary Society. Discover more at: https://www.planetary.org/planetary-radio/2025-gmtSee omnystudio.com/listener for privacy information.

Few writers have captured the wonder of science through storytelling as powerfully as Dava Sobel. In this episode, we celebrate her remarkable career and her recent honor as the recipient of The Planetary Society’s 2025 Cosmos Award for Outstanding Public Presentation of Science. Mat Kaplan, senior communications advisor at The Planetary Society, sits down with Sobel for a conversation about the human lives behind great scientific discoveries, from Galileo and Copernicus to the women of the Harvard Observatory and Marie Curie’s lab.  Later in the show, Jack Kiraly, our director of government relations, joins us with an encouraging update on our public advocacy campaign to save NASA science. And don’t miss What’s Up with Bruce Betts, where we reflect on the role of science communicators and share a fresh Random Space Fact. Discover more at: https://www.planetary.org/planetary-radio/2025-cosmos-awardSee omnystudio.com/listener for privacy information.

What does it take to turn a love of space into a global career in science journalism? Sarah Cruddas has done just that. With a background in astrophysics and a passion for storytelling, she’s become a leading voice in space media, covering rocket launches, interviewing astronauts, and writing books that bring the Cosmos down to Earth. In this episode, Sarah shares her path from the U.K. to the front lines of space communication and why she believes storytelling is essential to the future of exploration. She also reflects on the challenges of breaking into the field, the power of listening, and how space can unite people across the globe. Plus, Bruce Betts joins us for What’s Up, where we talk about what makes a great space journalist. Discover more at: https://www.planetary.org/planetary-radio/2025-making-space-matterSee omnystudio.com/listener for privacy information.