Chasing New Horizons to Pluto with Alan Stern and David Grinspoon

Episode Summary

Executive Summary: The episode covers two major space exploration stories: Emily Lakdawalla’s updates on Mercury, Juno, and China’s Chang’e 4 relay orbiter, and a deep interview with Alan Stern and David Grinspoon about their book on New Horizons and Pluto. The New Horizons segment emphasizes the mission’s long political, technical, and human struggle, its near-failure at the July 4, 2015 flyby, and the team’s eventual triumph.

Main Topics: Mercury science and the BepiColombo mission: Emily Lakdawalla explains why Mercury is so difficult to reach, what MESSENGER taught us, and how BepiColombo’s dual-orbiter design will extend Mercury science globally. Mercury’s water ice and planetary evolution: The discussion highlights water ice at Mercury’s poles, evidence for a large liquid outer core, planetary shrinkage, and volcanic history, plus open questions that remain after MESSENGER. JunoCam image montage and public visualization: A community-made montage of JunoCam images is praised as a valuable way to review the mission’s data and choose targets for deeper exploration. Chang’e 4 relay orbiter and far-side lunar communications: China’s Chichao relay orbiter is described as a communications bridge for the future Chang’e 4 far-side lander, with launch and insertion timelines discussed. The struggle to get New Horizons to Pluto: Alan Stern and David Grinspoon recount the decades-long battle for mission approval, funding, institutional support, and spacecraft development under severe constraints. Clyde Tombaugh, mission symbolism, and public engagement: The book and mission honor Pluto’s discoverer with a symbolic payload of ashes and a canceled stamp, underscoring the emotional and historical continuity of exploration. New Horizons’ 2015 crisis and recovery: The interview details the July 4, 2015 spacecraft reboot and loss of flyby files, and how the small team rebuilt and reloaded critical instructions in time for the encounter.

Key Arguments: Mercury is extraordinarily hard to orbit because spacecraft must shed speed deep in the Sun’s gravity well; this makes getting there nearly as difficult as getting to Pluto. MESSENGER revealed major Mercury discoveries, including planetary shrinkage, a liquid outer core, volcanic history, and polar water ice, but only mapped the northern hemisphere in detail. BepiColombo’s paired spacecraft architecture will enable global, complementary science: one focused on the magnetosphere/exosphere and the other on geology/topography. New Horizons succeeded not just because of engineering but because of sustained public advocacy, institutional persistence, and a small, highly committed team. The mission’s approval depended on competition between institutions and political support, showing how planetary exploration often advances through rivalry and advocacy as much as science. The July 4, 2015 anomaly showed the importance of autonomy and mission operations expertise: the spacecraft survived because the team could reconstruct lost instructions rapidly. The book deliberately focuses on the human and programmatic story rather than the science results, which are treated only briefly because the mission narrative itself is the central achievement.

Data Points: Mercury missions: Third mission ever to visit Mercury - Emily describes BepiColombo as the next major Mercury mission after Mariner 10 and MESSENGER BepiColombo spacecraft: 2 spacecraft - A European orbiter and a Japanese orbiter will enter separate Mercury orbits Travel time to Mercury: Nearly a decade - The mission will take almost ten years to reach Mercury Mercury shrinkage: 7–8 kilometers - MESSENGER results discussed at the Mercury meeting Mercury volcanic activity: ~3.5+ billion years ago - Major volcanic activity on Mercury is described as very old New Horizons team size: 50 people - Alan compares New Horizons to Voyager’s much larger team Voyager team size: Close to 500 people - Used as a contrast to the small New Horizons team Mission duration before flyby: 15 years - Team members were asked to commit for the life of the project Launch date: Friday, January 13, 2006 - The day the RTG was fueled and the spacecraft was photographed before launch Pluto flyby date: July 2015 - The episode recounts the flyby encounter and crisis Closest-approach crisis timing: 10 days before closest approach - The spacecraft lost contact shortly before the Pluto encounter Light-time delay to Pluto: 4.5 hours one way / 9 hours round trip - Explains why the spacecraft had to be autonomous Targeting timeline: 3 days before the core encounter - The reboot occurred just before crucial science observations began New Horizons next target: Ultima Thule (Ultima Thule/Ultimate Thule as spoken in transcript) - The team looks ahead to a New Year’s Eve/New Year’s Day flyby Chang’e 4 timing: December 2018 or early 2019 - Potential delay for the far-side lunar lander launch Phoenix Mars landing anniversary: 10 years - Bruce Betts notes the anniversary in the trivia segment Phoenix landing latitude: 68 degrees north - Highest-latitude successful Mars lander mentioned Failed Mars Polar Lander latitude: 76 degrees south - Used for comparison with Phoenix Juno imagery compilation: 11 perijoves - Referenced in the Planetary Society blog item

Pivotal Quotes: "We weren't trying to scare anybody off, but we did want to tell people what it's really like because that's kind of an untold story." — Alan Stern: Explaining why the book emphasizes the difficulty of proposing and flying planetary missions "If Pluto mission had been a cat, it would have been dead long ago because cats only get nine chances." — Alan Stern: Describing how many times the mission nearly failed before launch "make us proud." — Alan Stern: His private farewell to New Horizons before launch

Implications: The episode shows that major planetary missions depend on persistence, public support, and small teams of highly skilled people. It also previews ongoing exploration at Mercury, the Moon, and the Kuiper Belt, while reminding listeners that mission history is often as dramatic as the science itself.