Alan Stern and a Big Milestone on the Way to Pluto

Episode Summary

Executive Summary: This Planetary Radio episode covers New Horizons’ Neptune-orbit milestone on Voyager’s 25th Neptune flyby anniversary, Rosetta’s arrival at comet 67P and the start of science operations, a delayed LightSail deployment test, and Alan Stern’s Uwingu project Beam Me to Mars. It closes with Bruce Betts’ skywatching update and a radio contest.

Main Topics: New Horizons reaches Neptune’s orbit on Voyager’s anniversary: Emily Lakdawalla and Alan Stern discuss the striking coincidence that New Horizons crossed Neptune’s orbit on the 25th anniversary of Voyager 2’s Neptune flyby, framing it as a generational handoff in outer-planet exploration. Rosetta arrives at comet 67P and science begins: Alan Stern explains Rosetta’s decade-long journey, the first comet orbiter’s scientific goals, ALICE ultraviolet spectrometer measurements, and how the lander and orbiter will study the comet through its evolution. LightSail solar sail testing delay: Bill Nye reports that a planned LightSail 'day in the life' test was postponed because of recurring radio/antenna connection problems, though the team expects to retry soon. Uwingu’s Beam Me to Mars public-message project: Stern describes a fundraising and outreach campaign that lets anyone submit a message to Mars on the 50th anniversary of the first Mars mission launch, with proceeds supporting planetary grants. Planetary Radio skywatching and trivia segment: Bruce Betts reviews Mars-Saturn conjunction timing, Jupiter and Venus visibility, the Spitzer launch anniversary, and the week’s contest winner and new question. Generational continuity in planetary exploration: Across the interview, Stern emphasizes how Voyager scientists became New Horizons leaders, and how today’s postdocs may lead missions in 25 years, highlighting science as a long-term human endeavor.

Key Arguments: New Horizons’ passage through Neptune’s orbit on Voyager 2’s 25th Neptune flyby anniversary was an unplanned but meaningful coincidence, symbolizing a handoff between exploration generations. Rosetta is uniquely valuable because it is the first comet orbiter, enabling time-domain science rather than a single flyby snapshot of comet evolution. ALICE on Rosetta, though small, is scientifically powerful and will help measure comet composition, atmosphere, noble gases, and surface properties. LightSail’s key pre-deployment test had to be delayed due to persistent radio/antenna wiring issues, but the team is close to a retry. Beam Me to Mars uses the symbolic act of sending public messages to Mars to raise awareness and funding for planetary science grants. Planetary exploration depends not only on spacecraft but on scientists passing expertise from one generation to the next, from Voyager to New Horizons and beyond.

Data Points: Voyager Neptune flyby anniversary: 25th anniversary - New Horizons crossed Neptune’s orbit on the exact date of Voyager 2’s Neptune flyby anniversary. New Horizons launch age: 8.5 years - Alan Stern notes New Horizons launched eight and a half years before this interview. Rosetta flight duration: 10 years - Rosetta reached comet 67P after a decade in space. Comet landing sites announced: 5 - ESA announced five possible landing sites for Philae. ALICE instrument size: shoebox-sized - Stern describes the Rosetta UV spectrometer as small but capable. Beam Me to Mars anniversary: 50th year - Uwingu’s project marks the 50th year of Mars exploration. First Mars mission launch year: 1964 - Used as the historical reference for Beam Me to Mars. Message transit time to Mars: 15 minutes - Stern says the messages will travel at light speed and reach Mars in about 15 minutes. Uwingu grants awarded: over 20 - Stern says Uwingu Fund has already given more than 20 grants this year. Curiosity rover mass: about 900 kilograms - Bruce Betts compares Curiosity’s mass to New Horizons. New Horizons wet mass: 470 kilograms - Betts gives New Horizons’ launch wet mass. Spitzer launch year: 2003 - Betts cites the Spitzer Space Telescope’s launch in 'this week in space history'. Contest answer: cerium and palladium - The chemistry question’s correct answer, named after Ceres and Pallas.

Pivotal Quotes: "We crossed the last fence line, if you will, on the way to Pluto, the orbit of Neptune." — Alan Stern: Stern describes New Horizons crossing Neptune’s orbit on the Voyager anniversary. "This one's like dropping directly into graduate school, I'll tell you." — Alan Stern: He characterizes Rosetta’s comet target as scientifically complex and challenging. "We want to empower and engage the public like never before." — Casey Dreyer: Promoting the Planetary Society’s space advocacy effort during the mid-show sponsor message.

Implications: The episode highlights a field moving from historic flybys to sustained, multi-mission exploration, while also showing how public participation, advocacy, and small instruments can drive science, funding, and long-term mission impact.