Off to Pluto and Its Three Moons with Alan Stern

Episode Summary

Executive Summary: This episode centers on Pluto exploration, featuring Alan Stern on New Horizons’ imminent launch and the discovery of two new Pluto moons, plus implications for Pluto’s system and the Kuiper Belt. The show also explains how Apollo rocket launch footage was captured, gives a sky update from Bruce Betts, and wraps with trivia about parsecs and space history.

Main Topics: New Horizons mission to Pluto: Alan Stern outlines the spacecraft’s preparation, launch window, speed, and extended mission beyond Pluto into the Kuiper Belt. Discovery of two new Pluto moons: Stern discusses the Hubble-based discovery of S/2005 P1 and P2, why they likely are moons, and how they may help explain Pluto’s system evolution. Possible Pluto rings and orbital resonances: The new moons may act as debris sources and imply Pluto could have rings, which New Horizons may be able to detect. Apollo rocket footage and launch imaging: Emily Lakdawalla explains that Apollo stage-separation film came from ejected 16mm cameras, and compares that with modern rocket-cam technology. Night sky update and solar system trivia: Bruce Betts provides observing tips for Mars, Venus, Saturn, Jupiter, and the Geminids, plus a trivia contest on parsecs and a space-history note about Mars 2. Kuiper Belt science and solar system formation: Stern frames the Kuiper Belt as a region preserving planetary embryos and early formation processes, making it scientifically important for understanding solar system origins.

Key Arguments: New Horizons was designed as a fast flyby with unusually long science coverage; Stern says it will function as a "five-month encounter" rather than a brief pass. The two newly found Pluto satellites are strong candidates for real moons because their positions match predicted orbital paths and earlier Hubble data. The satellites may be related to the event that formed Charon and could help explain how the Pluto-Charon system evolved. Small moons in a heavily bombarded environment could source debris that forms rings around Pluto, making rings plausible even if hard to see from Earth. The Kuiper Belt preserves bodies that stalled during planet formation, so New Horizons can probe early solar system growth stages. Modern launch cameras are now routine and far less heroic than Apollo-era recovery cameras, but the purpose remains the same: diagnosing launch events and capturing imagery.

Data Points: New Horizons travel time to Pluto: about 9 years - Stern says the fastest launch profile can reach Pluto in nine years if launched early in the window. Distance to Pluto: about 6 billion miles - Described as the target distance for New Horizons. Hubble observation time to discover moons: 8 minutes - Hubble detected one new satellite on May 15 and confirmed both on May 18 in short observations. Potential size of larger new moon: up to 100 miles across - Stern estimates the larger of the two new Pluto moons could be as large as 100 miles in diameter. Pluto brightness relative to moons: almost 10,000 times brighter - Explains why finding the moons near Pluto is difficult. Pluto separation in sky: less than 2 arc seconds - Indicates how close the moons are to Pluto from Earth’s perspective. Launch window opening: January 11 - New Horizons’ launch window opens on this date. Launch window duration: 35 days - Stern says the window closes by February 14. Moon flyby timing after launch: same day before midnight - New Horizons would pass the Moon later the day it launches. Jupiter encounter timing: 13 months - Stern notes New Horizons would reach Jupiter in 13 months flat. Apollo stage-separation camera altitude: 80 kilometers above the Atlantic Ocean - Emily Lakdawalla explains where Apollo cameras recorded stage separation. Rocket cam mass: less than 100 grams - Modern Ecliptic Enterprise rocket cams are described as very small and lightweight. Mars 2 event: 1971 - Bruce Betts notes Mars 2 became the first human-made object to hit Mars. Geminid meteor rate: 40 to 60 meteors per hour - Peak expected rate for the Geminids, though moonlight will hinder visibility. Parsecs in a light year: 0.306 parsecs - Trivia answer given by Bruce Betts; equivalent to about 3.26 light years per parsec.

Pivotal Quotes: "It’s the kind of problem we look forward to." — Alan Stern: On discovering additional moons for New Horizons to study at Pluto. "It’s a five-month encounter with the Pluto system." — Alan Stern: Explaining that New Horizons was designed for extended scientific observation, not a brief flyby. "We’re going to try." — Alan Stern: On reaching Pluto before the atmosphere fully freezes out, with uncertainty in model predictions.

Implications: New Horizons could transform Pluto from a distant point into a detailed system study, while the new moons raise the chance of rings and deeper insights into Kuiper Belt formation and planetary origins.