Mike Brown's New Book: How I Killed Pluto and Why It Had It Coming

Episode Summary

Executive Summary: This Planetary Radio episode covers major recent space news: SpaceX’s successful Falcon 9/Dragon flight, the failed Japanese Akatsuki Venus orbit insertion, NanoSail-D’s partial failure, and SOFIA’s promise. It also features Mike Brown discussing his book and Pluto’s reclassification, plus a skywatch segment on the Geminids and a total lunar eclipse.

Main Topics: SpaceX Falcon 9/Dragon breakthrough: Elon Musk and Bill Nye discuss the first orbital flight and re-entry of SpaceX’s Dragon capsule, emphasizing its near-readiness for crewed missions and the significance of commercial spaceflight. Akatsuki’s failed Venus orbit insertion: Emily Lakdawalla explains the technical failure that prevented Japan’s Akatsuki spacecraft from entering Venus orbit, likely due to helium-line blockage and an attitude-control issue. Mike Brown’s Pluto book and planetary classification: Matt Kaplan interviews Mike Brown at his book party about How I Killed Pluto and Why It Had It Coming, including the discovery of Eris, the history of the Pluto debate, and the meaning of planet. Night sky highlights: Geminids and lunar eclipse: Bruce Betts previews the Geminid meteor shower and a total lunar eclipse visible across North America, including viewing times and observing conditions. Other mission updates: NanoSail-D and SOFIA: Bill Nye notes NASA’s NanoSail-D deployment problems and highlights SOFIA as a major airborne infrared observatory with unknown discovery potential. Space history and trivia: The show also revisits historical milestones such as Mariner 2, Apollo 17, the first Venus landing, and the Wright brothers, plus a trivia contest about Apollo parachute failures.

Key Arguments: Commercial spacecraft like SpaceX’s Dragon can already perform many crew transport functions; only targeted upgrades such as escape systems and life support remain before human flight. Akatsuki appears to have suffered two separate failures: a propulsion-pressure problem and an attitude-control rotation issue, both contributing to the missed Venus orbit insertion. Mike Brown argues that the IAU’s planet definition is imperfectly worded, but the underlying concept—eight major bodies dominating the solar system—is scientifically sound. Brown frames Pluto’s demotion as part of the broader story of solar-system discovery, not a personal defeat, and says the classification debate reflects how astronomy works conceptually rather than through strict legal definitions. Bill Nye stresses that even failed missions like NanoSail-D are valuable because they generate learning and help advance future technology. Bruce Betts emphasizes that the Geminids remain one of the year’s best meteor showers and that the total lunar eclipse is a major viewing opportunity for North America.

Data Points: Dragon capsule acceleration: up to 4.5 G - Elon Musk says a crew in Dragon would have experienced about this much force during the flight. Akatsuki thruster burn duration: about 2.5 minutes - The Venus orbiter needed a 12-minute burn but fired only briefly before failing. Akatsuki required orbit insertion burn: 12 minutes - The spacecraft needed this thruster firing to enter Venus orbit. Akatsuki return time to Venus: about 6 years - After missing orbit, the spacecraft entered solar orbit and won’t return to Venus for years. NanoSail-D orbit altitude: 400 nautical miles - Bill Nye describes the drag-sail test spacecraft operating at this altitude. SOFIA flight altitude: 41,000 feet - The airborne observatory flies above most atmospheric water vapor to observe in infrared. Geminid peak rate: up to 100 meteors per hour - Bruce Betts cites this as the shower’s traditional best-case rate under dark skies. Lunar eclipse start time: 6:32 UT - Bruce Betts gives the start of the partial eclipse. Lunar eclipse totality duration: about 1 hour - The eclipse reaches totality roughly an hour after partial begins and lasts around an hour total. Falcon 9 capsule parachutes: 3 parachutes - Bruce Betts mentions Dragon’s three-chute splashdown system. Apollo parachute diameter: 25.5 meters - Compared by Bruce Betts to Dragon’s larger parachutes. Dragon parachute diameter: 35.4 meters - Bruce Betts notes the size of each Dragon parachute.

Pivotal Quotes: "If there'd been people sitting in the Dragon capsule today, they would have had a very nice ride." — Elon Musk: Post-flight remarks after SpaceX’s successful Dragon orbital test and splashdown. "It looks like it's been pretty bad news, actually." — Emily Lakdawalla: Her assessment of Akatsuki’s failed Venus orbit insertion after reviewing the early technical reports. "The concept that they tried to codify in that definition is the right concept." — Mike Brown: Brown’s explanation of why he accepts the spirit of the IAU planet definition even though the wording is flawed.

Implications: The episode highlights a turning point for commercial launch capability, the risks of planetary exploration, and the ongoing evolution of how scientists classify worlds. Listeners get both immediate skywatching guidance and a broader view of spaceflight progress and setbacks.