High Flyin', Cave Divin' Planetary Science with Dan Durda

Episode Summary

Executive Summary: This Planetary Radio episode blends outreach, science, and updates from the Planetary Society. Dan Durda discusses near-Earth object surveys, the Shoemaker NEO Grant Program, impact experiments on meteorites, airborne occultation work, volcanoid searches, cave-diving-inspired astrobiology, and astronomical art. Bruce Betts closes with skywatching, Mars’ approach, a Venus trivia challenge, and a note on space transportation policy.

Main Topics: Shoemaker Near-Earth Object Grant Program: Durda explains how Planetary Society funding supports amateur and professional follow-up observations of near-Earth objects, helping refine orbits and physical characteristics of asteroids and comet remnants. Impact physics and meteorite disruption experiments: He describes firing pellets at real meteorite samples at NASA Ames to study how asteroidal material breaks apart and produces interplanetary dust, improving understanding beyond using terrestrial analog rocks. Airborne astronomy in F-18 jets: Durda and colleagues use a compact camera setup in an F-18 to observe asteroid occultations above clouds and over oceans, and to pursue searches for elusive inner-solar-system volcanoids. Volcanoids and Mercury’s historical mystery: The discussion traces the origin of the volcanoid search to the old anomaly in Mercury’s orbit, the proposed planet Vulcan, and how Einstein’s relativity resolved the orbital discrepancy while leaving room for possible debris populations. Cave diving, robots, and Europa analog research: Durda connects cave-diving experience in Arizona and Florida to developing autonomous underwater robots for mapping hot springs and searching for life, with direct relevance to Europa’s suspected ocean environment. Astronomical art and public engagement: He notes his membership in the International Association of Astronomical Artists and his science-art work, including a widely seen New Horizons/Pluto painting, showing the overlap between research and communication. Skywatching, trivia, and society updates: Bruce Betts covers visible planets, Mars’ rapidly improving visibility before its close approach, a Pluto distance analogy, a Venus trivia question, and a space transportation workshop recommendation.

Key Arguments: The Shoemaker NEO Grant Program fills a critical gap by funding follow-up and physical characterization work that large survey programs often lack time and money to perform. Amateur astronomers are often doing professional-quality science, and some have built impressive facilities that rival those used by professionals. More follow-up observations improve orbital precision, which is essential for predicting future close approaches and impact risk. Using real meteorites rather than terrestrial substitutes yields better insight into how asteroids actually fragment and generate dust. Airborne observations from a fighter jet can overcome cloud cover and twilight limitations, enabling occultation measurements and inner-solar-system searches impossible from the ground. A search for volcanoids remains scientifically worthwhile despite past null results because the search has been limited and the population could still exist. Cave-diving expertise can be repurposed into astrobiology tools for Europa-like environments, especially autonomous systems for inaccessible subsurface habitats. Scientific art serves as both a personal outlet and a public communication tool, reinforcing outreach around missions like New Horizons.

Data Points: Year the Shoemaker NEO Grant Program started: 1997 - Founded by the Planetary Society to honor Gene Shoemaker and support NEO work Estimated number of objects larger than 1 km near Earth: about 1,100 - Durda cites the expected population of large near-Earth objects Completion of NASA goal to find 90% of large NEOs: goal set about a decade earlier; ~60% found at time of interview - He says surveys have identified roughly 60% of expected objects Telescope diameter mentioned: 8-inch telescope - Matt Kaplan mentions his own small home telescope as an example of accessible astronomy Timeframe of asteroid occultation work: back in 2000 - Durda says they timed a successful occultation of an asteroid called Palixo Altitude platform: F-18 fighter jet - Used for airborne astronomy and occultation searches Targeting of volcanoids: inside Mercury’s orbit - Searches focus on very small bodies close to the Sun Date of Gemini 4 launch: June 3, 1965 - Bruce Betts’ space history segment Closest Mars approach reference: August 27 - Mars was said to be closest to Earth in 73,000 years Mars proximity comparison: 73,000 years - Betts notes the upcoming close approach was the closest in this span Pluto distance analogy: ~40 times Earth-Sun distance - Random Space Fact about Pluto’s average distance from the Sun Mars trivia prize: Mars 3D poster - Awarded to weekly trivia winner Answer to Tethys nomenclature question: People and places from Homer's Odyssey - Bruce Betts reveals the previous week’s answer

Pivotal Quotes: "The real goal, the intent of the Shoemaker NEO Grant Program is to increase... the rate of discovery and follow-up observations of the near-Earth objects that are passing near our planet." — Dan Durda: Explaining the purpose of the Planetary Society grant program "some of these quote-unquote amateurs have facilities and instrumentation that is making some of the professionals drool" — Dan Durda: Describing the high quality of amateur contributions to NEO follow-up work "The moon Europa may have a pretty deep subsurface ocean under that crust of ice, and at the bottom of that ocean may be possibly thermal vents and so on" — Dan Durda: Linking cave-diving robotics to future astrobiology on Europa

Implications: The episode underscores how modest funding, amateur participation, and creative observing platforms can materially improve planetary defense, asteroid science, and astrobiology. It also shows how outreach, art, and trivia help translate complex research into public engagement.