More Planetary Radio Live With Mike Brown

Episode Summary

Executive Summary: This Planetary Radio bonus episode extends a live conversation with Mike Brown and Bill Nye about Pluto’s demotion, the search for distant solar-system bodies, and why New Horizons matters. It also includes Bill Nye’s commentary on NASA’s OSIRIS-REx asteroid sample-return mission, plus Bruce Betts’ update on space biology experiments, night-sky notes, and a trivia contest.

Main Topics: Mike Brown on Pluto and the outer solar system: Brown discusses discovering Eris and other Kuiper Belt objects, how those findings led to Pluto’s reclassification, and why the region still may hide larger bodies. New Horizons and scientific excitement: Brown explains that New Horizons is more exciting now because it will contextualize Pluto by comparing it with similar objects like Eris, Makemake, and Quaoar. OSIRIS-REx and asteroid sample return: Bill Nye frames NASA’s OSIRIS-REx mission as a way to bring back asteroid regolith for clues about the early solar system, water, and life’s origins. Audience Q&A on methane, dark matter, and telescopes: Questions cover methane-rich outer-solar-system surfaces, how spectra reveal composition, dark matter’s distribution, and the observatories used for Brown’s discoveries. High Fidelity Star Trek parody performance: The barbershop quartet returns with a comic Star Trek-themed musical parody, providing a lighter entertainment segment within the live show. Bruce Betts on shuttle-return biology experiments and skywatching: Betts reports that microbes and tardigrades returned from spaceflight experiments, then gives a brief night-sky forecast and announces a trivia question about the K-T/K-Pg boundary.

Key Arguments: Asteroid sample return is valuable because “every rock tells a story,” and returned regolith can reveal early solar-system conditions. Pluto’s demotion is scientifically useful because it led to recognizing a whole population of Pluto-like worlds rather than a lone oddball object. New Horizons is more compelling now because it will compare Pluto to multiple similar bodies, not just study a single isolated object. There may still be large unseen bodies in the outer solar system because very distant objects can evade detection if placed far enough away. Methane on outer solar-system objects can be identified through spectral fingerprints and transformed by radiation into red, sticky “goo” or tar. Dark matter can be mapped on galactic scales by tracking stellar motions, but its local effect in the solar system is too diffuse to measure directly. The shuttle-based biological experiment is a precursor to future interplanetary-life studies, including Phobos Life, and helps test whether organisms could travel between planets.

Data Points: OSIRIS-REx launch year: 2016 - Nye says the mission leaves in 2016. OSIRIS-REx return year: 2023 - Nye says the sample returns to Utah in 2023. Asteroid sample mass: about 60 grams (about 2 ounces) - Planned amount of asteroid regolith to be returned. Attendance at Planetary Radio Live: about 150 people - Live show audience in Pasadena. New Horizons launch year (as referenced in the transcript): 2005 - Brown corrects the launch timeline while discussing Pluto. New Horizons Pluto encounter year: 2015 - Brown notes the spacecraft reaches Pluto in 2015. Eris discovery timing: two weeks before New Horizons launch - Brown says Eris was discovered shortly before the launch. Universe unknown fraction: 94% - Audience question references dark matter and dark energy as the majority of the universe. Mass extinction timing: 65 million years ago - Betts references the impact event at the K-T boundary. Species lost in extinction: 70% - Betts says the event killed off 70% of species on Earth. STS-134 shuttle mission date: June 1 - Betts says the shuttle experiment returned on June 1. Organisms in shuttle experiment: millions of passengers - Betts jokes about the number of microbes/tardigrades flown on the shuttle mission. Listener deadline: June 20, 2 p.m. Pacific time - Deadline for trivia contest answers.

Pivotal Quotes: "Every rock tells a story." — Bill Nye: Commentary on why returning asteroid material matters scientifically. "I’m actually more excited now than I was when the mission was first proposed." — Mike Brown: Brown on why New Horizons feels more scientifically compelling now than at the time of proposal. "We don’t really know the answer to that very well." — Mike Brown: Brown responding to a question about dark matter and whether it affects the region between Earth and his newly discovered objects.

Implications: The episode highlights how Pluto’s reclassification expanded planetary science, why sample-return and flyby missions still matter, and how outreach blends research with humor. It also signals continued interest in outer-solar-system discoveries and astrobiology-style experiments.