Looking for E.T.'s Laser Beam: An Optical SETI Update

Episode Summary

Executive Summary: This episode of Planetary Radio covers three major space stories: a sample-return update from Japan’s Hayabusa mission to asteroid Itokawa, a NASA/industry breakthrough in throttling a cryogenic rocket engine, and advances in optical SETI at Harvard using upgraded detector chips. The show closes with Bruce Betts’ night-sky guide, space history, trivia, and listener contest results.

Main Topics: Hayabusa and asteroid Itokawa sample return (Priority: 5/5): Emily Lakdawalla reports on the Hayabusa capsule’s return from Itokawa, the careful clean-room opening, and the discovery of tiny particles that may be asteroid material, though contamination checks are still needed. Cryogenic rocket engine throttling breakthrough (Priority: 5/5): Bill Nye explains a Pratt & Whitney Rocketdyne CECE engine test that dramatically improves deep throttling, comparing it to a dimmer switch and emphasizing safer, cheaper human-rated spaceflight. Optical SETI and laser-based alien signaling (Priority: 5/5): Paul Horowitz and Curtis Mead discuss searching for extraterrestrial intelligence using brief optical flashes instead of radio, enabled by a clever FPGA-based upgrade that greatly improves detector capability. Detector hardware and instrumentation advances (Priority: 4/5): The conversation details the new chip architecture, custom circuit boards, and the engineering challenge of building a camera system that can preserve full-flash context and better discriminate real signals from atmospheric events. Night sky report and space trivia (Priority: 3/5): Bruce Betts provides observing tips for planets in the evening sky, notes space history milestones, gives contest answers, and introduces a new trivia question for listeners. Planetary Society mission and membership appeal (Priority: 2/5): A brief promotional segment highlights the Planetary Society’s work, its public-facing projects, and membership benefits tied to supporting exploration and SETI efforts.

Key Arguments: The Hayabusa capsule’s apparent cleanliness is encouraging because it suggests low contamination, but definitive identification of asteroid particles requires careful chemical analysis. Optical SETI is a plausible alternative to radio SETI because modern lasers and large telescopes can produce detectable flashes that may be bright enough to stand out across interstellar distances. Upgrading the detector with an FPGA and improved buffering makes it possible to retain the full shape and timing of candidate flashes, which helps distinguish extraterrestrial signals from atmospheric Cherenkov events. Deep-throttling rocket engines is a major enabling technology for future crewed exploration because it improves control, safety, and mission flexibility. The Planetary Society’s projects depend on public support and membership, which fund outreach, exploration, and search efforts like optical SETI.

Data Points: Potential chip improvement: 16 times more capable - Curtis Mead’s FPGA-based improvement over the previous custom chip in the optical SETI system Laser flash brightness advantage: About 10,000 times brighter than our star appears to a target civilization - Horowitz explaining a possible outgoing optical SETI signal using Earth-based lasers and a large telescope Throttle range of CECE engine: 18 to 1 - Bill Nye describing how low the Pratt & Whitney Rocketdyne cryogenic engine can throttle compared with full power Old lunar module throttle range: 8 to 1 - Bill Nye comparing the CECE result with Apollo Lunar Excursion Module capability Sample-return particles found: A few very tiny microscopic particles - Emily Lakdawalla describing what was seen inside the Hayabusa capsule Estimated cost of prototype boards: About $7,200 - Horowitz discussing the price of producing three prototype boards with partial stuffing Mirror cost of optical SETI telescope: About $50,000 - Horowitz describing the bargain price of the large reflecting telescope used for the survey Flash event duration: A few nanoseconds - Horowitz describing candidate optical SETI events observed by the telescope Human population in space: 518 humans from 38 countries - Bruce Betts citing the number of people who have gone to space using the 62-mile/100-km standard Continuous human presence record: Not specified in the transcript - Bruce Betts poses a trivia question about the longest continuous period of human presence in space Crab Nebula size: Roughly 11 light years along the longest axis - Contest answer discussed by Bruce Betts and listeners Space history milestone: 1965, 1969, 1975 - Bruce Betts mentions Mariner 4’s Mars flyby, Apollo 11 launch, and Apollo-Soyuz launch/docking Trivia deadline: July 19 at 2 p.m. Pacific Time - Deadline for entering the Planetary Radio contest

Pivotal Quotes: "We have found a few very tiny microscopic particles inside the sample canister" — Emily Lakdawalla: Her report on the early inspection of the Hayabusa/Itokawa sample capsule "This is an engine, a rocket engine, with a dimmer switch." — Bill Nye: Explaining why the new CECE engine’s deep throttling matters for future missions "It’s about time, you know? I mean, here we are on Earth... and it’s about time that we joined the club." — Paul Horowitz: His argument for pursuing optical SETI and the possibility of a galactic civilization

Implications: The episode highlights how incremental engineering gains—from sample-return handling to engine throttling and detector chips—can unlock major scientific and exploration advances, while also showing how public support sustains high-risk frontier work.