LightSail Prepares to Take Flight

Episode Summary

Executive Summary: This episode of Planetary Radio balances astronomy updates with a major mission announcement. Emily Lakdawalla reviews striking new Rosetta comet images and Curiosity’s continued exploration of Mars, while Matt Kaplan interviews Bill Nye, Doug Stetson, and Jason Davis about LightSail A: the Planetary Society’s first CubeSat solar-sail test flight. The show closes with Bruce Betts’ sky report and a trivia contest update.

Main Topics: Rosetta’s new comet data and images: Emily Lakdawalla discusses newly released peer-reviewed Rosetta results from Comet 67P/Churyumov-Gerasimenko, emphasizing OSIRIS camera images, unusual terrain, dunes, cliffs, and questions about the comet’s internal structure and surface activity. Curiosity’s Mars geology campaign: An update on Curiosity’s work at Pahrump Hills in Gale Crater: rover self-portrait, outcrop circling, APXS measurements, software upgrade, and plans to begin drilling into Mount Sharp materials. LightSail A announcement and mission overview: Bill Nye and later project manager Doug Stetson explain that LightSail A is the Planetary Society’s CubeSat solar-sail test flight, scheduled for launch on an Atlas V in May, with the goal of validating spacecraft systems and sail deployment. Public engagement and mission tracking: Jason Davis describes the new LightSail website and near-real-time dashboard intended to let the public follow spacecraft health, temperature, orientation, and ground track data during the mission. Bill Nye, Michael Shermer, and science outreach: A backstage conversation at Caltech ties LightSail to public science communication, Bill Nye’s book Undeniable, and the broader idea that solar sailing is a practical step toward future space travel. What’s Up: skywatching and space history: Bruce Betts gives the nightly observing forecast, notes Comet Lovejoy, Venus, Jupiter, Mars, and Saturn, and reflects on the anniversaries of Apollo 1, Challenger, and Columbia, plus the close pass of asteroid 2004 BL86.

Key Arguments: Rosetta’s newly released images are scientifically rich and reveal a comet surface more complex than expected, including steep fractured cliffs, dust-filled basins, and dune-like structures. The comet’s terrain suggests a paradox: highly porous material that nevertheless fractures coherently, implying unexpected internal strength or cohesion. Curiosity is transitioning from reconnaissance to drilling at Pahrump Hills after multiple passes, making it a geologically focused campaign on Mount Sharp materials. LightSail A is intentionally a test mission, not a true solar-sailing demonstration, because its low orbit still has too much atmospheric drag for sail pressure to dominate. Even without full solar sailing, LightSail A can validate deployment, communications, attitude behavior, and spacecraft health before the higher-altitude follow-on mission. A public dashboard and media site will help make the mission transparent and educational, letting anyone track the spacecraft as it flies. Solar sailing is presented as a meaningful, future-facing step in spaceflight, echoing ideas long associated with Carl Sagan and broader exploration goals.

Data Points: Rosetta papers released: 8 research papers - Science magazine publications on Rosetta results at Comet 67P/Churyumov-Gerasimenko Image resolution: 15 centimeters per pixel - One of the newly released OSIRIS images of the comet surface Comet porosity: 70% to 80% void space - Discussion of how the comet can appear fractured yet remain coherent Fresh snow void space comparison: 90% void space - Used as a physics analogy to compare with comet porosity LightSail A size: 3-unit CubeSat, 10 by 30 centimeters - Described as loaf-of-bread-sized spacecraft Standard CubeSat size: 10 centimeters on a side - Compared with the more basic one-unit CubeSat form Fully deployed sail area: 32 square meters - LightSail’s sail size once deployed Mission duration: A few weeks - Expected total mission life in low Earth orbit for LightSail A Sail deployment time: A few minutes - Estimated time for sail deployment after spacecraft checkout Visibility window: Several days to about a week - Time period when the deployed spacecraft should be visible from the ground Orbit decay time after deployment: About a week to 10 days - Expected time before reentry after sail deployment Launch timing: Middle of May 2015 - Planned launch window for LightSail A Follow-on mission timing: Middle of 2016 - Projected timing for LightSail B, the actual solar-sailing mission LightSail orbit altitude for true solar sailing: Above about 700 kilometers - Doug Stetson explains the altitude needed to overcome atmospheric drag Huygens Titan descent time: A little less than two and a half hours - Bruce Betts trivia answer about Huygens reaching Titan’s surface Asteroid 2004 BL86 size: About a half kilometer in diameter - Bruce Betts on the asteroid flyby Asteroid 2004 BL86 approach distance: Three lunar distances - Closest known flyby of an asteroid that large until 2027

Pivotal Quotes: "It’s the event we’ve all been waiting for." — Emily Lakdawalla: On the long-awaited release of Rosetta science papers and images "This is our opportunity for a test flight of the LightSail spacecraft." — Doug Stetson: Explaining the purpose of LightSail A "I think Carl would be proud." — Michael Shermer: On solar sailing as a realization of long-held spaceflight ideas

Implications: Listeners get both a snapshot of active planetary science and a roadmap for a landmark public-spaceflight experiment. LightSail A will validate solar-sail technology and public mission tracking, while Rosetta and Curiosity continue refining our understanding of comets and Mars.