Stardust-NExT Encounters Comet Tempel 1

Episode Summary

Executive Summary: This episode centers on Stardust Next’s successful flyby of Comet Tempel 1, comparing it with Deep Impact, Hartley 2, and Wild 2 to show comets are diverse and evolving. It also includes Bill Nye on STS-133 and the Planetary Society’s upcoming Phobos experiment, plus Bruce Betts’ skywatching, space history, and trivia segments.

Main Topics: Stardust Next flyby of Tempel 1: Jessica Sunshine and Emily Lochtawala discuss the February 14 encounter, emphasizing how the spacecraft revisited Tempel 1 and captured the Deep Impact crater plus new terrain on the comet’s unexplored side. Comparing comet diversity and evolution: The conversation contrasts Tempel 1 with Hartley 2 and Wild 2, arguing comets are not uniform 'dirty snowballs' but diverse objects shaped by formation and later evolution. Surface morphology vs. composition: Because Stardust lacked spectrometers and color instruments, the flyby focused on shapes, depressions, layering, and dust behavior rather than detailed composition, making morphology central to the science return. Bill Nye on shuttle launch and future human spaceflight: Bill Nye reports from STS-133 Discovery’s launch and reflects on NASA’s future, noting the significance of U.S. crew access to the ISS and the excitement of heavy-lift shuttle launches. Planetary Society’s Living Interplanetary Flight Experiment: Nye explains that a portion of the Society’s Phobos-bound LIFEx payload will gain flight heritage on Shuttle 134, carrying freeze-dried organisms including bacteria and tardigrades. Bruce Betts’ skywatching, history, and trivia: Betts covers Jupiter, Saturn, Venus, Venera 3’s historic Venus impact, Discovery’s shuttle record, and a trivia contest about the brightest asteroid and Discovery’s ISS visits.

Key Arguments: Comets are not all the same: observations show major differences in gas production, surface structure, and dust behavior between Tempel 1, Hartley 2, and Wild 2. Tempel 1 changed between visits, but much of its surface remained similar, suggesting localized change rather than uniform resurfacing. Hartley 2’s coma contains ice grains and strong outgassing effects, unlike Tempel 1, demonstrating contrasting comet activity levels. Stardust Next’s science value came from revisiting a known target and comparing two epochs of the same comet with earlier Deep Impact data. Without spectrometers, Stardust’s Tempel 1 flyby emphasized morphology, enabling discovery of new circular features, a large depression, and prominent layering. The shuttle launch was framed as a major milestone for human spaceflight and a platform for future experiments, including the Society’s Phobos mission payload. The Planetary Society’s Phobos experiment requires flight heritage, so the shuttle opportunity is being used to qualify its biological materials for deep-space exposure. Bruce Betts uses the sky report and trivia to connect listeners to ongoing observing opportunities and historical milestones in planetary exploration.

Data Points: Date of Tempel 1 encounter: February 14 - Stardust Next flyby of Comet Tempel 1 Previous Tempel 1 encounter: 2005 - Deep Impact hit Tempel 1 with a copper projectile Hartley 2 encounter: last November - Deep Impact EPOXI flyby compared with Tempel 1 Time between Tempel 1 flybys: 5.5 Earth years - Jessica Sunshine describes seeing Tempel 1 twice, one comet year apart Shuttle launch: STS-133 - Bill Nye discusses the Discovery launch Scheduled Shuttle 134 date: April 19 - Planned flight heritage opportunity for LIFEx LIFEx destination: Phobos - Planetary Society payload bound for a moon of Mars Comet targets in comparison: 3 comets - Tempel 1, Hartley 2, and Wild 2 are discussed across two spacecraft Discovery mission count to ISS trivia: to be determined by contest; prompt asks how many times Discovery visited ISS - Bruce Betts announces next trivia question Discovery flight number: STS-133 / 133rd shuttle flight - Bruce Betts notes the numbering coincidence Discovery orbiter flights: 39th flight - STS-133 was Discovery’s 39th mission Atlantis orbiter flights: 32 - Bruce Betts compares shuttle orbiter totals Shuttle station missions: 35 - STS-133 was the 35th shuttle mission dedicated to station assembly and maintenance Venera 3 milestone year: 1966 - First human-made object to impact another planet (Venus)

Pivotal Quotes: "It was wildly successful and really reached beyond all our expectations." — Jessica Sunshine: Assessment of the Stardust Next flyby of Tempel 1 "We now know that’s just completely wrong." — Jessica Sunshine: On the old idea that all comets are basically the same dirty snowballs "It is, of course, producing gas, mostly water and CO2, but at a much slower rate given its size than Hartley II." — Jessica Sunshine: Comparison of Tempel 1’s activity to Hartley 2

Implications: The episode shows how repeated comet visits are refining models of comet structure, activity, and evolution. It also highlights near-term opportunities for public engagement in spaceflight, from shuttle-era science payloads to citizen involvement through planetary outreach and trivia.