The Envelope Please: Choosing the 2007 Mars Scout Mission, Part 1

Episode Summary

Executive Summary: Planetary Radio centers on NASA’s upcoming 2007 Mars Scout selection, featuring Peter Smith’s Phoenix lander and Lori Leshin’s SCIM sample-return flythrough concept. The episode explains their science goals, cost-saving heritage, and mission design, then shifts to Mars, comets, and a trivia segment from Bruce Betts. It also highlights outreach, public engagement, and the competitive stakes for the finalist teams.

Main Topics: NASA Mars Scout finalist competition: The show frames the episode around the impending NASA decision on the 2007 Mars Scout mission and introduces the four finalist teams, with focus on Phoenix and SCIM. Phoenix Mars Lander proposal: Peter Smith explains Phoenix as a reborn mission using cancelled lander hardware and instruments to investigate water-ice-rich soil in Mars’ northern plains. SCIM sample-return flythrough mission: Lori Leshin describes SCIM as a radical, low-cost concept that skims Mars’ atmosphere to collect dust and gas for return to Earth. Comets and the Oort cloud: The Q&A segment explains why long-period comets arrive from all directions: the Oort cloud is loosely bound and perturbed by passing stars. Mars observing and space trivia: Bruce Betts provides Mars viewing advice, a brief space-history note, a random fact about Mars time, and a weekly trivia contest. Planetary Society outreach and education: The episode includes a membership pitch, emphasizes public participation, and notes educational partnerships, including with the Planetary Society.

Key Arguments: Phoenix is cost-effective because it reuses hardware and instruments from cancelled Mars missions, allowing a faster build and test cycle. Phoenix targets Mars’ northern plains because orbital data indicate subsurface water ice is likely present there. Phoenix’s science is designed to assess habitability by analyzing soil chemistry, salinity, oxidation, metals, and organics after adding water and heating samples. SCIM argues that flying through the atmosphere and returning samples is a much cheaper way to get Martian material to Earth than a full surface sample-return mission. SCIM is modeled on Stardust-style aerogel capture and aims to exploit the dustiest season and region of Mars to maximize sample collection. The Oort cloud explanation emphasizes that distant objects are weakly bound to the Sun, so stellar perturbations can send comets inward from many directions. Mars rover operations must run on Mars time, which is scientifically necessary but difficult for mission staff on Earth.

Data Points: Mars Scout finalists: 4 - NASA’s 2007 Mars Scout selection included four finalist teams. Phoenix heritage missions: Mars Polar Lander and O-1 lander - Phoenix reuses components from previously cancelled missions. Water-ice target depth: about a foot or two - Phoenix expects to trench down to icy layers beneath the surface. Mars Reconnaissance Orbiter camera resolution: 30 centimeters per pixel - Smith cites the planned orbiter’s high-resolution imaging. TIGA oven temperature: up to 950 degrees - Phoenix will heat soil samples to analyze released gases and organics. Organic detection threshold: above about 300 degrees - Phoenix can drive off organics from ice-rich soil at this temperature range. SCIM atmospheric transit time: about 5 minutes - Leshin describes the full atmospheric encounter duration. SCIM dust plume time: about 100 seconds - The briefest part of the flythrough where sample capture occurs. SCIM speed: about 14,000 miles an hour - The probe will pass through Mars’ atmosphere very rapidly. Collected dust particles: millions - SCIM expects to gather millions of dust particles. Large dust particles to be analyzed: about 1,000 larger than 10 microns - These larger particles will be subdivided and studied in labs. Atmospheric gas sample volume: about a quart / 1 liter - SCIM aims to return a liter of Martian gas. Mars day length: 24 hours and 38 minutes - Bruce Betts gives the duration of a Martian sol. Oort cloud distance: 50,000 times farther from the Sun than Earth - Used to explain why long-period comets can arrive from all directions. Oort cloud scale: nearly a light-year away - The Q&A notes the cloud’s extreme distance. Women in science: about 20% - Leshin discusses representation in science. Women in engineering: about 9% - Leshin cites this as still lagging despite progress. Apollo-Soyuz splashdown date: July 24, 1975 - Bruce Betts answers the previous trivia question. Mariner 6 flyby year: 1969 - Space-history note in the Bruce Betts segment. Apollo 15 lunar rover year: 1971 - Space-history note in the Bruce Betts segment.

Pivotal Quotes: "We called it Phoenix because it's reborn out of the canceled missions of the past." — Peter Smith: Explaining the naming and heritage of the Phoenix Mars lander proposal. "We skim the atmosphere of Mars, collecting dust and gas as we go and coming out the other side and bringing those samples back to Earth." — Lori Leshin: Describing the core SCIM mission concept. "The answer has to do with the great distance of Oort cloud objects from the Sun." — Emily Lochdawala: Introducing the explanation for why long-period comets come from all directions.

Implications: The episode shows NASA favoring lower-cost, high-heritage mission concepts while underscoring Mars as a continuing focus for astrobiology. It also illustrates how sample return, even via unconventional methods, remains a major scientific priority.