Looking Back at the Phoenix Mars Polar Lander With Peter Smith

Episode Summary

Executive Summary: This episode centers on Phoenix’s Mars mission postmortem with PI Peter Smith, highlighting unexpected perchlorate in soil, widespread near-surface water ice, and evidence of snow and weather processes at the landing site. The show also covers the Spirit rover’s 5th anniversary, orbital advances in Mars site selection, a night-sky update, and space trivia.

Main Topics: Phoenix mission postmortem: Peter Smith reviews Phoenix’s successful but finite mission and explains that the science phase ended, while data analysis is only beginning. Unexpected perchlorate discovery: The biggest surprise from Phoenix was finding perchlorate in Martian soil, which has major implications for chemistry, habitability, and organic detection. Water ice, snow, and polar climate: The mission confirmed near-surface ice, observed multiple ice expressions, and detected snow and cloud-related water processes at the polar site. Life potential and habitability: Smith discusses how habitability depends on liquid water and how Phoenix’s results challenge previous Mars weather models and refine the search for life. Mission operations and team structure: Phoenix’s operations were run from the University of Arizona, demonstrating a successful distributed mission model involving students and JPL engineers. Mars rover anniversary and orbital progress: Bill Nye previews a 5th anniversary event for Spirit and Opportunity, while Emily explains how improved orbital data changed expectations for rover landing sites. Night sky and trivia segment: Bruce Betts gives a brief skywatching update, an eclipse note, a space-history fact, and a trivia question about the first chimpanzee in space.

Key Arguments: Phoenix exceeded expectations by operating longer than many anticipated and produced a large dataset that will keep scientists busy for years. The perchlorate discovery was unexpected and scientifically significant because it affects soil chemistry and may destroy organics during heating experiments. Finding water ice alone does not prove habitability; liquid water and accurate climate models are needed to assess the potential for life. Phoenix showed that Martian weather models were incomplete because they failed to predict snowfall and nightly deposition of water vapor as frost. The mission’s University of Arizona-centered operations model worked well and could serve as a precedent for future planetary missions. Improved orbital spectroscopy since Spirit and Opportunity landed means future missions can target more water-rich, geologically informative sites.

Data Points: Phoenix operational phase duration: about 5 months - Smith says the science/operations phase ended after the landing, with analysis beginning only after the mission stopped operating in early November. Expected vs actual mission length: 2 months longer than many expected - The host notes Phoenix lasted longer than predicted for a polar lander mission. Perchlorate abundance: as high as 1% of the soil - Smith cites chemists’ estimate of perchlorate concentration in Martian soil. Martian axial tilt threshold: about 30 degrees - Smith explains that when Mars’ tilt exceeds this level, polar cap stability changes and more water can enter the atmosphere. Current Martian tilt: 25 degrees - Used to explain that Mars is currently below the threshold where the polar cap becomes unstable. Robotic arm length: 7.5 to 8 feet - Describes Phoenix’s limited reach and the small area it could directly sample. Students supporting operations: 25 to 30 - The University of Arizona hosted students who helped support Phoenix operations in Tucson. Data volume from one camera: 30,000 pictures - Smith notes the large amount of imagery still needing analysis. Spirit rover anniversary: 5 years - Bill Nye promotes a public event celebrating Spirit and Opportunity’s fifth anniversary. Annular solar eclipse date: January 26 - Bruce Betts gives the eclipse date during the skywatch segment. Trivia answer: glass type: Corning Pyrex - The Palomar 200-inch mirror material is discussed as the correct answer to the prior contest. Contest deadline: January 12, 2009 at 2 p.m. Pacific - Deadline for entering the new trivia contest.

Pivotal Quotes: "the thing that surprised me most was a totally unexpected discovery of perchlorate in the soil" — Peter Smith: On the most surprising Phoenix finding "we think of this period of the mission right now as the sleeping beauty mode" — Peter Smith: On the possibility of Phoenix reawakening in Martian spring "it worked extremely well" — Peter Smith: Describing the University of Arizona operations model

Implications: Phoenix reshaped understanding of Mars’ polar chemistry and climate, improved the search for habitable environments, and showed that university-led operations can successfully run planetary missions while setting up years of follow-up analysis.