Extend this unit's false-positive and extremophile-limit reasoning.
Earth's atmospheric methane has a chemical residence time of roughly a decade. Using the disequilibrium argument from Lecture 11, explain what this short residence time implies about the source of Earth's atmospheric methane, and contrast this with a hypothetical planet where methane is detected but has a residence time of a billion years.
A newly characterized rocky planet orbiting an active M-dwarf, well inside the star's pre-main-sequence-inflated early habitable zone, shows a strong O2 feature but no detectable water vapor, methane, or other reduced gases. Using Lecture 11's reasoning, state whether this pattern is more consistent with a biological or an abiotic origin, and justify your answer.
Using the distinction from Lecture 12, explain why "tardigrades survive 600 MPa" is not equivalent evidence to "some organism can actively grow and reproduce at 600 MPa," and why this distinction matters for interpreting a hypothetical high-pressure subsurface-ocean-world biosignature claim.
Explain why an organism like Chroococcidiopsis, which tolerates extreme desiccation, high UV flux, and large temperature swings simultaneously, is considered a more astrobiologically relevant analog for a Mars-surface or an icy-moon-surface environment than an organism documented to tolerate only one of those extremes in isolation.
Submit a complete derivation with equations, units, labeled quantities, and a short narrative interpretation for each problem. Show every step; a correct final number without a visible derivation receives partial credit at most, and quoting a lecture number without adapting it to this problem's specific inputs receives no credit for that step.
OpenStax Astronomy 2e (local extracted reference copy: references/openstax-astronomy-2e-extracted.txt) introduces exoplanet detection methods in the "Exoplanets" section of Chapter 7 (Other Worlds: An Introduction to the Solar System) and astrobiology topics (habitable zone, biosignatures, the Drake equation) in Chapter 30 (Life in the Universe); these citations follow the ASTR320/330 precedent of using native OpenStax chapter numbering, extrapolated by analogy rather than independently cross-checked against embedded figure/table numbering this session -- flagged for human spot-check in reference-log.md. Nearly every quantitative derivation in this course (the radial-velocity semi-amplitude equation, transit depth/duration, the mass-radius interior degeneracy, the radiative-equilibrium habitable-zone boundary, and the Drake equation as a structured estimation framework) goes well beyond OpenStax Astronomy 2e’s introductory, descriptive treatment; each lecture states explicitly where this course extends beyond the assigned reading.
materials/ASTR350/data/ where referenced above.