Apparatus and Setup
This lab works through the abiotic-oxygen false-positive decision logic (Lecture 11) for a real TRAPPIST-1 planet using this course's computed habitable-zone and equilibrium-temperature results, then builds a documented extremophile tolerance summary (Lecture 12) to bound which environments could plausibly support active microbial growth.
Materials and Data
| Organism | Trait | Value | Unit |
|---|---|---|---|
| Pyrolobus fumarii | hyperthermophile | 113.0 | degC (upper growth limit) |
| "Strain 121" | hyperthermophile | 121.0 | degC (documented survival/growth) |
| Planococcus halocryophilus | psychrophile | -25.0 | degC (lowest documented growth) |
| Deinococcus radiodurans | radioresistant | 5000.0 | Gy (acute dose, no viability loss) |
| Tardigrada (several spp.) | pressure/vacuum tolerant | 600.0 | MPa (hydrostatic pressure survived) |
| Halobacterium/Haloarchaea | halophile | 32.0 | % salinity (saturated brine) |
Procedure
- Using TRAPPIST-1b's and TRAPPIST-1c's real orbital distances and this course's computed habitable-zone inner edge (0.0227 AU), state whether either planet is a plausible candidate for the published abiotic-oxygen-buildup false-positive pathway (Lecture 11).
- State what additional atmospheric detections (context gases) would strengthen versus weaken a biosignature interpretation for an oxygen signal on either planet.
- Using the extremophile table, compute the ratio of Deinococcus radiodurans's documented radiation tolerance to the human lethal dose.
- Using TRAPPIST-1e's computed zero-albedo equilibrium temperature (Lecture 09) and the documented growth-temperature range of known life (-25 to 121 degrees C), state whether TRAPPIST-1e's temperature alone is compatible with the known growth envelope of Earth life (with the explicit caveat that equilibrium temperature is not the same as actual surface temperature, Lecture 09's pitfall).
Analysis and Uncertainty
State explicitly that a documented extremophile survival/growth record is evidence about Earth life's known tolerance envelope, not proof that a given exoplanet environment is inhabited or even habitable; this lab draws only the specific, limited conclusions its data can support.
Deliverables
- TRAPPIST-1b/c abiotic-oxygen plausibility assessment with explicit reasoning.
- Radiation-tolerance ratio calculation.
- TRAPPIST-1e temperature-envelope compatibility check with appropriate caveats.
Assessment Criteria
- Correctly applies the disequilibrium/context-gas reasoning from Lecture 11, not just a generic "life is possible/impossible" statement.
- Correct radiation-tolerance ratio arithmetic.
- Explicit statement of the equilibrium-temperature-versus-actual-surface-temperature caveat.
References and Provenance
- 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.
- Extremophile records: standard published primary literature (Blochl et al. 1997; Kashefi & Lovley 2003; Mykytczuk et al. 2013; Daly 2009; Seki & Toyoshima 1998), level 2, not independently re-verified this session; see
materials/ASTR350/reference-log.md.