Read the exposure state: INCOMING means shelter before it lands, EXPOSED means viability is draining, CLEAR means grow.
Shelter from the incoming hazard: brood for one mild threat, spore when storms stack or bite hard.
Snap back to protonema the instant it is CLEAR, to heal and grow.
Perfect Shelter: change into an adequate form right as the hazard lands for a cheaper switch and a Regrowth Bonus. Optional mastery, never required to survive.
Every shelter spends biomass. Viability and Biomass feed your Germination Forecast, so do not hide longer than you must.
Keys: 1 / 2 / 3 forms · P pause · M mute · ? hints
Physcomitrium patens is a model moss, an early-diverging land plant. The study screened three of its tissues, which differ in toughness: protonema (growing filaments) is fragile; brood cells (ABA-induced diaspores) are hardier; and the most stress-tolerant is the sporophyte holding encased spores. In the game the three forms are those tissues. Switching between them is a playable model, not something the flight sample actually did.
Detail: ploidy differs. Protonema and brood cells are haploid gametophyte tissue, the sporophyte is diploid. P. patens is a model organism partly because its genome records early land-plant stress adaptations (Rensing et al., 2008).
Question: can this moss survive prolonged, direct exposure to open space and still germinate? Hypothesis: the dormant, encased spore is the most stress-tolerant tissue, so it could endure conditions that kill growing tissue.
Detail: the hypothesis follows from the ground screens, where encased spores tolerated roughly 1,000× the UVC dose that killed brood cells (Maeng et al., 2025).
First, ground screening confirmed the encased spore was toughest, so mature sporophytes were selected to fly. UVC, −80 °C and 55 °C compared all three tissues; vacuum and VUV tested the encased spores only. The selected sporophytes were then exposed outside the ISS for 283 days. Four conditions were compared, but only three were mounted outside: station in the dark, station in filtered light with UV cut, and station in full sunlight, against a laboratory control kept dark on Earth. Only that comparison isolates ultraviolet. Day 283 ended the exposure (23 Dec 2022); the unit returned to Earth on 11 Jan 2023, and only then were spores extracted from the sporangia, sown, and scored. In the game, UV is the measured stressor; heat, cold, radiation and vacuum are combined-void / ground-screen dramatizations, not five separate ISS treatments.
Detail: screens ran UVC at 254 nm, vacuum at 4 × 10⁻⁵ torr (99% germination after 29 days) and VUV at 172 nm. The −80 °C screen compared all three tissues; a separate −196 °C test used spores only (≈9% germination after 8 days). Limitation: one species, nine months, light intensity unquantified.
Germination after return: Ground dark 97%, Space dark 95%, Space UV-cut 97%, Space full-UV 86%. Ultraviolet was the one clearly significant stressor, an 11-point drop. The other two space treatments came back essentially level with the Earth control. To the best of the authors’ knowledge this is the first reported bryophyte to survive space exposure and germinate after return. That is a first for bryophytes, not a duration record: seeds from earlier missions were exposed outside the station for 558 and 682 days. Your Germination Forecast is a simulation output, shown separately from these fixed published results.
Detail: chlorophyll a fell about 20% in both light-exposed groups, including the UV-cut one, so the paper attributes it to visible/infrared light and degradation rather than UV alone. Chlorophyll b and carotenoid changes were not significant. Limitation: the study scored germination and the resulting protonemata, not later development or reproduction.
Encased spores were the most tolerant tissue screened. Whether and how the sporangium contributed remains unresolved. Knowing which tissue survived is not the same as knowing what made it survive. Cell-wall UV-screening phenolics, DNA repair, dehydrins and heat-shock proteins are candidates the study did not demonstrate as the cause, each cited to its own moss research. The one proposal the study does make is its own, and it is hedged: the sporangium may act as a barrier, and the molecular mechanism remains unclear. Ionizing radiation is a further open question, not a finding: no radiation screen was run on these tissues at all, so the game's cosmic-ray hazard is a playable orbital model. Longer duration is needed: germination declines with exposure, and the ~5,600-day (≈15-year) figure is only where a two-point exponential fit falls to about a tenth (its decimal-reduction time, D10). It is a projection, not observed survival. Later work includes post-germination development and moss as one part of a bioregenerative life-support system.
Detail: the fit is Y = 0.9714·e−4×10⁻⁴·X (X = exposure days), anchored on only an initial reading and the nine-month point: a ~20× extrapolation beyond the observed range, which the authors themselves say to treat with caution. Two cards were deliberately left out. Trehalose: the study did not measure trehalose in the flown spores, raising the compound once as an open question and citing work in animal cells, while the published drought profile of P. patens reported proline, ascorbate and sugar alcohols instead (Erxleben et al., 2012). That is the exact scope of the omission: an evidence gap, and no claim about what moss can synthesise. A flavonoid sunscreen card: P. patens does make UV-B-induced flavonols, but only weakly. It out-tolerates Arabidopsis despite lower flavonol levels (Wolf et al., 2010), so flavonols alone do not explain it. Flavonoids are themselves phenolics, so the UV card is framed not around a different compound class but around where the screens sit: bound into the cell wall rather than free in solution.
Shortened on screen for readability. The full APA 7 reference list, with complete author lists and what each source contributed, is in docs/final-project/video-outline.md.
Maeng, C.-H., Hiwatashi, Y., Nakamura, K., Matsuda, O., Mita, H., Tomita-Yokotani, K., Yokobori, S.-I., Yamagishi, A., Kume, A., & Fujita, T. (2025). Extreme environmental tolerance and space survivability of the moss, Physcomitrium patens. iScience, 28(12), Article 113827. https://doi.org/10.1016/j.isci.2025.113827 · Primary paper: question, methods, the four conditions, results, limits, futures.
Bennett, J. (2025, November 20). Moss spores survived in space for 9 months. Science News. · News account: plain-language significance for the narration.
Rensing, S. A., et al. (2008). The Physcomitrella genome reveals evolutionary insights into the conquest of land by plants. Science, 319(5859), 64–69. https://doi.org/10.1126/science.1150646 · Why P. patens is a model moss, and early land-plant context.
De Micco, V., et al. (2023). Plant and microbial science and technology as cornerstones to Bioregenerative Life Support Systems in space. npj Microgravity, 9(1), Article 69. https://doi.org/10.1038/s41526-023-00317-9 · Realistic future direction: plants within closed-loop life support.
Tepfer, D., & Leach, S. (2017). Survival and DNA damage in plant seeds exposed for 558 and 682 days outside the International Space Station. Astrobiology, 17(3), 205–215. https://doi.org/10.1089/ast.2015.1457 · The reason this game claims only a first reported bryophyte and never a duration record: seeds were exposed far longer.
Clarke, L. J., & Robinson, S. A. (2008). Cell wall-bound ultraviolet-screening compounds explain the high ultraviolet tolerance of the Antarctic moss, Ceratodon purpureus. New Phytologist, 179(3), 776–783. https://doi.org/10.1111/j.1469-8137.2008.02499.x · Sources the Cell-wall UV screen card (candidate).
Wolf, L., Rizzini, L., Stracke, R., Ulm, R., & Rensing, S. A. (2010). The molecular and physiological responses of Physcomitrella patens to ultraviolet-B radiation. Plant Physiology, 153(3), 1123–1134. https://doi.org/10.1104/pp.110.154658 · Sources no card: it is why there is no flavonoid-sunscreen card, and why the game makes no absence claim.
Markmann-Mulisch, U., et al. (2007). Differential requirements for RAD51 in Physcomitrella patens and Arabidopsis thaliana development and DNA damage repair. The Plant Cell, 19(10), 3080–3089. https://doi.org/10.1105/tpc.107.054049 · Sources the DNA-repair card (candidate).
Saavedra, L., et al. (2006). A dehydrin gene in Physcomitrella patens is required for salt and osmotic stress tolerance. The Plant Journal, 45(2), 237–249. https://doi.org/10.1111/j.1365-313X.2005.02603.x · Sources the Dehydrin card (candidate).
Ruibal, C., et al. (2013). Recovery from heat, salt and osmotic stress in Physcomitrella patens requires a functional small heat shock protein PpHsp16.4. BMC Plant Biology, 13, 174. https://doi.org/10.1186/1471-2229-13-174 · Sources the Heat-shock protein card (candidate).
Erxleben, A., et al. (2012). Metabolite profiling of the moss Physcomitrella patens reveals evolutionary conservation of osmoprotective substances. Plant Cell Reports, 31(2), 427–436. https://doi.org/10.1007/s00299-011-1177-9 · Sources the Osmoprotectant card (candidate): what P. patens was reported to accumulate under drought. Trehalose was not among them, and the flight study did not measure it in the flown spores, hence no trehalose card.
Oliver, M. J., Velten, J., & Mishler, B. D. (2005). Desiccation tolerance in bryophytes: A reflection of the primitive strategy for plant survival in dehydrating habitats? Integrative and Comparative Biology, 45(5), 788–799. https://doi.org/10.1093/icb/45.5.788 · The broader rehydration biology behind the Return-to-growth card. The flight observation on that card is Maeng et al.'s, not this paper's.
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