Interplanetary Transfer of Photosynthesis: An Experimental Demonstration of A Selective Dispersal Filter in Planetary Island Biogeography

Abstract

We launched a cryptoendolithic habitat, made of a gneissic impactite inoculated with Chroococcidiopsis sp., into Earth orbit. After orbiting the Earth for 16 days, the rock entered the Earth's atmosphere and was recovered in Kazakhstan. The heat of entry ablated and heated the rock to a temperature well above the upper temperature limit for life to below the depth at which light levels are insufficient for photosynthetic organisms ( approximately 5 mm), thus killing all of its photosynthetic inhabitants. This experiment shows that atmospheric transit acts as a strong biogeographical dispersal filter to the interplanetary transfer of photosynthesis. Following atmospheric entry we found that a transparent, glassy fusion crust had formed on the outside of the rock. Re-inoculated Chroococcidiopsis grew preferentially under the fusion crust in the relatively unaltered gneiss beneath. Organisms under the fusion grew approximately twice as fast as the organisms on the control rock. Thus, the biologically destructive effects of atmospheric transit can generate entirely novel and improved endolithic habitats for organisms on the destination planetary body that survive the dispersal filter. The experiment advances our understanding of how island biogeography works on the interplanetary scale.

Space Microbiology

“…To study the mineralogical changes in the rocks, the stability of enclosed microfossils, and the survival of endolithic microorganisms during the reentry process, ESA developed the STONE facility, which is attached to the heat shield of a Russian Foton satellite (Fig. 17) (23,24,42,262). The objective was to simulate meteorite entry into the Earth's atmosphere.…”

Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond

“…In the former case, they consisted of carbonaceous microfossils of primitive prokaryotic organisms (similar to those expected on Mars (Foucher et al 2010;). For some of the samples, microorganisms (the photosynthetic endolith Chroococcidiopsis; Cockell et al 2007) were inserted in holes drilled into the rocks or, for Stone 6, placed (painted) onto the back surfaces of the rocks, away from the exposed surface and protected from the heat of entry by 2 cm of rock. The samples were embedded into the Foton heat shield as 6 cm diameter, 1 cm thick discs except for Stone 6 which was dome shaped, having an apex 2 cm thick.…”

“…STONE Regarding the STONE 6 panspermia survival test of cells of the cyanobacterium Chroococcidiopsis, inoculated into a rock at a depth of 5 mm in order to mimic an endolithic community, the heat of entry was too high for their survival (Cockell et al 2007;Foucher et al 2010) calculated that at least 5 cm of rocky protection would be necessary to shield living organisms during entry. It was thus concluded, that in the context of lithopanspermia experiment, epilithic and endolithic photosynthetic organisms would be destroyed by atmospheric transit, whereas chasmoendolithic organisms, inhabiting deep fractures might escape ablation, though the fracture might allow the heat propagation to the cyanobacteria hidden within.…”

“…It was thus concluded, that in the context of lithopanspermia experiment, epilithic and endolithic photosynthetic organisms would be destroyed by atmospheric transit, whereas chasmoendolithic organisms, inhabiting deep fractures might escape ablation, though the fracture might allow the heat propagation to the cyanobacteria hidden within. However, motile photosynthetic organisms, temporarily situated deep within a rock, might escape ablation of the surface and move back into a more favorable light regimen following interplanetary transfer (Cockell et al 2007). …”

E

“…2 Exposure tray of the ES029 experiment, which was mounted on a cold plate in the cargo bay of SL 1 Exposure Facilities, Fig. 3 Exposure tray of the Exobiology Radiation Assembly (ERA), which was mounted on the EURECA platform (Credit: ESA, from Horneck et al 2010) also used to study the mineral decomposition and microbial survival during atmospheric reentry within the ▶ STONE experiments (Brandstätter et al 2008;Cockell et al 2007;de la Torre et al 2010). Advanced exposure facilities with up to four times the capacity of the ES029 experiment of SL 1 were developed by the ▶ European Space Agency (ESA) with the Exobiology Radiation Assembly (ERA) for the ▶ EURECA mission (Fig.…”