Could an Astronaunt's Corpse Spread Life to Other Planets?

One day, it’s bound to happen. An astronaut dies in space.

Maybe the death occurred en route to Mars. Maybe she was interstellar, on board solo spacecraft. Or maybe the body was thrust out an airlock, a burial at space.

That corpse (or the corpse’s spacecraft) could spend anywhere from decades to millions of years adrift. It would coast listlessly in the void, until the creeping tendrils of gravity eventually pulled it into a final touchdown. Likely this corpse will burn up in a star.

But lets say it lands on a planet. Could our corpse, like a seed on the wind, bring life to a new world?

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Extraordinary Claim: Venus COuld be the Source of Complex Life on Earth

The Venus Hypothesis

Author:

Cartwright

Abstract:

Current models indicate that Venus may have been habitable. Complex life may have evolved on the highly irradiated Venus, and transferred to Earth on asteroids. This model fits the pattern of pulses of highly developed life appearing, diversifying and going extinct with astonishing rapidity through the Cambrian and Ordovician periods, and also explains the extraordinary genetic variety which appeared over this period.

Endospores of Bacillus subtilis can Only Survive Impacts up to 300 m/s

Survivability of bare, individual Bacillus subtilis spores to high-velocity surface impact: implications for microbial transfer through space

Authors:

Barney et al

Abstract:

Laboratory experiments show that endospores of Bacillus subtilis survive impact against a solid surface at velocities as high as 299+/− 28 m/s. During impact, spores experience and survive accelerations of at least 10^10 m/s2. The spores were introduced into a vacuum chamber using an electrospray source and accelerated to a narrow velocity distribution by entrainment in a differentially-pumped gas flow. Different velocity ranges were studied by modifying the gas flow parameters. The spores were electrically charged, allowing direct measurement of the velocity of each spore as it passed through an image charge detector prior to surface impact. Spores impacted a glass surface and were collected for subsequent analysis by culturing. Most spores survived impact at all measured velocities. These experiments differ fundamentally from other studies that show either shock or impact survivability of bacteria embedded within or on the surface of a projectile. Bacteria in the present experiments undergo a single interaction with a solid surface at the full impact velocity, in the absence of any other effects such as cushioning due to microbe agglomerations, deceleration due to air or vapor, or transfer of impact shock through solid or liquid media. During these full-velocity impact events the spores experience extremely high decelerations. This study is the first reported instance of accelerations of this magnitude experienced during a bacteria impact event. These results are discussed in the context of potential transfer of viable microbes in space and other scenarios involving surface impacts at high velocities.

Evidence of Organic Molecules From Another Star System From Carbonaceous Chondrite Asteroid

Multiple Cosmic Sources for Meteorite Macromolecules?

Authors:

Sephton et al

Abstract:

The major organic component in carbonaceous meteorites is an organic macromolecular material. The Murchison macromolecular material comprises aromatic units connected by aliphatic and heteroatom-containing linkages or occluded within the wider structure. The macromolecular material source environment remains elusive. Traditionally, attempts to determine source have strived to identify a single environment. Here, we apply a highly efficient hydrogenolysis method to liberate units from the macromolecular material and use mass spectrometric techniques to determine their chemical structures and individual stable carbon isotope ratios. We confirm that the macromolecular material comprises a labile fraction with small aromatic units enriched in 13C and a refractory fraction made up of large aromatic units depleted in 13C. Our findings suggest that the macromolecular material may be derived from at least two separate environments. Compound-specific carbon isotope trends for aromatic compounds with carbon number may reflect mixing of the two sources. The story of the quantitatively dominant macromolecular material in meteorites appears to be made up of more than one chapter.

Lithopanspermia: Did the Chicxulub Impact Seed Europa and the Rest of the Solar System With Life?

Seeding Life on the Moons of the Outer Planets via Lithopanspermia

Authors:

R. J. Worth, Steinn Sigurdsson and Christopher H. House

Abstract:

Material from the surface of a planet can be ejected into space by a large impact, and could carry primitive life forms with it. We performed n-body simulations of such ejecta to determine where in the Solar System rock from Earth and Mars may end up. We find that, in addition to frequent transfer of material among the terrestrial planets, transfer of material from Earth and Mars to the moons of Jupiter and Saturn is also possible, but rare. We expect that such transfer is most likely during the Late Heavy Bombardment or during the next one or two billion years. At this time, the icy moons were warmer and likely had little or no icy shell to prevent meteorites from reaching their liquid interiors. We also note significant rates of re-impact in the first million years after ejection. This could re-seed life on a planet after partial or complete sterilization by a large impact, which would aid the survival of early life during the Late Heavy Bombardment.

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