Mars Spirit Lander and Bonneville Crater in Color
Image Credit: NASA/JPL-Caltech/Univ. of Arizona
Panspermia is a concept which portrays how life might be distributed throughout the universe. These means include a wide variety of astronomical or celestrial objects including meteors, comets, asteroids, and factors such as the solar wind. The theory of panspermia, however does not really address how life began in the first place.
As man has ventured out into space, with human space travel, or has used unmanned spaceflight, the issue of man (or machine) as a vector or agent of panspermia has become an issue. This issue parallels the concept of jet travel and airports as a vector in spreading contagion. Migratory birds have been vectors for centuries, landing in Qinghai Lake, China, a saline and alkaline lake and migratory crossroads or in the Izembek National Wildlife Refuge in Alaska, along the Bering Sea. . Such bird migratory pathways provide fertile ground for recombination and spread of various contagions.
The NASA photo of the Bonneville Crater and Mars Spirit Lander depicts an impact crater on Mars. Such an impact would have created a large amount of energy upon impact. Many theories of life involve the discussion of how reorganization and complexity arises as energy is input into a system. The Miller and Urey experiment in 1953 attempted to address this issue through recreation of a primordial atmosphere laced with water, methane and lightning storms.
Henry Eyring, a chemist, discovered Actual Rate Theory or Transition State Theory, which discusses reaction rates of chemicals in the context of potential energy states, complexes activated by chemical reactions, entropy considerations and products formed by the chemical reaction. In considering the input of exogenous energy into a system, this theory would be important in examining the potential reactions that might take place, as the reaction may change the system through transformational change.
In considering the issue of panspermia, therefore, there are a couple of issues; the development of a system and then the spread of that system. Issues of energy and mixing concern the development or the boot-strapping of a system through transformational change, while panspermia addresses the spread. Where panspermia occurs through media that spread via impact, the two issues (bootstrapping and spread) tend to co-exist to some extent.
The concept of panspermia requires a vector that is resilient. It must be able to adapt to environmental factors such as extremes of temperature, must be able to resist impact as well as radiation and other factors such as high levels of salinity. Such organisms, extremophiles fit a profile as a candidate for panspermia.
Santa Catalina Mountains seen from Saguaro National Park, Arizona
An endospore is a tough non-reproductive surface that lies dormant for an extended period of time, and can be later revived after many years to a vegetative state.
Anthrax is a bacillus, and may exist in the dormant state as an endospore. According to a World Health Organization document on studies of anthrax endospores (bacillus anthracis), "Sporulation requires the presence of free oxygen. In the natural situation, this means the vegetative cycles occur within the low oxygen environment of the infected host and, within the host, the organism is exclusively in the vegetative form. Once outside the host, sporulation commences upon exposure to the air and the spore forms are essentially the exclusive phase in the environment." Spores are thus spread by release of spores by the dying host into the environment where they are taken up by another animal.
The focus of the AEM article is on the very issue of panspermia, the issue of transference of microbes through spaceflight, It concerns the measurement of characteristics of various endolithic spore populations obtained through a variety of near surface granites and basalts and even the ultra clean environments of spacecraft assembly facilities.
Blue fluorescence obtained through medium wavelength UV illumination, distinguished certain endospores obtained from near surface granites. Endospores were grouped into species or strains based on their rRNA gene sequences. Numbers and diversity of endospores from granite were greater than those obtained from basalts. This may be due to the lower porosity of basalt versus granite. Limited subsets of Bacillus spp. appeared to occur in certain rock environments that favored them and not other strains. Certain bacillus strains (bacillus subtilis) were used as proxies for bacillus anthracis fluorescence properties in the study.
The issue of panspermia is a very important one, set in the context of space exploration and in consideration of how extraterrestrial impacts may have impacted (and may still be impacting) human life. The AEM study provides interesting results as to the diversity and characteristics of Bacillus spp. from a variety of environments, including, importantly, granite, set in the context of fluorescence properties. A bacillus such as anthrax, as studied by the World Health Organization (WHO) or the CDC may provide clues as to how bacillus and endospores fit into our evolutionary framework.
