Astroecology, cosmo-ecology, and the future of life

Abstract

Astroecology concerns the relations between life and space resources, and cosmo-ecology extrapolates these relations to cosmological scales. Experimental astroecology can quantify the amounts of life that can be derived from space resources. For this purpose, soluble carbon and electrolyte nutrients were measured in asteroid/meteorite materials. Microorganisms and plant cultures were observed to grow on these materials, whose fertilities are similar to productive agricultural soils. Based on measured nutrient contents, the 10²² kg carbonaceous asteroids can yield 10¹⁸ kg biomass with N and P as limiting nutrients (compared with the estimated 10¹⁵ kg biomass on Earth). These data quantify the amounts of life that can be derived from asteroids in terms of time-integrated biomass [<em>BIOTA</em>_int = biomass (kg) × lifetime (years)], as 10²⁷ kg-years during the next billion years of the Solar System (a thousand times the 10²⁴ kg-years to date). The 10²⁶ kg cometary materials can yield biota 10 000 times still larger. In the galaxy, potential future life can be estimated based on stellar luminosities. For example, the Sun will develop into a white dwarf star whose 10¹⁵ W luminosity can sustain a <em>BIOTA</em>_int of 10³⁴ kg-years over 10²⁰ years. The 10¹² main sequence and white and red dwarf stars can sustain 10⁴⁶ kg-years of <em>BIOTA</em>_int in the galaxy and 10⁵⁷ kg-years in the universe. Life has great potentials in space, but the probability of present extraterrestrial life may be incomputable because of biological and ecological complexities. However, we can establish and expand life in space with present technology, by seeding new young solar systems. Microbial representatives of our life-form can be launched by solar sails to new planetary systems, including extremophiles suited to diverse new environments, autotrophs and heterotrophs to continually form and recycle biomolecules, and simple multicellulars to jump-start higher evolution. These programs can be motivated by life-centered biotic ethics that seek to secure and propagate life. In space, life can develop immense populations and diverse new branches. Some may develop into intelligent species that can expand life further in the galaxy, giving our human endeavors a cosmic purpose.