Planetary and Space Science 104 (2014) 234–243 Contents lists available at ScienceDirect Planetary and Space Science journal homepage: www.elsevier.com/locate/pss In situ biological resources: Soluble nutrients and electrolytes in carbonaceous asteroids/meteorites. Implications for astroecology and human space populations Michael N. Mautner a,b,n a Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284-2006, USA b Soil and Physical Sciences Department, Lincoln University, Lincoln, New Zealand article info abstract Article history: Ecosystems in space will need in-situ bioavailable nutrients. The measured nutrients in meteorites allow Received 16 February 2014 experiment-based estimates of nutrients in asteroids, and of the biomass and populations that can be Received in revised form derived from these in situ bioresources. In this respect, we found that carbonaceous chondrite 24 September 2014 meteorites can support microorganisms and plant cultures, suggesting that similar asteroid materials Accepted 1 October 2014 are also biologically fertile. The sustainable biomass and populations are determined by the available Available online 16 October 2014 resource materials, their yields of nutrients and biomass, the biomass needed to support human Keywords: populations, the duration of the ecosystem, and wastage. The bioavailable C, N, and electrolytes in Astroecology carbonaceous chondrite meteorites vary as CM24CR24CV34CO34CK44CK5 in correlation with Asteroids petrologic type, including aqueous alteration. Their average bioavailable C, N, K and P can yield 2.4, 3.5, Biomass 2.5, and 0.08 g biomass/kg resource material, respectively, showing phosphorus as the limiting nutrient. Meteorites 19 Solar system On this basis, soluble nutrients in a 100 km radius, 10 kg resource asteroid can sustain an ecosystem of 8 9 Space settlements 10 kg biomass and a human population of 10,000 for 410 years, and its total nutrient contents can sustain a population of one million, by replacing a wastage of 1% of the biomass per year. Overall, the total nutrient contents of the 1022 kg carbonaceous asteroids can yield a biomass of 1020 kg that supports a steady-state human population of one billion during the habitable future of the Solar System, contributing a time-integrated biomass of 1022 kg-years. These astroecology estimates use experimental data on nutrients in asteroids/meteorites to quantify the sustainable biomass and human populations in this and similar solar systems. & 2014 Elsevier Ltd. All rights reserved. 1. Introduction Carbonaceous C-type asteroids can be physically accessible in-situ biological sources of organics and electrolytes, provide soils Human expansion in the Solar System has been contemplated for for agriculture and extracts for hydroponics, produce food for over a century since Tsiolkovsky, and it is a long-term goal of NASA settlements on the asteroids or on terraformed planets and space (Rynin, 1971; O’Neill, 1974, 1977; McKay et al., 1991; Sagan, 1994; colonies (Sears, 1973; O’Neill, 1974, 1977; Bunch and Chang, 1980; O’Keefe, 2002; Griffin, 2014). Astroecology experiments with carbo- Ming and Henninger, 1989; Lewis, 1993; Brearley and Jones, 1998; naceous meteorites showed that microorganisms, plant cultures and Dyson, 2000). shrimp hatchlings can grow on these materials (Mautner, 2002a, b) Although large populations can be accommodated by space res- Therefore biological materials for space-based ecosystems and human ources, there have been few experiment-based tests whether these populations can be derived from these in-situ asteroid resources resources can support biological growth, or data for estimating pote- (Mautner, 2002a, b; Montague et al., 2012), similarly to in situ resource ntial yields of biomass. Concerning asteroid resources, it is necessary to utilization (ISRU) for industrial and structural materials (O’Leary, 1977; establish the soil fertilities of model carbonaceous meteorites. For Matloff et al., 2001; Bolonkin, 2013). these purposes, agricultural soil fertility tests (McLaren and Cameron, 1996) were miniaturized for the available sub-gram meteorite samples (Mautner et al., 1995, 1997; Mautner 1997, 1999). These bioassays n Corresponding author at: Department of Chemistry, Virginia Commonwealth showed that the Murchison CM2 and Allende CV3 carbonaceous University, Richmond, VA 23284-2006, USA. Tel.: þ1 804 827 1222; fax: þ1 804 828 8599. chondrites contain bioavailable, soluble organic carbon and electro- E-mail address: [email protected] lytes including nitrate and phosphate. The small hydroponic cultures http://dx.doi.org/10.1016/j.pss.2014.10.001 0032-0633/& 2014 Elsevier Ltd. All rights reserved. M.N. Mautner / Planetary and Space Science 104 (2014) 234–243 235 supported bacteria, algae, asparagus and potato cultures, and brine Table 1 shrimp. This soil fertility ranking showed that the fertilities of carbo- Total and water-soluble carbon and nitrogen in carbonaceous chondrites. naceous chondrite materials are similar to productive terrestrial soils. Ca Cb After Cc Extract. Na Nb N c Martian meteorites were also fertile due to their high extractable Total extract. % of total Total After extract % phosphate. These bioassays confirmed that C-type asteroid materials (g/kg) extrac. of total can contribute significantly to early and future life in the Solar System (Mautner 2002a, b, 2005; Mautner and Sinaj, 2002; Kennedy et al., Murchison CM2 21.7 17.0 22 0.99 0.84 15 ALH 83102 CM2 17.1 16.8 2 0.67 0.64 5 2007). GRA 95229 CR2 11.7 9.8 16 0.94 0.68 28 To evaluate space development quantitatively, it is necessary to Allende CV3 4.8 3.8 20 0.42 0.29 30 assess the biomass, ecosystems and populations that can be derived ALH 84028 CV3 2.0 2.5 0.067 0.033 51 from asteroid resources. Such quantitative estimates can be obtained ALH 83108 CO3 0.78 0.75 99 0.055 0.019 65 fromthebioavailablenutrientcontents in carbonaceous meteorites, ALH 85002 CK4 0.71 0.52 26 0.063 0.014 77 EET 92002 CK5 0.28 0.29 0 0.11 0.010 91 that represent their parent C-type asteroids. In addition to CM2 and CV3 materials tested before, resources a Concentrations of C or N in meteorite (g/kg). Estimated uncertainties from the may be obtained also from other types of asteroids. In this respect, average stds of four replicates as percentage of the values reported in the table: For tests showed that stony-iron asteroids/meteorites also support C, 13.4%; for N, 12.1% of the reported values. b Remaining C or N content (g/kg) after extraction at solid/solution ratios of autotrophic plant cultures (Marcano et al., 2005). In order to adapt 1:20 at 20 C for 4 days. to these in-situ resources, genetically engineered organisms may c Percent of original C or N content removed by water extraction. be designed to develop microbial communities (Mautner et al., 1997; Olsson-Francis et al., 2009; Montague et al., 2012). The present paper surveys nutrient contents in various carbonac- conductivity detection. Samples analyzed in this manner are filtered eous chondrite meteorites. Combining these data and the elemental through a 0.2 μmmembranefilter prior to analysis. The average compositions of dry biomass (Bowen, 1966), allows calculating the standard deviations of all the four replicate experiments for extracted biomass and populations that can be derived from asteroids. In turn, anions and cations was 20% which can be considered as the unce- this information can be combined with estimates of the total mass of rtainty of the values. However, the standard curve calibrations of the asteroids, and of the expected habitable timespan of the Solar System measured concentration have minimum values below which larger (Lewis, 1973; Lewis, 1997), to assess the biomass and human popu- uncertainties may apply. Under our extraction conditions of 25 mg lations that can be sustained by asteroids here and eventually in solids in 0.5 ml water, these lower limits of accurate measurements other solar systems, such as the water-containing asteroid observed translate to measured extractable contents in the solids of o0.04 g/ þ À recently about the white dwarf star DG 61 (Farihi et al., 2013). kg for all cations, except 0.02 g/kg for NH4 ando0.04 g/kg for Cl Beyond biological resources, biomass and populations in space and BrÀ,ando0.01 g/kg for Nitrate-N, Phosphate-P and Sulfate-S. þ þ depend on many factors, such as meteorite mineralogy and org- The similar chemistry of NH4 and K (Meot-Ner et al., 1996), may anic contents, that may affect extraction; also in situ resources for allow interference between these ions in chromatography, but the habitats; human and materials transport; and energy sources. chromatographic peaks of all the other cations were well resolved. These subjects require research beyond the scope of this paper, Samples of Murchison and Allende were gifted by the American but the quantitative estimates of the large scope of life in space Museum of Natural History and from the Victoria Museum of may encourage more such research. Australia, or obtained from commercial sources. These samples were collected originally from observed falls and are not significantly weathered. The Antarctic meteorite samples were donated by NASA, 2. Materials and methods with the classification and weathering status (A¼minor rustiness; B¼moderate rustiness; C¼severe rustiness; e¼evaporate minerals Water-soluble materials were extracted from hand-ground met- visible to the naked eye): ALH 83102, CM2, B/Ce; GRA 95229, CR2, A; eorite powders. The particle sizes in the powders were mostly in the ALH 84028, CV3, Ae; ALH 83108, CO3, A; ALH 85002, CK4, A; EET 1–5 μm range with a smaller fraction up to 40 μm, with particle sizes 92002, CK5, A/Be. In the present and previous work, Allende and comparable to terrestrial soils. Murchison samples were obtained from various sources, and may Samples of 25 mg of the meteorite powders were placed in have originated from different meteorite fragments, but the resulting 0.5 ml deionized water at solid/solution ratios (w/w) of 1:20 and extracts were generally consistent.