Any alien self-replicating interstellar probe should have left remnants of its self-replication activities in our asteroid belt. The asteroid belt - a feature that may be common to planet-bearing stellar systems near the snow line - is an obvious target for its proximity to solar energy, its ready source of a wide range of materials and that indigenous life is unlikely to be resident. We have developed a lunar industrial ecology that indicates how an efficient industrial base may be implemented that is readily adaptable to asteroids. Again, adapting it to interstellar probe applications appears to be feasible. Indeed, we would argue that self-replication technology must precede laser-propelled interstellar spacecraft. Self-replication technology renders this approach to interstellar propulsion preferable to nuclear pulse propulsion which requires exotic structural materials and propellant mined from gas giants. Vast edifices require considerable resources to construct. The industrial ecology we have developed as part of a self-replication process could accommodate such productivity growth. Even so, the industrial ecology has a well-defined set of processes that yield reagents and products in fixed relationships to each other. With minimal assumptions, we suggest that fused silica glass will be the dominant product - for Fresnel lenses as solar concentrators for generating power for the laser transmitters and for the laser focusing optics. Extraction of such large amounts of silica should yield technosignatures that depart from solar abundances. There are several ways to yield silica from common rock-forming silicates but all leave characteristic residues including clays and talc. For example, the common pyroxene enstatite in stony asteroids may be rapidly artificially weathered with HCl: Mg2Si2O6 + HCl + H2O → Mg3Si4O10(OH)2 + H4SiO4 + MgCl2.nH2O. This yields soluble silica (silicic acid from which silica may be precipitated), magnesium chloride and talc. Given that Cl is scarce on asteroids, it would be recycled to re-constitute HCl reagent. We have adopted an artificial chemical weathering method for generating silica that resembles natural aqueous processes so it would be challenging to discriminate qualitatively. Although talc may be employed as a dry lubricant, a large excess of talc with a paucity of enstatite might suggest an artificial origin. Hence, in the asteroid belt, discrimination would be quantitatively through scale.
44th COSPAR Scientific Assembly. Held 16-24 July
- Pub Date:
- July 2022