© 2004 Robert A. Freitas Jr. and Ralph C. Merkle. All Rights Reserved.

Robert A. Freitas Jr., Ralph C. Merkle, Kinematic Self-Replicating Machines, Landes Bioscience, Georgetown, TX, 2004.

3.14 Freitas Atomic Separator Replicator (1981)

Following in the tradition of Shoulders (Section 4.7) and Taylor (Section 3.10), in 1981 Freitas [1108] privately circulated an unpublished basic technical analysis of the potential problems and performance characteristics of a space-based solar-powered “atomic separator” replicator using a fully-dissociated materials input beam, laser separation of isotopes, and raster-scan production of parts. This analysis was intended as a simple scaling study, not as a full systems design.

In this scenario, raw lunar or asteroidal material is delivered to a parabolic solar furnace where it is heated to ~5000 K at the focus, irradiated by a pulsed-mode laser and electron gun raising the vapor temperature to ~6 eV, collimated and accelerated through metal plates, then passed through bending magnets which remove ionized species for recycling, leaving a collimated hot neutral atomic beam. This beam enters a linear laser isotope separation [1109] chamber in which a series of magnets and tunable excitation lasers allow atoms of selected pure elements to be picked out of the beam and diverted to collectors, with a beam dump at the far end that collects unused material for reuse or disposal. Collected atoms, thus sorted, can then be employed in a beam-deposition scheme in which pure elemental feedstock is ionized and electrostatically delivered to a workpiece, building up parts and larger systems by a raster-scan type deposition process similar to processes which in later years have become known as stereolithography [1110-1119], fused deposition modeling (FDM) [933-935], electrodeposition microfabrication (EFAB^TM) [1122-1124], gas phase solid freeform fabrication (SFF) [1125-1127], and so forth, as briefly reviewed in Section 3.20.

The main device (Figure 3.50) is a cylinder averaging ~5 meters wide and ~20 meters long, not counting 1100 m² of waste heat radiators and 76,400 m² of solar power panels producing 11 MW of power. The estimated net mass throughput of atomically sorted atoms is ~0.00125 kg/sec. Assuming mean system density is ~100 kg/m³ (it is mostly vacuum) and the panels and radiators are 1 cm thick in the complete system deployed in lunar orbit (Figure 3.51), then the atomic separator replicator has a mass of ~120 tons and a net production rate of ~40 tons/year, hence can process its own mass of materials in ~10⁸ sec, a ~3 year replication time.

Last updated on 1 August 2005