Nanorobot manufacturing unit. Computer artwork of a nanorobot assembler using a claw to attach itself to a bacterium. The bacterium is designed to provide the raw materials needed for assembling nanorobots. The attached assembler is designed to build nanorobots. One goal of nanotechnology is to design such self-replicating systems, which would allow large manufacturing projects to become economically viable. Examples of future projects that could use replicating nanorobots include the terraforming of Mars and building space colonies. A danger is that nanoreplicators could convert the Earth's environment from biomass to nanomass, the 'grey goo' problem or global ecophagy.