Inflatable habitats are pressurised modules for use in an outer space environment to support human life. They have frequently been proposed for use in space applications to provide a greater volume of living space for a given mass. The first serious design and manufacture of an inflatable space habitat was in 1961 with a space station design produced by Goodyear (although this design was never flown).A proposal released in 1989 by Johnson Space Center's Man Systems Division outlined a 16 metres (52 ft) diameter spherical habitat lunar outpost which was partially buried in the lunar surface.