An artist's concept of an Independent Lunar Surface Sortie (ILSS), one of the potential future options for space activity being studied. The picture appeared in a September 1977 publication from the NASA-JSC Program Planning Office entitled A Compendium of Future Space Activities. This concept is not currently budgeted and there are no plans for construction of such hardware at this time. The ILSS configuration consists of a crew and equipment module; a lunar transport vehicle (LTV) for landing and takeoff, and two experiment/exploration payloads. The LTV is used for descent from lunar orbit, landing and ascent back to lunar orbit. Its single-stage booster uses LOX and LH2 propellants. During an ILSS the LTV is abandoned after the crew and equipment module is joined with the orbit transfer vehicle for return to Earth. The term 'independent' signifies that each mission is self-supporting as were the Apollo lunar missions.