A lunar-based solar observatory (planned for expansion) will support the Space Exploration Initiative (SEI) by providing solar flare alerts and high quality scientific data. One candidate instrument for the proposed observatory, a vector magnetograph, will provide scientists with vector magnetic field data at a level of resolution of approximately one-half an arc second, the scale of important physical processes. Scientists will use the vector data from this instrument to develop flare prediction capabilities. The instrument, consisting of a 30 cm Cassegrain telescope system, will be placed on the lunar nearside, making long duration studies of solar activity (of order 14 days) possible. The vector magnetograph will have a temporal resolution on the order of three minutes, an operational lifespan of five years, and will be serviceable by crew of the First Lunar Outpost (FLO). This instrument, based on a currently operating vector magnetograph at NASA's Marshall Space Flight Center, is under study for placement on the Moon using either Johnson Space Center's Common Lunar Lander or crew from the First Lunar Outpost. This paper will review the scientific need to place a vector magnetograph on the Moon, outline the design for such an instrument, describe the preliminary requirements for the launch vehicle and lander, and will recommend a more penetrating study to determine the optimum optical design for the instrument, the best materials, and the environmental effects.