A number of astrophysical observatory concepts were studied under the overall direction of the NASA Astrophysics Division in support of NASA’s 90‐day study of the Human Exploration Initiative. The four observatory concepts described here were investigated at JPL. In three of them, interferometric techniques would be used to acquire high resolution synthetic aperture
images in several different parts of the electromagnetic spectrum: in the UV/Visible Near Infrared; the Submillimeter; and the Very Low Frequency (1 to 30 MHz region). The fourth is a Gravitational Wave Detector which uses laser optical interferometry to measure the strains induced by the passage of a gravitational wave. The observatory concepts reflect the constraints on lunar surface science deployment anticipated for the Human Exploration Initiative in the period 2002 through 2015.