The Single-sided Guarded Hot Plate Method for Comparative Testing of Thermal Radiation Barriers in Vacuum was used to evaluate the performance of a variety of aerogel insulation specimens manufactured by Aspen Aerogels® against one another and against multi-layer insulation (MLI). Testing at the Air Force Research Laboratory (AFRL) shows that the effective thermal resistance, R_e, of all tested aerogel specimens are virtually bounded by the performance of 5-layer and 10-layer MLI specimens over a mean specimen temperature, T_m, range of about 270K to 315K.