 In December 1988 the ad hoc Citizens' Advisory Council on National Space Policy was briefed on the concept by Hunter and others.The general concept was endorsed by the Council and by High Frontier, Inc., a Washington-based group headed by Lt. Gen. Daniel O. Graham that lobbied for SDI programs.Working together, Hunter and High Frontier convinced SDI management and other national officials that a study should be initiated to determine once and for all the feasibility of SSTO vehicles for military missions.