the "Q system" of guidance. The "Q" system's revolution was to bind the challenges of missile guidance (and associated equations of motion) in the matrix Q. The Q matrix represents the partial derivatives of the velocity with respect to the position vector. A key feature of this approach allowed for the components of the vector cross product (v, xdv,/dt) to be used as the basic autopilot rate signals-a technique that became known as "cross-product steering." The Q-system was presented at the first Technical Symposium on Ballistic Missiles held at the Ramo-Wooldridge Corporation in Los Angeles on June 21 and 22, 1956. The "Q System" was classified information through the 1960s. Derivations of this guidance are used for today's military missiles. The CSDL team remains a leader in the military guidance and is involved in projects for most divisions of the US military. On August 10 of 1961 NASA Awarded MIT a contract for preliminary design study of a guidance and navigation system for Apollo program. (see Apollo on-board guidance, navigation, and control system, Dave Hoag, International Space Hall of Fame Dedication Conference in Alamogordo, N.M., October 1976 ). Today's space shuttle guidance is named PEG4 (Powered Explicit Guidance). It takes into account both the Q system and the predictor-corrector attributes of the original "Delta" System (PEG Guidance). Although many updates to the shuttles navigation system have taken place over the last 30 years (ex. GPS in the OI-22 build), the guidance core of today's Shuttle GN&C system has evolved little. Within a manned system, there is a human interface needed for the guidance system. As Astronauts are the customer for the system, many new teams are formed that touch GN&C as it is a primary interface to "fly" the vehicle. For the Apollo and STS (Shuttle system) CSDL "designed" the guidance, McDonnell Douglas wrote the requirements and IBM programmed the requirements. Much system complexity within manned systems is driven by "redundancy management" and the support of multiple "abort" scenarios that provide for crew safety. Manned US Lunar and Interplanetary guidance systems leverage many of the same guidance innovations (described above) developed in the 1950s. So while the core mathematical construct of guidance has remained fairly constant, the facilities surrounding GN&C continue to evolve to support new vehicles, new missions and new hardware. The center of excellence for the manned guidance remains at MIT (CSDL) as well as the former McDonnell