Gedex  Systems Inc
Space Inertial Navigation ( SPIN ) Technology Development — Inertial  navigation is a technology that allows vehicles to determine how their position  has changed over time, without needing to use outside resources (such as GPS).  Currently, spacecraft operators must rely on external references such as radio  tracking for navigation, but a method of autonomous navigation is highly  desired for situations where ground-based communications are not possible. However, all current inertial navigation  instruments suffer from an unavoidable drifting bias, causing a position error  in the navigation solution which grows rapidly with time. The inaccuracy grows  after a few hours to a level that is unacceptable for most space flight  applications, especially for long-term exploration-class missions to other  planets. Recently, Gedex developed a method using a pair of gimballed  accelerometers that completely eliminates the drifting bias, slowing down the  degradation of the navigation solution to the point where it can be useable for  weeks or months. T