MODERN SOLUTIONS FOR ATMOSPHERIC REENTRY FLIGHT NAVIGATION -THE CAPREE DEVELOPMENTS

摘要

In the frame of the ESA TRP "CapRee" study, innovative navigation solutions have been designed and prototyped to support the needs for a fully autonomous and high accuracy sample return capsule. The navigation solution currently being designed will be further prototyped in the project phase 2 - starting early 2000 - and tested on a realtime test bench to provide for a self-standing, versatile and high accuracy solution for advanced atmospheric vehicles navigation. A key aspect of all re-entry vehicles is the presence of a black-out phase, where all RF transmissions to and from the vehicle are suppressed. During such a phase the vehicle has to navigate in "blind mode": this implies the need for an inertial navigation system (INS) as the core of the navigation function. The INS solution will however diverge and must be updated through external means, especially for the class of landing accuracy envisaged in the CapRee study: the 50 meter accuracy strongly drives the use of a DGPS system in the vicinity of the landing site. The presence of a GPS receiver on-board the vehicle may also serve to update the INS during the flight: in-flight alignment is a key factor for a cost effective solution, the main challenge being to avoid the use of an external optical sensor.