A modular spacecraft and fabrication method for producing a spacecraft of the kind that forms an enclosure and framework for installation of the external and internal subsystems of the spacecraft. The primary structure of the spacecraft is formed as a split shell enclosure including composite formed upper and lower shell portions. The spacecraft, with the shells open, provides an extremely high degree of access during the assembly, installation and test of the spacecraft. A self-aligning tapered joint is formed at respective contacting lip surfaces of at least one set of common end walls of the upper and lower shell portions. Heat pipes are formed integral within the composite structure of selected walls of the shell portion to provide thermal regulation to the spacecraft and the subsystems contained therein. Removable battery modules are incorporated into the end wall structure of the upper shell portion. Also disclosed is an arrangement for distributing the subsystem electronics over the shell of the spacecraft in a manner that maximizes power, thermal and weight efficiencies. The distributed electronics arrangement includes a number of standardized plug-in interface cards which contain the various subsystem electronics and a common backplane for receiving the interface cards. The common backplane is mounted directly to the composite shell structure and is preferably located over one or more heat pipes for thermal dissipation.
Reaction wheels are placed around an enclosure so that the reaction wheel rotors provide a radiation shield for electronic components inside the enclosure.
A real-time IMU emulation method for GNC method includes the step of receiving real-time flight data from a 6DOF flight simulator and generating simulated IMU electronic signals according to the IMU measurement modules and error modules defined by the user, and injecting said simulated IMU electronic signals into an on-board GNC system which causes the on-board GNC system into "thinking" that the vehicle is really moving. The on-board GNC system which is installed on the vehicle is motionless during the emulation test, so that the testing can be carried out in a laboratory or in an anechoic chamber facility and the IMU emulation can achieve the easy, effective, and least intrusive injection of emulated IMU signals into the INS computer. The present invention has features supporting the final integration of a developmental Guidance, Navigation, or Control (GNC) system installed into a vehicle. It assures testers that GNC avionics on-board vehicle work properly before and during a flight test. It also helps to debug on-board GNC avionics and verify system performance.
A spacecraft control electronics system provides multi-functionality to a spacecraft in a single electronics box. The system is subdivided into a plurality of modular electronic subunits. Each of the modular subunits plugs into a backplane in the electronics box and is positioned side-by-side. A serial data bus in the backplane of the box interconnects the modular subunits to each other. The data bus provides fully redundant, standard interfacing for the modular subunits. The plurality of electronic subunits provides spacecraft attitude determination, control, telemetry and command and data processing functions to the spacecraft as one unit. The electronics box connects to the spacecraft harness via external connectors. The spacecraft has a minimum number of harness connections as a result of the integrated functions in the spacecraft control electronics system. The control system applies selective internal redundancy in its subunits. The CPU subunit has triple mode redundancy through three microprocessors that are voted together to detect and correct errors due to single event upsets. The T&C/GPS subunit has an embedded GPS receiver that performs attitude determination as well as orbital positioning. The modular subunits have a built in self-test that verifies minute circuitry interconnections and detects faults automatically. The subunits are tested as stand-alone subunits, as a part of the spacecraft control electronics system, and/or as part of the spacecraft level integration using this automated built-in self test capability. Faults in the subunits or the system are detected in seconds. The built in self-test feature also provides an end-to-end spacecraft harness verification automatically in minutes. Defective modular subunits are removed and replaced with substitute modular subunits during spacecraft level integration.
