Abstract: A spacecraft architecture and accompanying standard allows for the creation of a spacecraft using an assortment of modules that comply with the standard. The standard preferably includes both mechanical and electrical compatibility criteria. To assure physical/mechanical compatibility, the structure of each module is constrained to be compatible with any other compatible module. To minimize the interference among modules, the extent of each module in select dimensions is also constrained. To assure functional compatibility, a common communication format is used to interface with each module, and each public-function module is configured to respond to requests for function capabilities that it can provide to other functions. Each module is preferably designed to provide structural support to the assemblage of modules, and an anchor module is provided or defined for supporting the entire assemblage and coupling the assemblage to other structures, such as a launch vehicle.

Abstract: A receiving system dynamically searches the communications band for transmissions of messages having the same nominal communications parameters, including the use of the same spreading code, but having potentially different specific frequencies and code-phases. The receiver, which is independent of the transmitters, samples the communications band at each code-phase of the spreading code over a span of downconverted transmission frequencies. When a message element is detected at a particular code-phase and frequency, it is forwarded to a demodulator that demodulates the message and sends it to its intended destination. In a preferred embodiment, a progressive Fourier Transform is used to incrementally determine the power level at each successive code-phase at a given frequency, thereby substantially reducing the time required to search for transmissions at each discrete code-phase.

Abstract: A receiving system allows for the coherent detection of a spread-spectrum transmission at any point in time during the transmission, thereby avoiding the need to identify the start of the transmission during the transmission-detection process. An input buffer captures the transmissions on a communication channel using a moving time-window. A detector processes a time-slice from the input buffer and identifies all of the simultaneously transmitting transmitters during that time-slice. As each transmitter is identified, the demodulator traces back-in-time to identify where the message can first be detected in the input buffer. The transmission includes suitable characteristics to facilitate detection and demodulation of the message content, but need not contain a preamble to allow the detection process.

Abstract: A receiving system dynamically searches a communications band for transmissions of messages having the same nominal communications parameters, including the use of the same spreading code, but having potentially different specific frequencies and code-phases. The receiver samples the communications band at each code-phase of the spreading code over a span of down-converted transmission frequencies. When a message element is detected at a particular code-phase and frequency, it is forwarded to a demodulator that demodulates the message and sends it to its intended destination. This technique allows each transmitter to be independent of the receiver. In a preferred embodiment of this invention, a Fast M-Sequence Transform (a Walsh-Hadamard Transform) is used to determine the power level at multiple code-phases at a given frequency in parallel, thereby substantially reducing the time required to search for transmissions at each discrete code-phase.

Abstract: A receiving system dynamically searches a communications band for transmissions of messages having the same nominal communications parameters, including the use of the same spreading code, but having potentially different specific frequencies and code-phases. The receiver samples the communications band at each code-phase of the spreading code over a span of down-converted transmission frequencies. When a message element is detected at a particular code-phase and frequency, it is forwarded to a demodulator that demodulates the message and sends it to its intended destination. This technique allows each transmitter to be independent of the receiver. In a preferred embodiment of this invention, a Fast M-Sequence Transform (a Walsh-Hadamard Transform) is used to determine the power level at multiple code-phases at a given frequency in parallel, thereby substantially reducing the time required to search for transmissions at each discrete code-phase.

Abstract: A receiving system dynamically searches the communications band for transmissions of messages having the same nominal communications parameters, including the use of the same spreading code, but having potentially different specific frequencies and code-phases. The receiver, which is independent of the transmitters, samples the communications band at each code-phase of the spreading code over a span of downconverted transmission frequencies. When a message element is detected at a particular code-phase and frequency, it is forwarded to a demodulator that demodulates the message and sends it to its intended destination. In a preferred embodiment, a progressive Fourier Transform is used to incrementally determine the power level at each successive code-phase at a given frequency, thereby substantially reducing the time required to search for transmissions at each discrete code-phase.

Abstract: A thermal management system for a spacecraft module includes a baseplate and wall system that is precharacterized to provide a given level of thermal performance regardless of an orientation of the spacecraft relative to a source of solar energy. The system is characterized at a worst-case hot orientation, and at a worst-case cold orientation. The characterization provides a maximum temperature and a minimum temperature of components mounted on the baseplate as a function of the height of the walls. The height of the walls is selected to provide a suitable temperature range for the components, based on the power dissipation of the components. The system is designed to be symmetric, so that this temperature range is assured regardless of the orientation of the spacecraft.

Abstract: Communications from autonomous spread-spectrum transmitters are received by dynamically searching the communications band for messages having the same communications parameters, including the use of the same spreading code, but having potentially different code-phases. A receiver that is independent of the transmitters samples the communications band at each code-phase of the spreading code. When a message element is detected at a particular code-phase, the message element is appended to a queue associated with this code-phase. Message elements detected at other code-phases are appended to queues associated with the corresponding code-phases. Gaps between message elements at each code-phase define the beginning and end of each message. In a preferred embodiment of this invention, the processing of the samples occurs at a frequency above the baseband of the encoded message. An FFT processor provides a magnitude and phase associated with each detected message.

Abstract: A redundant information processing system with sufficient reliability is provided at a moderate cost without any part that could be a single fault point in the system. In the redundant information processing system in which an actuator 5 is controlled based on a signal from a sensor 4, each of processing devices 1A to 1C collects command signals from other processing devices and determines which command signal to be valid according to a logical decision, for example, a majority decision. When the command signals of more than two of the processing devices including the relevant processing device which determines are valid, the command signals are output according to priority while a control information blocking signal is output to a processing device other than those which are valid.

Abstract: A communication system is provided that allows the use of low-cost, low-power remote terminal units that communicate substantially asynchronously and independently to a base station. To minimize cost and complexity, the remote terminal units are configured similarly, including the use of substantially identical transmission schemes, such as a common Direct Sequence Spread Spectrum (DSSS) code. To minimize collisions among transmissions, the communication system is designed to use a high-gain antenna with a limited field of view, to limit the number of cotemporaneous, or overlapping transmissions that are received at the base station. To cover a wide area, the limited field of view is swept across the area of coverage. To overcome potential losses caused by collisions, the remote terminal units are configured to repeat transmissions; to minimize repeated collisions, the repeat interval and/or duration is randomized.

Abstract: The excess space and weight capacity that is typical of a launch of large satellites to high-energy orbits, such as a geosynchronous orbit, is used to deploy small satellites at a substantially lower-energy orbit, such as a low-earth orbit. An orbit-transfer vehicle provides the navigation, propulsion, and control systems required to transport a payload satellite from a geosynchronous-transfer orbit (GTO) to a predetermined low-earth orbit (LEO). Depending upon the particular configuration, upon achieving the low-earth orbit, the orbit transfer vehicle either releases the payload satellite, or remains attached to the payload satellite to provide support services, such as power, communications, and navigation, to the payload satellite. To reduce the fuel requirements for this deployment via the orbit-transfer vehicle, the orbit-transfer vehicle employs aerobraking to bring the satellite into a low-earth orbit.

Abstract: The in situ remote sensing system of this invention includes a plurality of sensors that are distributed about an area of interest, and a satellite communications system that receives communications signals from these sensors. The satellite communications system determines the location of each sensor at the time that the sensor transmits its communications signal, thereby facilitating the mapping of the value of the sensed parameter about the area of interest. In a preferred embodiment, the satellite communications system transmits a trigger signal to the sensors that are within the satellite antenna's field of view, and the sensors transmit only in response to the trigger signal. The sensors may be conventional active transmitters or passive transponders that receive their operating energy from a received trigger signal. The sensing devices within the sensor may also provide the operating energy for the sensor using, for example, photocells, piezoelectrics, and thermocouples.

Abstract: The excess space and weight capacity of a conventional launch vehicle for a high-energy orbit, such as GEO, is used to deploy satellites to a low-energy orbit, such as LEO. In a preferred embodiment, an orbit-transfer vehicle provides the navigation, propulsion, and control systems required to transport a payload satellite from a high-energy-transfer orbit, such as GTO, to a predetermined low-energy orbit. Upon entering the low-energy orbit, the payload satellite is released from the orbit-transfer vehicle. To reduce the fuel requirements for this deployment via the orbit-transfer vehicle, a preferred embodiment includes aerobraking to bring the satellite into a low-earth orbit.

Abstract: An inspection satellite is deployed in proximity to another satellite. The inspection satellite contains monitoring equipment and provides diagnostic information to a earth station to facilitate diagnosis of the other satellite and its equipment. The inspection satellite includes a flight control system that maintains the probe satellite in proximity to the satellite being monitored. In a preferred embodiment, the flight control system can also maintain the inspection satellite in an orbit about the satellite being monitored, to facilitate diagnostics based on patterns of signals. The monitoring equipment in a preferred embodiment for a transponder satellite includes an ability to monitor incoming signals and to compare the emissions from the satellite to them, to determine performance characteristics of the satellite equipment being monitored, such as phase shift and gain.

Abstract: The satellite communications system of this invention provides high-gain coverage to a wide geographic area with a minimum number of satellites. The satellites each include a high-gain antenna that periodically sweeps the satellite's service area to receive the messages from remote terminal units within the entire service area. In order to provide high gain, the antenna is designed to have a narrow beamwidth in at least one dimension. To cover the entire area, the antenna's field of view is swept across the entire service area. In the preferred embodiment, the antenna's field of view is essentially rectilinear, having a narrow beamwidth in one dimension and a beamwidth that extends across the entire service area in the other dimension, such that the sweeping effect is akin to that of a common push-broom. Because of the high gain of the satellite antenna, communications via the satellite can be accomplished using a low-gain wide-beamwidth antenna at the remote terminal unit.