Abstract: A tether having the special technical feature of multiple primary load-bearing lines and normally slack secondary lines. These primary and secondary lines are connected together with knotless, slipless interconnections so the tether maintains high strength and some of the lines can be cut without failure of the tether when it is operated near the ultimate failure load of the material from which it is constructed. This tether can safely carry load hundreds of times longer than prior art tethers in harsh environments where a single-line tether experiences a substantial risk of failure. The specific industrial applications of an electrodynamic tether system to deorbit satellites and a low Earth orbit to lunar surface tether transport system are all part of the general innovative concept of the invention.

Abstract: The present invention comprises apparatus and methods for using and controlling electrodynamic tethers. The apparatus taught by the present invention uses an interconnected multiwire (compared to the long, narrow single wires of the prior art) conductive tether whose area maximizes electrodynamic drag while simultaneously minimizing the Area-Time-Product swept by the tether during its operating life. The preferred tether length is two kilometers to five kilometers. The preferred tether mass is one percent to five percent of the spacecraft mass. The methods of control taught by the present invention comprise orienting the tether structure at a preferred angle to the local vertical to maximize electrodynamic drag and minimize tether instabilities. The angle of 35.26 degrees to the local vertical line is preferred.

Abstract: A tether having the special technical feature of multiple primary load-bearing lines and normally slack secondary lines. These primary and secondary lines are connected together with knotless, slipless interconnections so the tether maintains high strength and some of the lines can be cut without failure of the tether when it is operated near the ultimate failure load of the material from which it is constructed. This tether can safely carry load hundreds of times longer than prior art tethers in harsh environments where a single-line tether experiences a substantial risk of failure. The specific industrial applications of an electrodynamic tether system to deorbit satellites and a low Earth orbit to lunar surface tether transport system are all part of the general innovative concept of the invention.

Abstract: A tether having the special technical feature of multiple primary load-bearing lines and normally slack secondary lines. These primary and secondary lines are connected together with knotless, slipless interconnections so the tether maintains high strength and some of the lines can be cut without failure of the tether when it is operated near the ultimate failure load of the material from which it is constructed. This tether can safely carry load hundreds of times longer than prior art tethers in harsh environments where a single-line tether experiences a substantial risk of failure. The specific industrial applications of an electrodynamic tether system to deorbit satellites and a low Earth orbit to lunar surface tether transport system are all part of the general innovative concept of the invention.

Abstract: A tether having the special technical feature of multiple primary load-bearing lines and normally slack secondary lines. These primary and secondary lines are connected together with knotless, slipless interconnections so the tether maintains high strength and some of the lines can be cut without failure of the tether when it is operated near the ultimate failure load of the material from which it is constructed. This tether can safely carry load hundreds of times longer than prior art tethers in harsh environments where a single-line tether experiences a substantial risk of failure. The specific industrial applications of an electrodynamic tether system to deorbit satellites and a low Earth orbit to lunar surface tether transport system are all part of the general innovative concept of the invention.

Abstract: A tether having the special technical feature of multiple primary load-bearing lines and normally slack secondary lines. These primary and secondary lines are connected together with knotless, slipless interconnections so the tether maintains high strength and some of the lines can be cut without failure of the tether when it is operated near the ultimate failure load of the material from which it is constructed. This tether can safely carry load hundreds of times longer than prior art tethers in harsh environments where a single-line tether experiences a substantial risk of failure. The specific industrial applications of an electrodynamic tether system to deorbit satellites and a low Earth orbit to lunar surface tether transport system are all part of the general innovative concept of the invention.

Abstract: A tether (FIG. 6) having the special technical feature of multiple primary load-bearing lines (601,603) and normally slack secondary lines (605, 603). These primary and secondary lines are connected together with knotless, slipless interconnections so the tether maintains high strength and some of the lines can be cut without failure of the tether when it is operated near the ultimate failure load of the material from which it is constructed. This tether can safely carry (FIG. 31) load hundreds of times longer than prior art tethers in harsh environments where a single-line tether experiences a substantial risk of failure. The specific industrial applications of an electrodynamic tether system to deorbit satellites and a low Earth orbit to lunar surface tether transport system are all part of the general innovative concept of the invention.

Abstract: The present invention comprises an electrodynamic tether structure and a method of use. The structure of the tether taught by the present invention is a short, wide, interconnected multiwire (compared to the long, narrow single wires of the prior art) conductive tether whose area maximizes electrodynamic drag while simultaneously minimizing the Area-Time-Product swept by the tether during its operating life. The preferred tether length is two kilometers to five kilometers. The preferred tether mass is one percent to five percent of the spacecraft mass. The method of operation comprises orienting the tether structure at an angle to the local vertical to maximize electrodynamic drag on the host spacecraft and minimize tether instability. The angle of 35.26 degrees is preferred.

Abstract: An artificial space object capable of operating usefully adjacent to, but not in orbit about, a celestial body such as the Earth, comprising: payload means for providing useful services from a position in space adjacent to the Earth, light pressure propulsion means for intercepting light pressure and directing the resulting force to oppose the gravitational force between the Earth and the space object; and attachment means for attaching the propulsion system to the payload, whereby the force generated by the propulsion system may be transmitted to payload. The invention is designated a "Statite", i.e. a useful space payload maintained by light pressure in a position adjacent to the surface of a celestial body, but not in orbit around it. The propulsion system may be a solar sail or it may be a solar photon thruster. The useful payload may be the space segment of a communications, broadcasting, remote sensing, or any other useful space system.

Abstract: The damping of vibrations in a mechanical structure is accomplished while minimizing the impact on the design and operation of the structure through the use of a plurality of attachable vibration damping elements. Each vibration damping element contains: an accelerometer, an integrator, mixer, power amplifier, and a force actuator. The accelerometer measures the motion of the vibration in the structure at its attachment point and produces an acceleration measurement signal. The integrator integrates the acceleration measurement signal to produce a velocity measurement signal. The mixer produces a composite motion signal by mixing the acceleration measurement signal with the velocity measurement signal. The power amplifier adjusts the phase and amplitude of the composite motion signal to drive the force actuator to damp the sensed vibration along one dimension at the attachment point of the force actuator.

Abstract: Gimbal ring 32 has torquer positioner 34 and position detector 36 connected by servo loop 38, 40. Vibration sensor 52 on ring 32 provides ring vibration signals to amplifier shifter 54, 58 and the resultant signals are added to the servo loop at amplifier 40 to damp out the detected vibration.

Abstract: An improved photodector which in utilizing a low noise load network instead of a resistor has the advantages in signal-to-noise ratio of a large load resistance without the deleterious effect on response time. The circuit includes a conventional photodiode with an operational amplifier at its output. The load network is disposed in the feedback path of the operational amplifier. It consists of a second operational amplifier, a fixed resistor and a variable resistor.

Abstract: Circuits are described which optimize the signal-to-noise ratio of a signal amplifier by means of active circuits which simulate low-noise resistors. When such "absorbers" or "desorbers," as they are termed, are used in amplifier circuits with signal sources characterized by equivalent thermal noise resistances they provide low-noise means for matching the source and amplifier for optimum noise behavior. In accordance with the invention therefore, it is possible to utilize active circuit elements such as transistors or op-amps in such a way as to realize amplifiers which have better noise figures than conventional amplifiers fabricated of the same circuit elements.

Abstract: A two-terminal active network which simulates a low noise-temperature resistor is disclosed. In a preferred embodiment, a pair of operational amplifiers, each connected in the manner of a "current pump," comprises the active elements of the network. A resistive voltage divider network provides both positive and negative feedback to the operational amplifiers. Simulated resistors can be obtained with a wide range of equivalent resistance values and effective noise temperatures.

Abstract: A class of two-terminal active networks which simulate low-noise temperature resistors is disclosed. A single field effect transistor or other suitable amplifier comprises the active element of the network. A dual transformer feedback arrangement or a single transformer feedback arrangement comprises the remainder of the circuit. Either positive or negative simulated resistors can be obtained with a wide range of equivalent resistance values and effective noise temperatures.

Abstract: Methods and apparatus are disclosed for substantially reducing the effect of the inherent transducer capacitance in a transducer-coupled electromechanical system which is subject to vibrational movement. First and second electromechanical transducers, mechanically coupled to the mechanical structure are interconnected by an electronic feedback network. The feedback network is characterized by very low input and output impedances thus overcoming the shunting effects of the inherent transducer capacitance. In preferred embodiments the feedback network is "electronically cooled" thereby providing low-noise damping.

Abstract: A circuit is disclosed for impedance matching an electrical signal-generating transducer to an electrical signal-processing amplifier while substantially retaining both the original signal-to-noise power ratio and the original signal amplitude at the input to the amplifier. A load resistance of a value substantially equal to twice the characteristic resistance of the transducer is coupled across the amplifier input, while a negative low-noise resistance approximately equal in magnitude to the source resistance is coupled in series with the load resistance. A transmission line having a characteristic impedance approximately equal to the transducer resistance is coupled between the transducer output and the series-coupled load resistance and negative resistance.

Abstract: A class of two-terminal active networks which simulate low-noise-temperature resistors is disclosed. A single differential-input operational amplifier connected with a feedback resistor in an inverting amplifier configuration comprises the active element of the network. A resistive voltage divider feedback arrangement comprises the remainder of the circuit. Either positive or negative simulated resistors can be obtained with a wide range of equivalent resistance values and effective noise temperatures.

Abstract: Arrangements are disclosed for substantially reducing the effect of the inherent transducer capacitance in a transducer-coupled electromechanical system which is subject to vibrational movement. Electrical circuitry is coupled across the transducer output to provide a negative capacitance having a magnitude substantially the same as that of the inherent transducer capacitance, thereby substantially nullifying the inherent transducer capacitance and enabling improved damping (including low-noise damping) to be achieved.

Abstract: A class of two-terminal active networks which simulate low-noise temperature resistors is disclosed. A single differential-input operational amplifier connected with a feedback resistor in an inverting amplifier configuration comprises the active element of the network. A dual-transformer feedback arrangement or a single transformer feedback arrangement comprises the remainder of the circuit. Either positive or negative simulated resistors can be obtained with a wide range of equivalent resistance values and effective noise temperatures.