Abstract: Existing satellite solar arrays are deployed perpendicular to the satellite so that they rotate to track the daily movement of the sun to increase the solar array's' output power. In the present invention, the solar arrays are biased by a fixed amount away from the orbit perpendicular axis to maximize their minimum output power over the seasons. As the satellite orbits about the earth, the solar array rotates about the orbit perpendicular axis along a conical path so that the array faces towards the sun and maintains its biased attitude with respect to the sun. The biased attitude is preferably selected to equalize the solar array's summer and winter solstice output power minimums, thereby maximizing the worst case output power for a single axis of rotation solar array. The solar array is preferably biased by either forming the shim between the solar array drive mechanism and the solar array with the desired bias or by using the Adjustable Solar Wing Actuator (ASWA) available on certain satellites.

Abstract: An apparatus and method for use thereof in the creating of a nanogravity environment substantially throughout a working volume sufficient for performing a desired operation and existing for a length of time sufficient for performing the desired operation are disclosed. Involved in the creation of the nanogravity environment are the use of an apparatus in which the mass density of the walls are distributed (either directly or by the attachment of compensating masses) so that the surface density of the mass is directly proportional to the electric charge density along the walls which would be sufficient to neutralize the interior electric field, the orbiting of the apparatus around a planetary mass, and the minimization of disruptive accelerations on the apparatus by the selective transfer of the momentum of solar photons to the apparatus.

Abstract: A satellite embodying at least one surface intended mainly for exposure to solar radiation and extending away from the satellite in a predetermined direction (Y), an on board computer having connected thereto an attitude sensing system, an orbit control system for imparting thrust to the satellite along predetermined axes, and an attitude control system. The satellite further embodies a device for controlling the tilt of the surface in parallel with a plurality of planes containing the predetermined direction; and, therefore, particularly in parallel with the plane of a solar panel forming the surface. The tilt control device is controlled by the on-board computer. The tilting can generate a moment of pitch or relocate the center of gravity onto the axis of the orbit control system.

Abstract: A constrained solar array (24) for a satellite (20) and method for making the same are disclosed. The solar array (24) includes a superstructure (30) with solar cells (80) mounted thereon to provide power to a main satellite body (22) and instruments mounted thereon. A flexible tensile member (40) extends relative to the superstructure (30) and is placed under tension to place the solar array (24) in a constrained condition which reduces thermal transients in and increases the bending frequency of the solar array (24). Preferably, a pair of support arms (34,36) are cantilevered from the superstructure (30). The flexible tensile member (40) pulls upon the support arms (34,36) to apply bending moments to the superstructure (30) to maintain the solar array (24) in a distorted shape.

Abstract: Methods for performing attitude maneuvers of a spinning satellite without the use of thrusters, or with a minimal number of thrusters, are disclosed. The attitude maneuvers are primarily achieved through the use of gimballed momentum wheels and solar wing drives. Various maneuvers can be performed depending on whether the satellite has near-zero net momentum or significant net momentum. The maneuvers include sun acquisition, sun hold, Earth acquisition and inversion.

Abstract: The present invention provides a method and system for formationkeeping between two or more orbiting spacecraft by controlling the surface area of the spacecraft facing the direction of perturbative forces acting on the spacecraft. The actual position of each spacecraft is sensed and the distance between the spacecraft is computed. If this separating distance exceeds acceptable tolerances, the affected spacecraft are commanded to change their orientation so that the total surface area facing the direction of motion is altered. Alternatively, the total surface area of the spacecraft facing the direction of solar pressure can be altered. As a result, the forces acting on the spacecraft are altered which alters spacecraft position and velocity. In accordance with another aspect of the invention, surface area variations of individual spacecraft are used to maintain the planar separation between adjacent constellations of orbiting spacecraft at desired distances.

Abstract: The attitude of a satellite placed on a non-heliosynchronous earth orbit in a plane that is inclined relative to the equatorial plane of the earth is controlled for efficient use of solar panels and radiators. The satellite has a structure, solar panels apt to be rotated with respect to the structure rotation and two opposed radiators each fixed on one of two opposed faces of the satellite structure which are orthogonal to the rotation axis. One of the radiators has greater emissivity than the other. A yaw axis bound to the structure satellite and orthogonal to rotation axis is aimed towards the earth. The solar panels of the satellite are maintained in an optimum orientation relative to the sun by rotating them. At least during periods of each year when an angle .beta.

Abstract: Solar tabs are provided which have thermal emissivity and absorptivity properties designed to increase the attitude-control torques that can be generated with rotatable wings in a spacecraft. These increased torques enhance the ability to offset attitude-disturbance torques which typically tend to alter the attitude of a spacecraft from a desired attitude. The tabs include highly absorptive and nonemissive front faces, highly emissive back faces and a high thermal conductivity between the front faces and the back faces.

Abstract: A method of simultaneously performing a translational maneuver of a spacecraft by a thruster and dumping momentum from the spacecraft during a time period P. The method entails aligning the thruster along a thrust vector which is fixed during the time period P, wherein the thrust vector is aligned with the center of mass of the spacecraft at a time P/2, and firing the thruster throughout the time period P.

Abstract: An automatic, on-board system for orbiting spacecraft that controls yaw excursions caused by solar torques and thruster firings, which system combines inputs indicative of roll and yaw momentum increases and inputs containing information comprising the unbiased roll error from the earth sensor, yaw momentum measured from the wheel speeds, and commanded yaw momentum output from the wheel controller, and produces therefrom output signals indicative of the yaw estimate and the yaw momentum estimate. These output signals are combined and processed in a controller with a mimimum yaw error and roll thrust yaw controller gain and a miminmum yaw error and roll thrust yaw momentum controller gain, and a signal is produced therefrom for commanding roll thruster firings to change roll momentum, and, in turn, control yaw attitude and yaw excursions.

Abstract: A geostationary satellite includes a three-axis stabilized body including an onboard computer and at least one solar generator wing extending in a longitudinal direction from the body and coupled to the body by a drive system controlled by the onboard computer and adapted to rotate the wing at least about its longitudinal axis. The satellite further comprises a static radar surveillance device including at least one antenna formed of elementary plane radiating patches and adapted to scan at least part of the space surrounding the satellite body.

Abstract: A method for adjusting the orientation and for compensating interfering torques via solar pressure torques for a satellite moving on an orbit around the earth. The satellite has two solar generators arranged symmetrically on opposite sides of a main body of the satellite. The two solar generators are rotatable independently of one another via servomotors about a first axis of rotation orthogonal to an orbiting plane of the satellite when the position of the satellite is correct. The method comprises the step of: optionally generating solar pressure torques about at least one of three space axes oriented orthogonally with respect to one another, as a result of an adjustment of the solar generators by a targeted rotation about second axes of rotation orthogonal to the first axis of rotation or about the first axis and the second axes of rotation, with respect to a nominal orientation in which the solar generator's normals to surfaces are precisely aligned in the direction of the sun.

Abstract: An air vehicle that includes a body lower portion, a body intermediate portion, body lower portion, a solar panel, elevating apparatus, gimbling apparatus, and inflatable landing gear. The body lower portion has a body lower portion outer surface and contains a body lower portion chamber. The body intermediate portion has a body intermediate portion upper surface and contains a body intermediate portion chamber. The body intermediate portion is connected to the body lower portion. The body upper portion contains a body upper portion chamber and is displaced a distance above the body intermediate portion. The solar panel has a solar panel outer surface and contains a solar panel void. The solar panel connects the body upper portion to the body intermediate portion. The elevating apparatus raises and lowers the air vehicle and is disposed within the body upper portion chamber.

Abstract: A method for operating an orbiting spacecraft includes the steps of (a) changing a mass distribution of the spacecraft from a first mass distribution for setting a first principal moment of inertia of the spacecraft along a first axis approximately equal to a second principal moment of inertia of the spacecraft along a second axis, thereby minimizing a gravity gradient torque about a third axis; (b) performing a desired activity while the gravity gradient torque about the third axis is minimized; and (c) resetting the mass distribution back to the first mass distribution at a completion of the desired activity. The spacecraft includes a plurality of solar array panels, and the step of changing is accomplished by varying a position of at least two of the solar array panels away from a sun-pointing configuration. Also disclosed is a method for stabilizing the spacecraft to resist a rotation about an axis by varying the positions of solar array panels.

Abstract: A satellite stabilized about a roll axis, a yaw axis and a pitch axis, for travel on an orbit with geocentric pointing towards a heavenly body, embodying a body and a solar generator adapted to collect solar radiation, characterized in that the generator includes a single wing supported in a medium portion by an arm extending at least approximately along the yaw axis away from the heavenly body, the arm being connected to the body by a single rotation mechanism with a single rotation axis substantially parallel to the yaw axis, the wing having a constant inclination .alpha. to the yaw axis.

Abstract: A satellite embodying at least one surface intended mainly for exposure to solar radiation and extending away from the satellite in a predetermined direction (Y), an onboard computer having connected thereto an attitude sensing system, an orbit control system for imparting thrust to the satellite along predetermined axes, and an attitude control system. The satellite further embodies a device for controlling the tilt of the surface in parallel with a plurality of planes containing the predetermined direction; and, therefore, particularly in parallel with the plane of a solar panel forming the surface. The tilt control device is controlled by the onboard computer. The tilting can generate a moment of pitch or relocate the center of gravity onto the axis of the orbit control system.

Abstract: A satellite stabilization system compensates for the destabilizing torque introduced by solar radiation pressure by the emplacement of tabs of material angled relative to the back surfaces of the antenna reflectors to intercept solar rays. The material of the tabs interacts with the solar radiation in substantially the same manner as the interaction of the material on the back surface of each antenna reflector to produce a radiation pressure and consequential increment in a torque about an axis of the satellite. Each of the tabs is constructed in the manner of a plate or disk, and is attached by means of a spring mount to the back surface of one of the reflectors. The reflectors are angled relative to each other, as well as to a body of the satellite which holds feeds for illuminating the reflectors, for directing beams of radiation from the feeds towards the earth.

Abstract: A satellite embodying at least one surface intended mainly for exposure to solar radiation and extending away from the satellite in a predetermined direction (Y), an on-board computer having connected thereto an attitude sensing system, an orbit control system for imparting thrust to the satellite along predetermined axes, and an attitude control system. The satellite further embodies a device for controlling the tilt of the surface in parallel with a plurality of planes containing the predetermined direction; and, therefore, particularly in parallel with the plane of a solar panel forming the surface. The tilt control device is controlled by the on-board computer. The tilting can generate a moment of pitch or relocate the center of gravity onto the axis of the orbit control system.

Abstract: A method and apparatus for balancing environmental disturbance torques acting upon a satellite (10) by tilting the satellite solar panels (14,16) toward or away from the sun to change the solar pressure acting upon the satellite (10) as well as the gravity gradient torque generated by different panel (14,16) tilt angles. By balancing the disturbance torque acting upon the satellite (10), satellite disturbances are minimized so that the satellite stabilization system can be made smaller and fuel used for satellite attitude control is minimized. Torque balancing is accomplished at the beginning of the mission through a linear actuator (37) at the mounting location of each solar panel (14,16) to the satellite main body (12) and, once set, is passive and does not require continuous active satellite control.

Abstract: Electrochromic devices are applied to selected areas on a spacecraft. Radiant energy characteristics of the electrochromic devices are altered by applying appropriate electrical excitation signals to the devices to create a force on the spacecraft due to light impinging on the devices sufficient to alter the orientation thereof or maintain it under the action of external disturbance forces or torques.

Abstract: A solar cell voltage regulating arrangement which is particularly advantageous for use in spacecraft includes a light valve such as a liquid crystal cell disposed before the solar cell, to thereby controllably vary the light transmission to the solar cell. A control arrangement varies the transmission of the liquid crystal to control the output voltage.

Abstract: This invention discloses a method for maintaining a desirable orientation of the solar wings of an orbiting satellite (10) relative to the sun. A dual array of sun sensors (26,28) is positioned on a body (12) of the satellite (10) in order to get a measurement of the position of the sun relative to the body (12) once per every orbit of the satellite (10). In addition, an estimate of the position of the solar wings (16,17) relative to the body (12) of the satellite (10) is attained. The sun-to-body angle is then subtracted from the body-to-wing angle to drive an error signal which is applied to a wing driver mechanism in order to maintain the solar wings (16,17) of the satellite (10) in a proper orientation relative to the sun.

Abstract: A spacecraft thermal disturbance control system for controlling the torque exerted on the main portion of a spacecraft as a result of a thermal gradient being applied to a portion of the spacecraft that projects from the spacecraft's main portion. The spacecraft thermal disturbance control system includes a network of distributed temperature sensors located on the surfaces of the projecting portion of the spacecraft, a microcomputer operatively connected to the temperature sensors for receiving temperature information from the temperature sensors and a reaction wheel assembly operatively connected to the microcomputer. The microcomputer provides command signals to the reaction wheel assembly based upon temperature information received from the temperature sensors to cause the reaction wheel assembly to generate a torque that counteracts the torque exerted on the main portion of the spacecraft as a result of the thermal gradient applied to the projecting portion of the spacecraft.

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: A satellite adapted to be stabilized in terrestrial orbit by rotation about an axis oriented at least approximately NORTH-SOUTH has on its external wall a solar generator composed of a plurality of columns of solar cells divided into groups adapted to supply at least one given electrical voltage. In each of a plurality of groups equi-angularly distributed in the circumferential direction, the cells straddle two columns electrically connected by at least two electrical connections forming with the group(s) to which the connection belong an electrical loop. The clockwise or counterclockwise direction of current flow is the same for least the majority of the electrical loops and is so chosen that, at any time, the loops which are illuminated at this time by the Sun, by virtue of interaction with the terrestrial magnetic field, produce a compensating torque in the opposite direction to the solar radiation pressure torque.

Abstract: A method to control the attitude in roll (X) and in yaw (Z) of a satellite including two solar generator panels adapted to be oriented independently of each other about a pitch axis. In a preliminary stage: two geometrical axes x and z are selected in the plane of the roll and yaw axes, there being associated with the z axis a tolerable command torque error much lower than for the x axis, and a correlation law is established between satellite panel depointing angles .gamma..sub.N and .gamma..sub.S and possible command torques due to solar radiation pressure.

Abstract: An attitude control device for a satellite stabilized on three axes including a pitch axis comprises two solar generator wings extending in opposite directions away from a satellite body on respective longitudinal axes at least approximately parallel to the pitch axis. Two drive motors drive these wings independently of each other in rotation about rotation axes at least approximately parallel to the pitch axis to keep the wings facing the Sun with a depointing angle at most equal to a predetermined maximum depointing value. Sensors measure attitude angles and a computation system commands the drive motors according to the attitude angles. On each wing an additional surface in the form at least one vane extends longitudinally beyond the end of the wing parallel to its longitudinal axis. These additional surfaces have substantially the same surface area and are inclined about this axis relative to the wings in opposite directions by at least approximately the same angle which is less than the 90.degree.

Abstract: A method for achieving satellite (24) attitude stabilization against the undesired influences of solar pressure or other attitude disturbances to be used with earth-orbiting satellites of the type employing two solar collection panels (30a), (30b) extending from the satellite body in generally opposite directions (36), (38). Synchronized simultaneous movement of both solar panels about their normal sun-tracking position causes desirable torques to be generated which have a cancelling influence on the undesired satellite movement caused by solar pressure or other attitude disturbances.

Abstract: Device and method for aiming a space probe toward a celestial body. It comprises a solar sail (30, 31) having an asymmetry about an axis (Z) and which subjects the probe (S) to a tilting torque of solar pressure. A kinetic wheel (20) turns about a perpendicular axis (X). This results in a rotation of the probe about the axis perpendicular to the two preceding axes (Y). The rotational speed of the wheel (20) is varied by a control system (23, 24) in order to change the rotational speed of the probe.Application of the invention is to space probes that lie in the plane of the ecliptic.

Abstract: Satellite is maintained in the geostationary orbit about the equator by use of solar sails. These solar sails are oriented to use the sun's radiation pressure to sail the satellite in a first direction for a first portion of the orbit and in a second opposite direction during a second portion of the orbit to counteract the forces tending to pull the satellite out of its equatorial orbit.

Abstract: For controlling nutation of a three-axis stabilized satellite, the angular speed of a solar panel carried by the satellite is selectively and temporarily varied about an average value for modifying the inertia cross-product thereof and generating an angular momentum transverse to the angular momentum present in said body with a phase with respect to the nutation motion which tends to decrease the amplitude of the nutation motion.

Abstract: A spacecraft is adapted for orbital flight in two alternative modes, referred to as the earth-oriented and quasi sun-oriented modes. The spacecraft comprises a spacecraft body, at least one solar array extendible outwardly from the spacecraft body, passive attitude control means utilizing gravity gradient stabilization means which is extendible and retractable relative to the spacecraft body, and active attitude control means. The gravity gradient stabilization means is effective when extended to stabilize the spacecraft in the earth-oriented mode, and the active attitude control means is effective to stabilize the spacecraft in the quasi sun-oriented mode.

Abstract: An orbiting satellite system includes an asymmetrically deployed antenna and two deployable solar cell arrays. The solar cell arrays are deployed to a location which compensates for the asymmetry of the antenna so that the resulting station keeping thruster torques balance. Also, the system surfaces may be configured and the arrays so deployed to balance solar pressure torques on the system.

Abstract: The attitude control is provided under utilization of the solar wind in that the effective surface area of solar panels facing the sun is controlled in accordance with certain rules of asymmetry and under utilization of pulling cable so that an imbalance in received solar pressure is utilized to change the attitude of the satellite.

Abstract: Device for aligning the roll axis of a rotating artificial satellite having radial solar panels equipped with angularly movable control surfaces at their extremities. The device includes a motor associated with each control surface for controlling the angle of the control surface with respect to the solar panel, each motor being actuated by a current which is dependent on the displacement of the roll axis from a desired position and which varies cyclically during the rotation of the satellite. The motor also includes a detector for detecting the angular speed of movement of the control surface and introducing a damping effect.

Abstract: The torque from differential solar pressure acting on a spinning spacecraft body and tending to tilt the spacecraft about an axis transverse to the spin axis, is reduced or eliminated by shifting the center of gravity of the spacecraft axially or longitudinally of the spin axis in a direction toward the center of solar pressure.

Abstract: A sun-sensing guidance system (10) for high-altitude aircraft (A) characterized by a disk-shaped body (14) mounted for rotation aboard the aicraft in exposed relation to solar radiation and having a plurality of mutually isolated chambers (28a, 28b, 32a, and 32b); each chamber of the plurality being characterized by an opening having a photosensor (34a, 34b, 36a, and 36b) disposed therein and arranged in facing relation with the opening for receiving incident solar radiation and responsively providing a voltage output, said photosensors being connected in paired relation through a bridge circuit (38) for providing heading error signals in response to detected imbalances in intensities of solar radiation incident on the photosensors of either pair of photosensors until a nulled relationship is achieved for the disk (14) to the source of radiation.

Abstract: The position and attitude of a spacecraft is modified by selectively adjusting the positions of panels and vanes extending from the spacecraft body, relative to the direction of the ambient solar radiation.