821 results about "Natural satellite" patented technology

Disclosed herein is a system for rapidly resolving position with centimeter-level accuracy for a mobile or stationary receiver [4]. This is achieved by estimating a set of parameters that are related to the integer cycle ambiguities which arise in tracking the carrier phase of satellite downlinks [5,6]. In the preferred embodiment, the technique involves a navigation receiver [4] simultaneously tracking transmissions [6] from Low Earth Orbit Satellites (LEOS) [2] together with transmissions [5] from GPS navigation satellites [1]. The rapid change in the line-of-sight vectors from the receiver [4] to the LEO signal sources [2], due to the orbital motion of the LEOS, enables the resolution with integrity of the integer cycle ambiguities of the GPS signals [5] as well as parameters related to the integer cycle ambiguity on the LEOS signals [6]. These parameters, once identified, enable real-time centimeter-level positioning of the receiver [4]. In order to achieve high-precision position estimates without the use of specialized electronics such as atomic clocks, the technique accounts for instabilities in the crystal oscillators driving the satellite transmitters, as well as those in the reference [3] and user [4] receivers. In addition, the algorithm accommodates as well as to LEOS that receive signals from ground-based transmitters, then re-transmit frequency-converted signals to the ground.

The invention belongs to the satellite navigation and positioning technical field and discloses a low earth orbit satellite-based satellite-earth differential real-time precise positioning method. A low earth orbit satellite is utilized to broadcast the observation data and real-time orbit data of the satellite-borne GNSS (Global Navigation Satellite System) receiver of the low earth orbit satellite to the ground; and after receiving the differential information broadcasted by the low earth orbit satellite, a ground receiver generates a double-difference observation value consisting of the differential information and a local GNSS observation value and performs pseudorange-based moving base station DGNSS (Differential Navigation Satellite System) positioning and carrier phase-based moving base station RTK (Rea-time kinematic) positioning. According to the positioning method of the invention, the global mobile low earth orbit satellite platform is adopted as a reference station, so that real-time precision differential positioning service in the whole world can be realized, and the method does not depend on the distribution of ground reference stations; and a user can realize differential real-time precise positioning just through using a single receiver, and therefore, the method is free of operating range restrictions, and data communication links are not required to be considered.

Various embodiments of the present invention include an attitude control system for use with small satellites. According to various embodiments, the system allows rapid retargeting (e.g., high slew rates) and full three-axis attitude control of small satellites using a compact actuation system. In certain embodiments, the compact actuation system includes a plurality of single-gimbaled control moment gyroscopes (SGCMG) arranged in a pyramidal configuration that are disposed within a small satellite.

The invention relates to a novel imaging method in agile satellite maneuvering, which is capable of realizing imaging of satellite during a posture adjustment process. The method comprises the following steps: according to geographic latitude and longitude of on-board orbit forecast data and imaging object point, a triaxial attitude angle directional target imaging start point of satellite is arranged; a roll angle and a pitch angle are obtained through a modeling algorithm for determining the satellite optical axis directional target imaging point; establishing a CCD image plane in a satellite model, performing calculation to obtain image motion velocity vector and a drift angle through projection calculating, and yaw angle of the satellite is controlled for correcting the drift angle, calculating the image motion velocity vector to obtain TDICCD integration time for image motion compensation, and satisfying the image processing requirement of imaging in maneuvering. The design method is capable of using in a triaxial attitude maneuvering process of the satellite for starting optical payload for a dynamic imaging technology for imaging, so that target directional requirement and image processing requirement during an imaging process can be realized.

A configuration for a satellite constellation has a plurality of planes, each plane including a plurality of satellites therein, at least some of the planes situated at a different altitude than other of the planes. In some embodiments, all planes contain the same number of satellites; in some other embodiments, at least one plane includes a different number of satellites than the other planes in the constellation. In some embodiments, the satellites in each plane are evenly spaced.

The invention provides a novel, low-cost, spin-stabilized lander architecture capable (with appropriate system scaling tailored to the attributes of the target) of performing a soft-landing on a solar-system body such as Earth's Moon, Mars, Venus, the moons of Mars, Jupiter, Saturn, Uranus and Neptune, selected near-Earth and main-belt asteroids, comets and Kuiper belt objects and even large human-made objects, and also moving about on the surface of the target solar-system body after the initial landing in movement akin to hopping.

Locating satellites (e.g., GPS) are culled into a sub-plurality based largely on dwell time within an inverted cone above a relevant site in communication with a wireless device. A first inverted cone having a first base angle is defined above a first site, a second inverted cone having a second base angle is defined above a second site. If the second site is farther from an equator of Earth than the first site, then the second inverted cone is made to have a base angle larger than a base angle of the first inverted cone. If the first site is farther from the equator of Earth than the second site, then the first inverted cone is made to have a base angle larger than a base angle of the second inverted cone. The span of the inverted cone over the site closest to the equator may be limited.

The invention relates to an autonomous orbit control method for a stationary orbit satellite, belonging to the technical field of autonomous orbit control of the satellite. The autonomous orbit control method can be applied to a long-term operation management task of the stationary orbit satellite. After the satellite goes beyond a specified error box in east-west direction or south-north direction, corresponding autonomous orbit maintenance is required to be performed; and meanwhile, by considering the regularity for drift of the satellite along a stationary orbit and error of an autonomous navigation result, the effectiveness of control quantity and the rationality of time interval between every two control processes are required to be judged at each time when the orbit control quantity of the autonomous orbit, i.e., control impulses in the south-north direction and the east-west direction which are delta VNS and delta VEW respectively, are calculated. The method has been successfully applied to china satellites; a remote sensing result shows that the autonomous control strategy of the satellite is correct; and the method can be widely applied to all geostationary orbit satellites required to have the autonomous function.

A satellite and an arrangement for placing the satellite in a retrograde orbit, i.e. inclined at approximately 180° to the equator. Multiple satellites may be used and the orbits thereof may be circular or elliptical. The invention is well-suited for an illustrative satellite inspection application. In this embodiment, the system includes one or more satellites; means disposed on each satellite for receiving electromagnetic energy from objects (e.g. satellites) within a field-of-view thereof; and an arrangement for placing the inspection satellites in a retrograde orbit. The satellites may be equally spaced in a single orbit or disposed in equally spaced orbits. The satellites may include a variety of instruments including radar, infrared, visible, etc. In a radar implementation, the satellite may include a bistatic or (with a transmitter) monostatic radar system. In the bistatic case, the signal may be transmitted from a ground-based or space based platform.

A system and method for navigation utilizes sources of modulated celestial radiation. A spacecraft, satellite, or other vehicle (12) has one or more modulated radiation sensors (22a-22x) mounted thereto for detecting a modulated signal (14) generated by one or more pulsars or other celestial objects (16). A timer (24) measures the pulse time of arrival at a respective pulse sensor (22a-22x) by comparing the pulse signal (14) with a known pulse profile, and a processor (30) calculates a timing difference between the measured pulse time of arrival at sensor (22a-22x) with a calculated pulse time of arrival at a selected reference point (100). The positions and pulse profile characteristics of the pulsars (16) are stored in a digital memory (34) and combining the calculated time difference with the known positions of pulsars (16), the navigational parameters, such as position, velocity, and attitude, for spacecraft (12) with respect to the selected localized reference point (100) can be calculated.

A constellation of satellites may include a plurality of satellites in each of two or more different orbits. Satellites in a given orbit may operate in pairs, flying in tandem, one satellite leading, the other trailing closely behind, to be positioned to image the same target(s) of interest with substantially the same orientation (geographical coincident) at substantially the same time (temporally coincident). The first satellite may acquire SAR data, determine a location of a target of interest, assess cloud cover, and based on an extent of cloud cover, can acquire additional SAR data or cause the second satellite to capture optical imaging data (e.g., cross-cueing). Selection of orbits can provide a relatively high revisit rate may be obtained, allowing frequent opportunities to image given locations on a planet (e.g., Earth). One or more ground stations communicate with the constellation of satellites, and inter-satellite communications may be employed.

A satellite constellation system, including a plurality of satellites in relatively close proximity to each other so that line-of-sight communications can be maintained at all times between adjacent satellites. The satellites are in closely-spaced orbits with incremental offsets in their starting true anomalies to create a pattern of the satellites which is serpentine in nature, moving north and south through latitudes covered as a result of the selected inclination angle while moving also in a longitudinal direction so that the serpentine pattern moves across most ground regions of interest. The constellation is asymmetric in nature in order to maximize the continuous access time. It is also possible to have multiple symmetrically-located constellations of this type.

The invention discloses a child-mother satellite space debris clearing platform. The child-mother satellite space debris clearing platform includes a plurality of child satellites for clearing space debris; each child satellite is detachably connected the same mother satellite; the mother satellite is used for driving the child satellites to move among a multiple pieces of space debris; a space debris clearing device is arranged on each child satellite; and each space debris clearing device includes a child measurement device for measuring a pose of the space debris and a child satellite capturing device. A microsatellite is used as the mother satellite, and a plurality of micro-nano satellites are used as the child satellites; operations such as orbit transferring, closing and detailed survey, and capturing and de-orbiting can be completed coordinately; the child-mother satellite space debris clearing platform is low in cost, is fast in response speed, and is high in reliability; after the child satellites are released, the combined space debris observation network can acquire accurate debris pose information through coordinate observation; and the child satellites can independently complete de-orbiting operations, the mother satellite can directly go to next space debris to be cleared, time and energy can be saved, the benefits of space debris clearing can be increased, and the cost is reduced.

A satellite positioning-based guidance system and method that utilize a simulated inertial navigation system are disclosed. The trajectory of the body of a non-thrusted flight vehicle is used instead of a conventional inertial navigation system. The attitude of the flight vehicle is determined using a satellite receiver, and the Extended Kalman filter is used to implement the navigation function.

A method of and apparatus for determining and controlling the inertial attitude of a spinning artificial satellite without using a suite of inertial gyroscopes. The method and apparatus operate by tracking three astronomical objects near the Earth's ecliptic pole and the satellite's and/or star tracker's spin axis and processing the track information. The method and apparatus include steps and means for selecting preferably three astronomical objects using a histogram method and determining a square of a first radius (R₁²) of a track of a first astronomical object; determining a square of a second radius (R₂²) of a track of a second astronomical object; determining a square of a third radius (R₃²) of a track of a third astronomical object; determining the inertial attitude of the spin axis using the squares of the first, second, and third radii (R₁², R₂², and R₃²) to calculate pitch, yaw, and roll rate; determining a change in the pitch and yaw of the artificial satellite; and controlling on-board generated current flow to various orthogonally-disposed current-carrying loops to act against the Earth's magnetic field and to apply gyroscopic precession to the spinning satellite to correct and maintain its optimum inertial attitude.

The invention relates to a super-close optimized collision-avoidance proximity method for a failure satellite, and belongs to the technical field of spacecraft encounter. An object, namely the failure satellite, is designed into an envelope model in the sphere and ellipsoid combined form to simplify configuration of the object; posture rolling of the object is considered, a relative dynamic model of the object and a tracked star as well as constraints of the path of the tracked star are derived in the dynamic object system; positional nondeterminacy caused by navigation and measurement errors is considered, and the flight forbidden area of the tracked start is further broadened by combining the collision possibility problem; and a safe collision avoidance path is planned on the basis of the Gauss pseudospectral method, and closed-loop feedback control is carried out. According to the invention, spatial limitation in super-close proximity are considered, and requirements for a safe collision free task can be met; and the posture coupling feature of a close proximity spacecraft is emphasized, and whether the distance between the aircrafts satisfies the constraints can be directly determined.

The invention provides a multi-satellite navigation system compatible GNSS (Global Navigation Satellite System) signal receiving method which supports the receiving of satellite signals of a GPS (Global Position System), a GLONASS (Global Navigation Satellite System), a Big Dipper navigation system and a Galileo satellite navigation system at present. The invention also discloses a multi-satellite navigation system compatible GNSS signal receiving correlator which comprises N multi-system correlated channels, wherein each multi-system correlated channel mainly comprises a carrier numerical controlled oscillator (NCO), a code NCO, a pseudo-random code generator and an integrating and zero clearing module; each code NCO is used for outputting a pulse sequence for triggering the pseudo-random code generator and also generating square signals with the same rate as subcarrier signals in a BOC (1, 1) signal demodulation mode; each pseudo-random code generator can generate 14 grades of pseudo-random codes at most; and each integrating and zero clearing module has an overflow protection function and improves the reliability. The multi-satellite navigation system compatible GNSS correlator can be compatible with four satellite systems, effectively improves the reliability and the continuity of navigation and positioning and obviously reduces the use risk of single-system navigation.