Space Systems/loral, LLC

Other

Korea Aerospace Research Institute

Ahmed A Kamel

Walter S Gelon

Sun Hur-Diaz

Thomas J Holmes

Kam K Chan

Keith J Reckdahl

Darren R Stratemeier

Xen Price

Donald W Gamble

Thomas Randolph

Mark D McLaren

Dochul Yang

Jonathan Sheffield

Chulmin Park

Jin Woo

Handol Kim

Kwok M Ong

Provided is an apparatus for geometrically correcting an image from a geostationary remote sensing satellite, the apparatus being configured to perform the image navigation and registration on image data from a geostationary remote sensing satellite. The apparatus includes the landmark determination part configured to acquire landmark information associated with a first image and the navigation filter configured to calculate a state vector for correcting at least one of the attitude error, the orbit error, and the payload misalignment error with respect to the first image based on the landmark information.

Apparatus and method for image navigation and registration of geostationary remote sensing satellites

A novel Parametric Systematic Error Correction (ParSEC) system is disclosed which provides improved system accuracy for image navigation and registration (INR). This system may be employed in any suitable imaging system and, more specifically, to all imaging systems that exhibit systematic distortion. The ParSEC system may be employed to any such system regardless of sensing type (remote or in situ) or imaging media (photon or charged particle) and is further applicable to corrected imaging of any celestial body currently detectable to remove distortion and systematic error from the imaging system employed. The ParSEC system of the instant invention comprises a software algorithm that generates at least about 12 correction coefficients for each of the INR system measurements such as stars, visible landmarks, infrared (IR) landmarks and earth edges. An iterative estimation algorithm such as, for example, least squares or Kalman filters may be employed to determine the at least about 12 correction coefficients from each set of measurement residuals. The improved image products provide more accurate weather forecasting such as wind velocity and temperature.

Image navigation method using parametric systematic error correction

A practical orbit raising method and system wherein a satellite quickly escapes the Van Allen radiation belts and payload mass and mission life are maximized. A satellite is launched that contains high thrust chemical propulsion thrusters, high specific impulse electric propulsion thrusters and a solar array. The satellite quickly escapes the Van Allen radiation belts by firing the high thrust chemical propulsion thrusters at apogees of intermediate orbits, starting from the transfer orbit initiated by a launch vehicle, to successively raise the perigees until the perigee clears the Van Allen radiation belts. The payload mass and mission life are maximized by firing high specific impulse electric propulsion thrusters to raise the satellite to near synchronous orbit, while steering the thrust vector and solar array to maintain the sun's illumination on the solar array. The chemical and/or electric propulsion thrusters are then fired to achieve geosynchronous orbit.

Practical orbit raising system and method for geosynchronous satellites

A practical stationkeeping method and apparatus wherein an electric propulsion system on a satellite is used to correct north-south drift and the majority of east-west drift which is caused by orbital eccentricity growth. A chemical propulsion system on the satellite is used to correct the remainder of east-west drift due to the growth of orbital semimajor axis. The method and apparatus eliminate the need for additional electric thruster burns in case of an electric thruster failure and therefore eliminates associated power and mass penalties.

Practical method and apparatus for satellite stationkeeping

A spacecraft, such as a geosynchronous weather or communications satellite, is constructed to include a plurality of low thrust thrusters mounted at predetermined locations on at least one of a spacecraft appendage or a spacecraft bus. The plurality of low thrust thrusters are fired in pairs for at least one of removing a disturbance torque or providing fine pointing attitude control. In one embodiment the low thrust thrusters are mounted on a solar array panel, thereby increasing the moment arm and enhancing the thrust output of the low thrust thrusters. In one embodiment a spacecraft has a plurality of low thrust thrusters arranged as at least two sets of two low thrust thrusters, individual ones of the low thrust thrusters of a set being disposed in a V-configuration and mounted at predetermined locations on at least one of a spacecraft appendage or a spacecraft bus. The plurality of low thrust thrusters are selectively fired for achieving control of 3-axes of spacecraft attitude or momentum.

Spacecraft attitude control system using low thrust thrusters

A method and system is disclosed for imaging a celestial object, typically the Earth, with a spacecraft orbiting the celestial object. The method includes steps of (a) operating an imager instrument aboard the spacecraft to generate data representing an image of the celestial object; (b) processing the image data to derive the location of at least one predetermined landmark in the image and a location of edges of the celestial object in the image; and (c) further processing the detected locations to obtain the attitude of the imager instrument. The method includes a further step of outputting the image and the imager instrument attitude to at least one end-user of the image, and/or using the imager instrument attitude to revise the image before outputting the image to the at least one end-user of the image. The generated data preferably represents a one half frame image, and the steps of processing and further processing thus occur at a one half frame rate. The step of processing includes a step of applying the a priori knowledge of the attitude coefficients in processing new observations to determine the imager current attitude.

Satellite camera attitude determination and image navigation by means of

An onboard star tracking system is used to provide continuous attitude and orbital position data independent of the image generating instruments. Such data is instantaneously and continually supplied to the onboard computer which translates such information into mirror position coordinates which is added to the mirror position set based on estimated data from the ground control. An error signal is generated which is used to further adjust the position of the mirror.

Satellite imaging control system for non-repeatable error

A precise, spacecraft camera image navigation and registration system and method wherein a computer 36 on-board the spacecraft and a ground system comprising at least two ground stations precisely compute image navigation and registration data from precise data measurements. The computer on-board the spacecraft (spacecraft control system) uses precise star tracker, gyro, and earth sensor attitude data to precisely point the spacecraft and the camera. The ground system utilizes precise star measurement data from the camera and range data from the ground stations time tagged with GPS precise clock data. The ground system uses these precise measurements to determine precise orbit and attitude coefficients and uploads these coefficient to the spacecraft. The computer on-board the spacecraft uses these precise coefficients to generate and apply precise signals to compensate for slow orbit and attitude variations and register camera images in real time. The computer on-board the spacecraft is also used to generate camera commands to eliminate the need to upload a large number of daily ground commands, which therefore simplifies ground operations.

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Los Altos, CA, United States of America

Ahmed A Kamel