SCHEDULER FOR MONITORING OBJECTS ORBITING EARTH USING SATELLITE-BASED TELESCOPES

• US 20130275036A1
• Filed: 07/26/2012
• Published: 10/17/2013
• Est. Priority Date: 07/26/2011
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Inventors: Olivier, Scot S., Pertica, Alexander J., Riot, Vincent J., De Vries, Willem H., Bauman, Brian J., Nikolaev, Sergei, Henderson, John R., Phillion, Donald W.
• Granted Patent: US 9,020,748 B2
• Time in Patent Office: Days
• US Class Current: 701/301
• CPC Class Codes: B64G 1/1085 Swarms and constellations
• CPC Class Codes: B64G 1/242 Orbits and trajectories
• CPC Class Codes: B64G 1/36 using sensors, e.g. sun-sensors, horizon sensors
• CPC Class Codes: B64G 3/00 Observing or tracking cosmonautic vehicles

Abstract

An ephemeris refinement system includes satellites with imaging devices in earth orbit to make observations of space-based objects (“target objects”) and a ground-based controller that controls the scheduling of the satellites to make the observations of the target objects and refines orbital models of the target objects. The ground-based controller determines when the target objects of interest will be near enough to a satellite for that satellite to collect an image of the target object based on an initial orbital model for the target objects. The ground-based controller directs the schedules to be uploaded to the satellites, and the satellites make observations as scheduled and download the observations to the ground-based controller. The ground-based controller then refines the initial orbital models of the target objects based on the locations of the target objects that are derived from the observations.

Claims

1. A system for generating a schedule for monitoring target objects that are in earth orbit via a network of satellites having imaging devices for collecting images, the system comprising:

a component that receives collision predictions for the target objects;

a component that identifies close approaches of the target objects to satellites;

a component that, for each close approach of a target object to a satellite, determines viewing angles, a collection time, and an expected image quality for collecting an image of the target object by the satellite; and

a component that, for each satellite, adds to a schedule for that satellite a scheduled observation indicating orientation of the imaging device and collection time for close approaches to that satellite with an expected image quality that satisfies an image quality criterion.

2. The system of claim 1 wherein the identified close approach of a target object to a satellite is within a collection window that is prior to the collision time for that target object.

3. The system of claim 2 wherein scheduled observations for a target object are added to schedules to maximize difference in collection times for images of that target object.

4. The system of claim 3 wherein the number of scheduled observations for each target object is less than a threshold number.

5. The system of claim 1 wherein the expected image quality is represented by a signal-to-noise ratio that factors in solar illumination and viewing angle for the target objects.

6. The system of claim 1 wherein scheduled observations are added to schedules for satellites factoring in whether the satellites are available at the collection time of a close approach.

7. The system of claim 6 wherein a satellite is not available when the imaging device of that satellite cannot be oriented as required by the observation.

8. The system of claim 1 including a component that sends the schedules to a transmit device for transmitting the schedules to the satellites.

9. A computer-readable storage Medium containing computer-executable instructions for controlling a computing device to generate a schedule for collecting images of target objects in earth orbit that may collide via a network of satellites having imaging devices for collecting images, by a method comprising:

for each satellite,

identifying close approaches of the target objects to that satellite;

for each close approach of a target object to that satellite, determining viewing angles, a collection time, and an expected image quality for collecting an image of the target object by that satellite;

selecting as observation possibilities for that satellite the close approaches with the highest expected image qualities; and

adding to the schedule for that satellite as scheduled observations the observation possibilities with a collection time during which that satellite is available.

10. The computer-readable storage medium of claim 9 wherein the selecting includes selecting only the observation possibilities with an expected image quality that satisfies an image quality criterion.

11. The computer-readable storage medium of claim 9 wherein the identified close approach of a target object to a satellite is within a collection window that is prior to a time of a predicted collision for the target object.

12. The computer-readable storage medium of claim 9 wherein scheduled observations for a target object are added to schedules to maximize difference in collection times for images of that target object.

13. The computer-readable storage medium of claim 12 wherein the number of scheduled observations for each target object is less than a threshold number.

14. The computer-readable storage medium of claim 9 wherein the expected image quality is represented by a signal-to-noise ratio that factors in solar illumination of the target object and angles between the satellite, the sun, and the target object.

15. The computer-readable storage medium of claim 9 wherein a satellite is not available when the imaging device of that satellite cannot be oriented to the required orientation by the collection time.

16. A method performed by a computing system for generating a schedule for collecting images of target objects in earth orbit that have been identified as having a possibility of colliding with other target objects, the images being collected via a network of satellites having imaging devices, the method comprising:

storing an indication of the target objects that have been identified as having a possibility of colliding with other target objects;

identifying close approaches of the target objects to the satellites; and

for each close approach of a target object to a satellite,

determining an imaging device orientation, a collection time, and an expected image quality for collecting an image of the target object by the satellite; and

adding to the schedule of that satellite a scheduled observation indicating the imaging device orientation and collection time for the close approach when the expected image quality satisfies an image quality criterion.

17. The method of claim 16 wherein scheduled observations for a target object are added to schedules to maximize difference in collection times for images of that target object.

18. The method of claim 16 wherein the expected image quality is represented by a signal-to-noise ratio that factors in solar illumination of the target objects.

19. The method of claim 16 wherein scheduled observations are added to schedules for satellites factoring in whether the satellites are available at the collection time of a close approach.

20. The method of claim 19 wherein a satellite is not available when the imaging device of that satellite cannot be properly oriented at the collection time of the close approach.