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Developing Methods for Positional Accuracy of High Resolution Satellites


OBJECTIVE: Increase the pointing accuracy of the Kestrel Eye satellite to 10 meters or less. DESCRIPTION: The United States has very highly capable imaging satellites built by both Government and commercial organizations. However these satellites are expensive, limited in number and there is competition for their use. The Army desires to increase the persistency of imagery coverage, have tasking controlled directly by lower echelons and have imagery delivered from the satellite directly to the tasking forces. There is also a desire to be able to share this imagery with Allies and coalition partners in near real-time. This imagery is used for battlespace awareness purposes, as opposed to technical intelligence. As a result, medium to lower resolution imagery is acceptable if delivered within a few minutes of tasking. The miniature electronics revolution that has made smart phone possible is being extended into space. Very small satellites offer an affordable solution to increasing the number of available apertures on orbit in order to achieve persistent coverage for low organizational levels of mission command. Kestrel Eye is an imaging microsatellite capable of producing visible imagery at 1.5 meter ground sample distance resolution when the satellite is pointed at nadir. Design trades are in work to add an infrared and/or hyperspectral imaging capability. Images that cover an area 5.8 by 3.8 kilometers are transmitted in jpg format with a GPS tag indicating the ground latitude and longitude of the image. The Block II Kestrel Eye design weighs between 22 and 25 kilograms. The satellite has a GPS receiver, a star tracker, and reaction wheels to control pointing. The estimated ground location accuracy of the image is currently about 60 meters. Images from Kestrel Eye will be used to detect the presence of enemy activity, to include the implanting of Improvised Explosive Devices (IEDs). Images will also be used to assist in maintaining perimeter security at our forces"forward operating locations. Some of these images will be in areas where there are insufficient terrain features to precisely locate objects in the frame. This drives the need for improved pointing accuracy. The objective of this SBIR is to improve the pointing accuracy or the ground location accuracy of imagery collected by the Kestrel Eye microsatellite to much better than 60 meters. The technical challenge of this SBIR is that the small size of Kestrel Eye limits the size, weight and power consumption of satellite position sensors, control electronics and the incorporation of position knowledge into the image data being transmitted. Although the satellite is capable of taking five pictures per second, the S-Band downlink rate of 1 Megabit/second limits transmissions to one image approximately every 10 seconds. In addition, the satellite will be flying at a nominal altitude of 450 kilometers, which results in short overhead passes and rapidly changing angles from the telescope to the target site. Despite the extraordinary investment the commercial electronics industry has made in miniaturization and the success achieved with smart phones and other personal electronic devices, this revolution has only just begun to extend into space. The purpose of this SBIR is to accelerate that extension and optimize the application of these technologies into the Kestrel Eye satellite form factor to improve position knowledge of the image from 60 meters to 10 meters or less. PHASE I: Determine the technical feasibility of using miniaturized position sensors, control electronics and data transmission systems to improve the pointing accuracy of Kestrel Eye from 60 meters to 10 meters or better. Perform end-to-end systems engineering to ensure all of the components work in harmony to achieve the desired performance. This research should also present information on a realistic design that would fit within the weight, power and physical space dimensions of the 25 kilogram satellite. PHASE II: Leveraging the results from Phase I, develop a prototype system for Kestrel Eye that can be used in ground verification testing. Simulated orbital conditions will be fed into the sensors and pointing accuracy will be extrapolated based upon test measurements. PHASE III: The end state for this R & D will be an enhanced Kestrel Eye imaging microsatellite that will have provide imagery with greatly improved positional accuracy. This capability will improve the operational awareness of units in the field and will support mission command and intelligence operations. The persistent coverage provided by these enhanced satellites will improve soldier survivability and lethality. Interest in microsatellite imaging technology is rapidly increasing both for National Aeronautics and Space Administration (NASA) as well as commercial applications. Imaging microsatellites are being examined for environmental monitoring as well as use in humanitarian assistance and disaster relief. REFERENCES: 1) US ARMY NANOSATELLITE TECHNOLOGY DEMONSTRATIONS, by John R London III, A. Brent Marley, US Army Space and Missile Defense Command, 2) KESTREL EYE Visible Imagery Nanosatellite Technology Demonstration 3) Space Enabled Effects for Military Engagements (SeeMe)
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