Keith Morris, Lockheed Martin; Holly Flinchpaugh, Lockheed Martin; Rachel Urban, Lockheed Martin
Keywords: Space Situational Awareness (SSA), Space Domain Awareness (SDA), Space-based sensors, CubeSat, geosynchronous earth orbit (GEO)
Abstract:
Lockheed Martin Space has been studying solutions that could better address maneuvering objects at geosynchronous earth orbit (GEO) and provide timely observations following those maneuvers in GEO. Looking at the current architecture, there has been a lot of concern about satellites and their proliferation. The size of CubeSats in particular makes it difficult to track and even more difficult to predict where they are going to be when they change position or come close to another satellite. When you add debris created from launches, decommissioned satellites not in the graveyard orbit, and on-orbit collisions, the result only adds to the increasing need to keep an accurate catalogue of objects and events. Seeing the future move towards proliferation elevates this need to ensure the safety of all domestic and international assets in GEO. Lockheed Martin Space is in the midst of a study that will provide more insight and possible solutions to this foreseen gap.
As satellites get smaller and technology becomes more advanced, it is important to continuously review architectural gaps within SDA. As GEO becomes a more popular orbit for smaller satellites and proliferation, an architecture study was performed to help determine what sensors could be used to effectively track movements in the GEO belt. Traditionally ground-based telescopes are used for these observations; however, space-based sensors such as wide-field of view cameras in proliferation above GEO, would provide more accurate and timely data output. Ground based optical sensors also, generally, have solar exclusion zones and have trouble tracking when the sun is overhead. This can lead to gaps in coverage of the important objects in GEO. Ground based optical systems have a higher sensitivity and their locations are very well known, which helps reduce the orbit error. The expensive sensors should be used to provide observations on many space-based objects instead of focusing on one or two that would create gaps in coverage. Using a combination of Matlab and Systems Tool Kit (STK), the analysis looked at the different basing orbits based on sensor performance as well as the quantities of sensors versus the observation revisit rates. Additional runs were made to study the effects of sensor performance on the constellation size to start optimizing the architecture. It is also important to look at the possible platforms to host these sensors. Hosted payloads are one option that comes with its own set of challenges. For example, securing payload slots on various satellites that will effectively be spread around the GEO belt to cover relevant longitudes is a time and risk consuming approach. Factoring in the timeliness of launches in order to have an up and running constellation is another challenge. On the other hand, CubeSats have become more reliable with maturing technologies that are cost effective. As launch providers drive down the costs, it becomes more realistic to launch many CubeSats at once rather than larger satellite platforms individually. One of the regrets of CubeSats will be their reduced positional accuracy that will reduce the accuracy of the observations.
Based on the analysis performed, a constellation of sensors at GEO capable of being hosted on CubeSats can provide near continuous coverage of the GEO belt to aid in maneuver detection. This in turn will aid in the timeliness of new orbital tracks for the objects that support tactical timelines for Course of Action generation. These sensors can be hosted on CubeSats which enables a more proliferated architecture while driving down the launch and constellation sustainment costs.
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Date of Conference: September 15-18, 2020
Track: Space-Based Assets