Enhancing Our National Space Surveillance Assets – Cobra Dane

As a result of our proposed software modifications, Cobra Dane now collects an unprecedented quantity of valuable metric observation data on the smallest and most difficult-to-track objects in the satellite catalog.

Riverside Research is proud of its unrivaled track record of enhancing the mission performance of all the radar systems we support. Our engineering team authored enhancements to the AN/FPS-108 Cobra Dane Radar Mission software that significantly increased the system’s Spacetrack data yield and satellite tasking throughput. These algorithm improvements unlocked inherent but previously inaccessible performance capabilities that were constrained by software designed for an outdated space environment and operating paradigm.

As a result of our proposed software modifications, Cobra Dane collected an unprecedented quantity of valuable metric observation data on the smallest and most difficult-to-track objects in the satellite catalog. Specifically, the daily number of objects tracked increased by 150% of the previous historic performance level. This is coupled with a decrease in ‘retagged’ satellites, marking a significant reduction in the post-event processing required by space data analysts at the Joint Space Operations Center.

Contributions to Cobra Dane Space Surveillance Mission

In April 1994, after the Cobra Dane System Modernization (CDSM) program was completed, budget constraints forced the discontinuation of Cobra Dane’s space surveillance mission, though the radar continued to support its other missions without interruption. As a cost-saving measure, Cobra Dane ran at a limited duty factor during periods of relative inactivity. Based on a Riverside Research recommendation, an “automatic transmitter run-up” capability was also implemented under the operations and maintenance (O&M) effort that ameliorates risk of mission data loss under limited duty operations. Although the space surveillance mission was effectively inactive for five years, the software for space surveillance support remained unchanged and internal system capabilities were preserved (and even regression tested) with each software version release.

In early 1999, under the auspices of the Cobra Dane Program Office and with the close cooperation of the O&M contractor and space data analysts from Air Force Space Command (AFSPC), Riverside Research orchestrated a series of demonstrations of the radar’s inherent but previously untapped space debris tracking capabilities. These demonstrations clearly showed the value of Cobra Dane to AFSPC and NASA. The timing was coincident with final construction phases of the International Space Station (ISS), at a time when increased demand was placed on sensors that could track orbital debris that posed a threat to the ISS and the Shuttle Orbiter flights. Test results revealed that Cobra Dane was the most capable system available to accurately track the large number of small but hazardous objects that evaded the (predominantly UHF) phased array radars in the Space Surveillance Network (SSN). In fact, space analysts evaluating the radar data determined that Cobra Dane was the most accurate phased array radar in the network [1]. In October 1999, following the successful demonstrations, Cobra Dane’s historic secondary mission of space surveillance was restored, albeit at limited duty factor on a non-interfering basis with the radar’s primary mission. A dedicated data link was re-established for automatic data transfer and satellite tasking. Cobra Dane began tracking satellites that had not been observed by the SSN in more than five years since the mission was deactivated, and new objects were continuously being discovered. In March 2003, with additional funding from AFSPC, Cobra Dane resumed near-continuous full power operations, which increased its space surveillance tasking, small-object discovery and data yield. Almost immediately the satellite catalog volume began to grow, with several thousand new objects being uniquely tracked by Cobra Dane. However, limitations remained with the old system operating paradigm and original space-track processing algorithms.

Significant effort was also devoted to helping Spacetrack data users address a growing problem of “lost satellites.” (Lost satellites are defined as those that have not been updated within the past 30 days, and consequently cannot be reliably used for important missions such as collision avoidance.) This concerted effort included a thorough examination of Cobra Dane’s internal Spacetrack mission planning functions and led to the discovery of multiple software performance limitations that contributed to lower than expected tasking success. In addition, the system squandered valuable opportunities to collect metric observations on tasked satellites that were serendipitously acquired via space debris fences. For the majority of its service life, the system was effectively held back by outdated mission software rather than by the radar’s overall architectural design and resource limitations. These software limitations prevented Cobra Dane from applying all of its available (and unused) resources for important space surveillance functions. In short, the system was better configured or ‘tuned’ for its previous Spacetrack support role against the larger (and most widely tracked) orbital objects than for its more modern role in finding and reacquiring small debris, for which the efficient use of radar resources is paramount.

Over the course of this effort, there have been three software versions released under the guidance of Riverside Research, leading to the most significant leap in Cobra Dane’s space surveillance capabilities since the program’s inception. In 2011, Software Version 2.6.7 enabled Cobra Dane to track satellites in the deep space orbital regime for the first time in its operational history, not because the system lacked power and sensitivity, but because it was previously constrained by software. Up until that time, owing to internal software (track filter configuration) limitations, the system was not reporting metric observation data with the full accuracy it was capable of against all Uncorrelated Targets (UCTs). As JSpOC ramped up their efforts to increase the Cobra Dane Spacetrack throughput and minimize the problem of lost satellites, additional internal software restrictions were identified by Riverside Research and addressed in two subsequent software version releases (2.6.8 and 2.6.9). The latest software update (version 2.6.9), provided the most significant mission improvements to date and was the first build to affect the overall operating paradigm of how Cobra Dane performed its Spacetrack mission.

[1] “Analysis of Small Object Tracking Data From the Cobra Dane Phased Array Radar” AFSPC Space Analysis Center Technical Report, 1999.