Orbital Debris Tracking

The rise in spacecraft launches is causing congestion in low Earth orbit (LEO) and higher orbits. The U.S. National Space Policy [1] has focused on orbital debris prevention since 1988, with its 2020 update stating that the United States shall (among others): Develop, maintain, and use Space Situational Awareness information (...) Limit the creation of new debris, (...) Pursue research and development of technologies and techniques to characterize and to mitigate risks from orbital debris , reduce hazards, (...); Evaluate and pursue,(...), active debris removal as a potential long-term approach to ensure the safety of flight in key orbital regimes; Continue to foster the development of best practices to prevent on-orbit collisions. Space situational awareness refers to the knowledge and characterization of space objects and their operational environment to support safe, stable, and sustainable space activities. Space traffic coordination refers to planning, coordinating, and synchronizing on-orbit activities to enhance the safety, stability, and sustainability of operations in space. NASA views orbital debris management as the ability to mitigate the creation of new debris through design and operations, to implement operational procedures for spacecraft to avoid collisions with debris, to protect missions from damage due to strikes of orbital debris, to limit reentry casualty risks, to characterize the populations of debris that are not currently tracked, and to clean up debris through various remediation methods [2]. Space weather awareness regards obtaining knowledge of and predicting the varying natural environment in response to changing solar conditions. The purpose of this sub-topic is to develop a (primarily) ground-based tracking solution that can maintain custody of a piece of small debris from the time it rises above the horizon to the time it descends below the horizon. This solution is primarily intended to support laser removal of orbital debris and to provide near-term improvements to existing space situational awareness (SSA) capabilities. The U.S. economy depends on space for critical infrastructure, from communications and financial exchanges to national security, transportation, and climate monitoring. Orbital debris such as abandoned vehicle stages, non-functional satellites, and fragments of launched materials impedes our ability to use space by increasing the cost of space operations. More than 23,000 pieces of orbital debris are larger than a softball (about 10 centimeters) and tracked by the Department of Defense's global Space Surveillance Network (SSN) sensors. Because the debris is tracked, spacecraft operators can predict conjunctions with this debris and maneuver to avoid potential collisions. However, less than 1 percent of debris objects that could cause damage to a spacecraft are currently tracked and can damage satellites and crewed spacecraft without warning. In the space environment, there are approximately half a million pieces of debris larger than the size of a pea (1 centimeter) and approximately 100 million pieces of debris larger than the size of a grain of sand (1 millimeter). Spacecraft cannot feasibly be shielded from debris that are larger than a few millimeters. Thus, the only feasible approaches to protect spacecraft from this risk are to track them well enough to enable spacecraft to maneuver to avoid them or to remove them altogether [3,4]. Both approaches require the ability to maintain custody of small debris at least as they pass overhead, ideally for multiple revisits. NASA seeks innovative, (primarily) ground-based technologies that could be used to provide the following level of custody: Addresses debris as small as 1 centimeter, in orbits from 350 to 800 kilometers altitude or higher. Acquires custody of the debris as it rises above the horizon, possibly by being tipped with an externally provided orbital solution. Maintains custody of the debris at least until it is directly overhead, but ideally also until it descends below the horizon. In the best case, orbit determination is sufficient to allow for re-acquisition by sensors in other locations. Relevant technologies for this topic include, but are not limited to: Light Detection and Ranging (LiDAR) systems that could maintain custody of such debris. Adaptive optics capabilities for observing and/or delivering pre-compensated beams to fast-moving objects in LEO. Phased-array radar systems that could detect, rapidly perform orbit determination, and maintain custody of such debris. Passive optical or infra-red IR systems if they can maintain custody of such debris in darkness. Space-based and air-based sensor architectures are acceptable, if they can provide orbit determination for a significant fraction of objects in at least one orbital regime (Low Earth Orbit, Medium Earth Orbit, Geostationary Orbit, or lunar orbit).