NEWS | Dec. 19, 2011

NRL's Dr. John Emmert Appointed to NRC Committee to Assess Air Force Orbit Standards

By Donna McKinney

Dr. John Emmert Of the Naval Research Laboratory's Space Science Division is now serving on a newly convened National Research Council study. The committee is assessing the astrodynamics algorithms that the Air Force uses to maintain a catalog of over 20,000 objects in Earth orbit. Dr. Emmert's expertise is in atmospheric density modeling, which is the largest source of orbit prediction uncertainty for objects in low Earth orbit.

The Air Force commissioned the National Research Council (NRC) to assess the astrodynamic standards established by Air Force Space Command (AFSPC) and their effectiveness in meeting mission performance needs, as well as possible alternatives. The Joint Space Operations Center (JSpOC) uses astrodynamic algorithms to perform satellite orbit determination and prediction in order to maintain a catalog of over 20,000 objects, ranging from active satellites to tiny pieces of orbital debris. AFSPC established this set of astrodynamic algorithms as standards to be used in operational space surveillance mission systems. These standards were implemented to achieve interoperability between the JSpOC and the mission systems and to ensure mission performance.

The NRC Committee will: (1) assess the current AFSPC astrodynamic standard orbit determination and prediction models for accuracy, interoperability, and ability to meet JSpOC and user mission requirements; (2) compare and contrast leading industry, academic, and government alternatives, including benefits and drawbacks, to the current AFSPC astrodynamic standard; (3) outline options for a strategy of how AFSPC should proceed with using these alternate standards to meet JSpOC and user requirements; and, (4) examine broader issues concerning overall cost and risk of the options.

NRL's Emmert, whose research focuses on the climate and dynamics of the thermosphere, has been appointed to this NRC Committee based on his experience in atmospheric density modeling, which is the largest source of orbit prediction uncertainty for objects in low Earth orbit. The Committee also comprises representatives from industry and academia.

The study is scheduled for completion in mid 2012; details of the committee's charter and membership may be found at The National Academies Project Information. The committee's first meeting was held in October in Colorado Springs.