Aerodynamic drag is the major perturbation for low earth-orbiting spacecraft. Neutral density is the main contributor to drag for low-orbiting satellites. A variety of empirical models has been developed to provide the engineering and science communities with a capability to specify and predict satellite drag. The proliferation of these models and tailoring by various groups make data comparisons between different agencies difficult. The AIAA Astrodynamics Standards Committee has tasked the AIAA Atmospheric Environment Committee on Standards to jointly define "standards" for satellite drag models. As an initial step, the defining documents for selected versions of models used by the scientific and operational community are reviewed, and their inputs and outputs compared. Errors associated with the need to forecast solar inputs into empirical models are also examined. Forthcoming first-principles-based models that could sewe as future standards are also briefly described.

A 3-D staring radar operates by using a wide beam transmitter to illuminate the entire surveillance region and generates multiple receive beams using a 2-D static array that can be digitised at element level. The sensor achieves permanent search in all directions and harnesses the spatial, temporal and spectral domains to improve detection and discrimination of low observable, highly manoeuvrable targets in congested air space against strong non-stationary clutter. While the susceptibility of traditional scanning radars to jammers has been well researched, very little work has been carried out to assess the performance of 3-D staring radars in the presence of an interference source. In this paper, the response of a staring array radar to a jammer is modelled. Results are presented showing that by exploiting the persistent dwell time of the staring array, it is possible to achieve effective jammer suppression using null steering or similar techniques.