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[1] Spectral domain forward modeling is used to generate topography-implied gravity for the Moon using data from the Lunar Orbiter Laser Altimeter instrument operated on board the Lunar Reconnaissance Orbiter mission. This is subtracted from Selenological and Engineering Explorer (SELENE)-derived gravity to generate band-limited Bouguer gravity maps of the Moon so as to enhance the gravitational signatures of anomalous mass densities nearer the surface. This procedure adds evidence that two previously postulated basins on the lunar farside, Fitzgerald-Jackson (25°N, 191°E) and to the east of Debye (50°N, 180°E), are indeed real. When applied over the entire lunar surface, band-limited Bouguer gravity reveals the locations of 280 candidate basins that have not been identified when using full-spectrum gravity or topography alone, showing the approach to be of utility. Of the 280 basins, 66 are classified as distinct from their band-limited Bouguer gravity and topographic signatures, making them worthy of further investigation.

High area-to-mass ratio (HAMR) inactive resident space objects (RSOs) in the geosynchronous orbit (GEO) regime pose a hazard to active GEO RSOs. The combination of solar radiation pressure (SRP), and solar and lunar gravitational perturbations causes perturbations in the orbits of these HAMR RSOs. The HAMR nature of these RSOs results in greater sensitivity to SRP forces resulting in the perturbation of mean motion, inclination and eccentricity. The subsequent drift with respect to the Earth, combined with time varying orientation with respect to the sun and transitions into and out of Earth's shadow, results in many of these RSOs being "lost" after initial acquisition as they transition through periods of days to weeks out of view of observing sites. This work examines the sensitivity of the prediction accuracies to inadequate modeling of the thermal emissions component of the SRP acceleration in the force models. The simplest models treat the thermal emission term either implicitly, or as a term that is a function of a fixed surface temperature and area. In reality, the temperature can vary with time for inert objects (e.g. orbital debris) transitioning in to and out of Earth shadow. Additionally, the orientation dynamics result in thermal acceleration components that vary relative to the inertial reference frame, and in general, have components orthogonal to the sun-object line. The prediction uncertainties associated with thermal modeling, orientation dynamics and materials uncertainties are examined in terms of the SRP acceleration perturbations for a range of representative HAMR object characteristics. Results indicate that significant prediction errors result from inadequate accounting for the thermal emissions component when compared to the standard SRP models used. These errors need to be addressed in the orbit determination and prediction to allow for more accurate re-acquisition and tracking, For presentation at the Adavance Maui Optical and Space Surveillance Technologies Conference (10th), 2009 AMOS, Maui, HI on 1-4 Sep 2009. Prepared in collaboration with the Directed Energy Directorate, Air Force Researh Laboratory, Kirtland AFB, NM.

In the past ten years the Moon has come fully back into focus, resulting in missions such as Clementine and Lunar Prospector. Data from these missions resulted in a boost in lunar gravity field modelling. Until this date, the lunar gravity field has mainly been expressed in a global representation, despite the lack of data over the far side of the Moon, which is the result of the spin-orbit resonance the Earth and Moon are in. To extract the wealth of information about the near side present in tracking data of the Lunar Prospector spacecraft, the global formulation is not efficient and regional representations become of interest. They can be used to derive accurate and high-resolution local gravity anomaly maps of the near side, which can help to understand the structure and evolution of the Moon, and consequently the Earth-Moon system, as they provide the boundary conditions for internal processes and structure. This dissertation presents a method for the regional recovery of gravity from satellite tracking data, in order to improve the resolution and accuracy of current lunar gravity field models and in order to exploit the high-resolution gravity information present in the data, without significant interference from the unknown far side. The recovery method has been applied to Lunar Prospector tracking data to create high-resolution solutions for parts on the near side of the Moon. The use of such a recovery method is not limited to one celestial body only and will be very valuable in planetary geodesy. Current and future dedicated gravity satellite missions should provide ample opportunity to apply a method as presented in this dissertation., Aerospace Engineering

In the past ten years the Moon has come fully back into focus, resulting in missions such as Clementine and Lunar Prospector. Data from these missions resulted in a boost in lunar gravity field modelling. Until this date, the lunar gravity field has mainly been expressed in a global representation, despite the lack of data over the far side of the Moon, which is the result of the spin-orbit resonance the Earth and Moon are in. To extract the wealth of information about the near side present in tracking data of the Lunar Prospector spacecraft, the global formulation is not efficient and regional representations become of interest. They can be used to derive accurate and high-resolution local gravity anomaly maps of the near side, which can help to understand the structure and evolution of the Moon, and consequently the Earth-Moon system, as they provide the boundary conditions for internal processes and structure. This dissertation presents a method for the regional recovery of gravity from satellite tracking data, in order to improve the resolution and accuracy of current lunar gravity field models and in order to exploit the high-resolution gravity information present in the data, without significant interference from the unknown far side. The recovery method has been applied to Lunar Prospector tracking data to create high-resolution solutions for parts on the near side of the Moon. The use of such a recovery method is not limited to one celestial body only and will be very valuable in planetary geodesy. Current and future dedicated gravity satellite missions should provide ample opportunity to apply a method as presented in this dissertation., Aerospace Engineering