The paper proposes a new passive bistatic ISAR mode for coastal surveillance based on the exploitation of the signals transmitted by telecommunication geostationary satellites. Specifically it is demonstrated that ISAR images with acceptable quality of ship targets could be obtained by using telecommunication geostationary satellites as opportunity transmitters and stationary passive devices, l...

We present a distributed control strategy that lets a swarm of satellites autonomously form a lattice in orbit around a planet. The system, based on the artificial potential field approach, proposes a novel way to split the artificial field in two main terms: a global artificial field that gathers the satellites around a predefined meeting point, and a local term that allows a satellite to plac...

We investigate the orbital resonant history of Proteus and Larissa, the two largest inner Neptunian satellites discovered by Voyager 2. Due to tidal migration, these two satellites probably passed through their 2:1 mean-motion resonance a few hundred million years ago. We investigate this resonance passage as a method to excite orbital eccentricities and inclinations, and find interesting const...

In this paper, we address the problem of managing the new generation of agile Earth Observing Satellites. Whereas non-agile satellites such as Spot have only one degree of freedom for acquiring images, the new generation satellites have three, giving opportunities for a more efficient scheduling of observations. A counterpart of this advantage is that the scheduling of observations is made much...

This paper investigates the design of the relative motion orbits of geostationary satellites in the presence of geometric constraints. A geometric constraint is defined by a sensor’s pointing direction and field of view. An analyis was made of the underlying geometry of the relative orbits associated to geometric constraints. This resulted in the derivation of novel relations between relative o...

[1] Large impact basins are present on many of the icy satellites of the outer solar system. Assuming that their present-day topography is uncompensated, such basins can cause significant poleward reorientations for slow-rotating satellites. This reorientation may have been accompanied by transient large-amplitude wobble. The largest basins on Tethys, Rhea and Titania are predicted to have caus...

We combine a series of high-resolution simulations with semi-analytic galaxy formation models to follow the evolution of a system resembling the Milky Way and its satellites. The semianalytic model is based on that developed for the Millennium Simulation, and successfully reproduces the properties of galaxies on large scales, as well as those of the Milky Way. In this model, we are able to repr...

Gravitational lenses with anomalous flux ratios are often cited as possible evidence for dark matter satellites predicted by simulations of hierarchical merging in cold dark matter cosmogonies. We show that the fraction of quads with anomalous flux ratios depends primarily on the total mass and spatial extent of the satellites, and the characteristic lengthscale d1/2 of their distribution. If d...

Haumea is a dwarf planet with two known satellites, an unusually high spin rate, and a large collisional family, making it one of the most interesting objects in the outer solar system. A fully self-consistent formation scenario responsible for the satellite and family formation is still elusive, but some processes predict the initial formation of many small moons, similar to the small moons re...

There is an increasing desire in many organizations, including NASA and the DoD, to use constellations or fleets of autonomous spacecraft working together to accomplish complex mission objectives. At the Air Force Research Laboratory’s (AFRL) Space Vehicles Directorate we are investigating and developing architectures for commanding and controlling a cluster of cooperating satellites. For many ...