This tutorial paper describes the current development in the use of low earth orbiting satellites (LEOS) for global personal communications. The basic architectures and rationales for design choices are discussed. Representative TDMA and CDMA systems are outlined and a summary of the diierences between LEOS communications and terrestrial cellular is presented along with the prospects for CDMA b...

We calculate analytically the most relevant nongravitational perturbations on the mean anomaly of LAGEOS type satellites in order to investigate the constraints they pose on the feasibility of the proposed general relativistic gravitomagnetic clock effect. The gravitoelectric contributions to the proper times induced by the perturbations on the Keplerian mean motions of two counter-orbiting sat...

0-7803-7651-X/03/$17.00 © 2003 IEEE IEEEAC paper #1159, Updated December 19, 2002 Abstract⎯The paradigm shift in the late 1980’s from large satellites to small satellites required that new methodologies be developed to assess their cost. In 1991, The Aerospace Corporation (Aerospace) began to study small satellites to better understand the design principles that were being employed in their imp...

We find that satellites of isolated disk galaxies at projected radii between 300 and 500 kpc are distributed asymmetrically about the parent galaxy and aligned preferentially with the disk minor axis. The dynamical timescale at these radii is sufficiently long that the shape of this distribution must reflect the formation history of the outer halo rather than its internal evolution. We also fin...

Tectonic features on the satellites of the outer planets range from the familiar, such as clearly recognizable graben on many satellites, to the bizarre, such as the ubiquitous double ridges on Europa, the twisting sets of ridges on Triton, or the isolated giant mountains rising from Io’s surface. All of the large and middle-sized outer planet satellites except Io are dominated by water ice nea...

Cartographic and topographic mapping of the major satellites of the Outer Solar System has been in progress since the late 1980’s, beginning with Voyager image data, and incorporating Galileo and recently Cassini imaging data as released to the public. Global image mosaics, based on cartographic control nets, have been produced for all these satellites. In addition, digital topographic maps hav...

NASA has been interested in having Internet connectivity in space for quite some time. This would allow scientists with direct Internet access to data and devices on the satellites. The rotation of Low Earth Orbiting (LEO) satellites around the Earth result in handover of satellites between ground stations. Two types of handover can be observed in space: Link layer and Network layer. Researcher...

The spatial distribution of the Galactic satellite system plays an important role in Galactic dynamics and cosmology, where its successful reproduction is a key test of simulations of galaxy halo formation. Here, we examine its representative nature by conducting an analysis of the 3-dimensional spatial distribution of the M31 subgroup of galaxies, the next closest system to our own. We begin b...