Search

This paper continues the development of a concept for a low-earth-orbit-based optic-fiber-communication system that may ameliorate some limitations of present space communications systems. Starting with an assumption that a circum-terra ring can be deployed in LEO, a high-bandwidth, optical-fiber-based, communication system has been proposed as the first of a system of LEO and higher-orbit (MEO) rings for different purposes. These rings about the Earth would complement existing terrestrial and space communications networks and thereby improve global connectivity and throughput. In particular, networking issues necessary for both initial and expanded-ring system communications are addressed.

Platform: What physical attributes separate EM waves, of the enormous band of radio to visible to x-ray, from the high energy narrow band of gamma-ray? From radio to visible to x-ray, telescopes are designed based upon the optical imaging theory; which is an extension of the Huygens-Fresnel diffraction integral. Do we understand the physical properties of gamma rays that defy us to manipulate them similarly? One demonstrated unique property of gamma rays is that they can be converted to elementary particles (electron and positron pair); or a particle-antiparticle pair can be converted into gamma rays. Thus, EM waves and elementary particles, being inter-convertible; we cannot expect to understand the deeper nature of light without succeeding to find structural inter-relationship between photons and particles. This topic is directly relevant to develop a deeper understanding of the nature of light; which will, in turn, help our engineers to invent better optical instruments.

The development of a Low-Earth-Orbit (LEO) based solar-shade system, as part of a technically- and financially-viable multipurpose system to provide long-term solutions to global warming and the energy crisis is discussed. The proposed solar-shade and power system would be enabled by the development of a previously-proposed less-expensive, environment-friendly, space-elevator system to lift mass into space. The solar shades, even during their early deployment and growth in LEO, would provide benefits such as reduction of space-debris and depletion of the Van Allen radiation belts.The Terrestrial temperature profile has been approximated for each latitudinal zone with a one-dimensional model. A shade ring at an altitude of 2000-4000 km, consisting of thin-film mega panels totaling up to 4% of the earths surface area (to block ~1% of insolation), is proposed. The effects of such near-polar rings on the global temperature pattern has been examined using the simple model. Specific emphasis has been laid on this effect in the Polar Regions. One such proposed ring could reduce the peak summer temperature of the Polar Regions (80-90 degree latitude) by almost 3K. The tilting of the solar-shades, to reduce their cooling effect at the poles and to increase it in the near-polar regions, is recommended., Comment: 11 pages, 6 figures Proc. of Int. Astronautics Congress, IAC-2009, Daejeon, Korea, Oct. 2009

Comparing to the traditional communication mechanism overlay networks offer an enhanced alternative for content delivery in terms of flexibility, scalability, and ease of deployment. In order to maximize the benefits of overlay networks flexible and scalable methods for content transmission and content representation are needed. This paper proposes a new content distribution model with overlay path probing mechanism for fast and efficient data dissemination in P2P overlay networks with heterogeneous overlay nodes. The proposed overlay path probing is an in-band approach whereby the actual content, sent over TCP, is exploited for probing purpose instead of injecting extra dummy packets into the native network. The proposed mechanism is capable of providing accurate and up-to-date estimation of the end-to-end capacity and the available bandwidth of overlay paths continuously. Therefore, the content distribution model will be able to dynamically adjust the transmission rate of the content to downstream links according to the available bandwidth along each overlay path to achieve better resource utilization. Several P2P applications such as P2P file sharing and CDNs can benefit from the enhanced content distribution model which can support simultaneous parallel downloads from multiple sources with multiple rates.

Dowling and Gea-Benacloche (1992) proved mathematically that "...under certain circumstances, it is possible to consistently interpret interference as the specular reflection of two electromagnetic waves off each other..." Combining experiment, model, and logic, we confirm this statement. Contrary to the supposition that electromagnetic waves/photons cannot interact, it is possible to interpret the results to indicate that identical out-of-phase waves and opposite polarity photons repel or, at least, cannot pass through each other. No energy is detected in the dark/null zones of wave interference. Because energy appears to be absent, the exchange of momentum through the null zone must redirect/repel light waves into bright zones. Our Zero-Slit Experiment (ZSX) provides diffraction-free interference in air between two portions of a divided laser beam. This experiment was initially an attempt to completely cancel a section of these two beams by recombining them in air when they are 180° out-of-phase. We have reduced interference patterns close to a double-bright zone (with 3 null zones), but no further. Within the limits of laser-beam spreading, we have studied the resulting interference patterns and compared them with models of collision between identical particles. It may be possible to distinguish light from other Bosons, if the model of opposite phases repelling is valid. An EM field-line model of the photon is presented to explain the interactions needed to produce momentum transfer.

Maxwell did not believe in photons. However, his equations lead to electro-magnetic field structures that are considered to be photonic by Quantum ElectroDynamics (QED). They are complete, relativistically correct, and unchallenged after nearly 150 years. However, even though his far-field solution has been considered as the basis for photons, as they stand and are interpreted, they are better fitted to the concept of virtual rather than to real photons. Comparison between staticcharge fields, near-field coupling, and photonic radiation will be made and the distinctions identified. The question of similarities in, and differences between, the two will be addressed. Implied assumptions in Feynman's "Lectures" could lead one to believe that he had provided a general classical electrodynamics proof that an orbital electron must radiate. While his derivation is correct, two of the conditions defined do not always apply in this case. As a result, the potential for misinterpretation of his proof (as he himself did earlier) for this particular case has some interesting implications. He did not make the distinction between radiation from a bound electron driven by an external alternating field and one falling in a nuclear potential. Similar failures lead to misinterpreting the differences between virtual and real photons.

We seek physical mechanisms underlying a model of the interaction of light with light (and with matter) by examining the process of photon creation. A model of the atomic orbitals and optical transitions is described considering a classical argument that does not presume the integer values of electron-orbital angular momentum proposed by Bohr. Assuming only the known properties of light (e.g., E γ = h ν and L γ = h/2 π ), the electron-orbital energies about a nucleus (including a ground state) are predicted and calculated in an intuitive (and mathematically simple) manner. This first-order model considers neither electron-spin nor relativistic effects. A ground state is predicted based on the reduced probability of coupling net energy from a driver into a lower-frequency oscillator. The long-term stability of the ground state is further explained in terms of angular-momentum requirements of the photon. A simple derivation for the radius and angular momentum of photons is provided. It is proposed that, when a collinearly-propagating photon density gets high enough, their fusion back into electromagnetic fields (spherical or plane wave) is a similar process to their formation, but in reverse. The similarities and differences will be described assuming a surface-tension-like mechanism necessary for the existence of photons.

A multi-purpose low-earth-orbit system of rings circling the earth - the "LEO ARCHIPELAGO" - is proposed as a means of solving or bypassing many major problems hindering man's quest to get into space. A fiber-optic ring about the earth would be an initial testing and developmental stage for the ring systems, while providing cash-flow through a LEO-based, high-band-width, world-wide communication system. A Low-Earth-Orbit-based space-elevator system, "Sling-on-a-Ring," is proposed as the crucial developmental stage of the LEO Archipelago. Being a LEO-based heavy-mass lifter, rather than earth- or GEO-based, it is much less massive and therefore less costly than other proposed space-elevators. With the advent of lower-cost, higher-mass transport to orbit, the options for further space development (e.g., communications, space solar power, radiation dampers, sun shades, and permanent LEO habitation) are greatly expanded. This paper provides an update of the Sling-on-a-Ring concept in terms of new materials, potential applications, and trade-offs associated with an earlier model. The impact of Colossal Carbon Tubes, CCT, a material with high tensile strength, extremely-low density, and other favorable properties and new technologies (e.g., solar-powered lasers, power beaming to near-space and earth, and thermal-control systems) on the development of associated LEO-Ring systems (e.g., "Solar-Shade Rings" and "Power Rings") is also explored. The material's effect on the timeline for the system development indicates the feasibility of near-term implementation of the system (possibly within the decade). The Sling-on-a-Ring can provide a less-expensive, environment-friendly, mode of access to space. This would pave the way (via eventual operation at >1000 tonnes per day by 2050) for large scale development of space-based technologies., 22 pages, 7 figures, Revised version (responding to reviewers comments). Final version to be published in Acta Astronautica

We propose a LEO-based communication system that is built by deploying circum-terra, optic fibers connecting hundreds of small (perhaps) phased-array-communications and RF-signal-transfer antennas around the earth on multiple rings. The proposed LEO-earth connection will be through microwave links (Ku or low-Ka band) and many of the ISL's through the optic-fiber rings. Inter-ring connectivity could be with either high-Ka band or optical (laser) links. The initial ring would serve to complement existing terrestrial fiber networks; but, the system would expand with additional rings into non-equatorial planes to provide global connectivity. The proposed system would make use of connectivity & broadcasting capability of satellite constellations as well as the high throughput point-to-point capability of optic-fiber systems. The advantages, options, and economics of the proposed LEO optic-fiber / microwave communication system over existing terrestrial- and space-communication systems (of similar functionality) as well as the future development of the system are dealt with in the paper., 12 pages, 3 appendices. Presented at the 59th International Astronautical Congress, Glasgow, Scotland, (2008). IAC-08-B2.5.2

It is concluded from a thermochemical analysis that the steady-state “excess heating” observed in calorimetric experiments1 is attributable to the heat of formation of liquid D2O resulting from recombination of D2 and O2 gases generated in the electrolytic cell. The recombination is catalyzed by both electrodes and the extent of the reaction increases on stirring, especially when D2 gas sparging is used for this purpose. Thermal effects of stored chemical energy, which include thermal power output exceeding electrical input in the short term and cathode meltdown from total sudden release, arise from storage of D atoms in supersaturated solid solution within the cathode volume. Their recombination to form D2 builds up high internal pressures, causing multiple fracture. Excess heat is liberated as D atoms and D2 molecules fall into deep traps created on fresh Pd surfaces, supplemented by D recombination heat. Postulation of unknown nuclear processes to account for the heat is not necessary.

Silicon operating in a vacuum is a good candidate thermal emitter since it has a high melting point (1680 K). The semiconductor bandgap, which can provide selective emission, adds to the potential for high operating temperature and, therefore, high radiated power. We present the detailed emitter theory, along with both theoretical and experimental results for spectral emittance of thin (∼1 μm) silicon films on sapphire substrates with a platinum backing. These results show the importance of temperature and film thickness in determining the selective spectral emittance and, with the proper material parameters, can be readily extended to other materials and systems.

This paper presents an overview of the near-earth, space-radiation environment, its effects on space craft that must exist in it, and means of quantifying and reducing these effects. Other aspects of the space environment are touched on for completeness and because they can impact both the consequences of radiation damage and the damage itself. Of necessity, the overview of such a large field in a small space must be cryptic. The goal is to familiarize at least a small portion of the opto-electronics community with the space and spacecraft-manufacturing environment in which they will be contributing their technology to an ever-increasing extent.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The ability to acquire, track, and accurately direct a laser beam to a satellite is crucial for power-beaming and laser-communications. To assess the state of the art in this area, a team consisting of Air Force Phillips Laboratory, Sandia National Laboratories, and COMSAT Corporation personnel performed some laser beaming demonstrations to various satellites. A ruby laser and a frequency-doubled YAG laser were used with the Phillips Lab Starfire Optical Range (SOR) beam director for this activity. The ruby laser projected 20 J in 6 ms out the telescope with a beam divergence that increased from 1.4 to 4 times the diffraction limit during that time. The doubled YAG projected 0.09 J in 10 ns at 20 Hz. The SOR team demonstrated the ability to move rapidly to a satellite, center it in the telescope, then lock onto it with the tracker, and establish illumination. Several low-earth-orbit satellites with corner-cube retro-reflectors were illuminated at ranges from 1000 to 6000 km with a beam divergence estimated to be about 20 {mu}radians. The return signal from the ruby laser was collected in a 15-cm telescope, detected by a photomultiplier tube, and recorded at 400 kHz. Rapid variations in intensity (as short at 15 {mu}s) were noted, which may be due to speckles caused by phase interference from light reflected from different retro-reflectors on the satellite. The return light from the YAG was collected by a 35-cm telescope and detected by an intensified CCD camera. The satellite brightened by about a factor of 30 in the sunlight when the laser was turned on, and dimmed back to normal when the 50-{mu}radian point-ahead was turned off. The satellite was illuminated at 1 Hz as it entered the earth`s shadow and followed for about 10 seconds in the shadow. In another demonstration, four neighboring GEO satellites were located and centered in succession with a 3.5-m telescope at a rate of about 16 seconds per satellite.

A team of Phillips Laboratory, COMSAT Laboratories, and Sandia National Laboratories plans to demonstrate state-of-the-art laser-beaming demonstrations to high-orbit satellites. The demonstrations will utilize the 1.5-m diameter telescope with adaptive optics at the AFPL Starfire Optical Range (SOR) and a ruby laser provided by the Air Force and Sandia (1 - 50 kW and 6 ms at 694.3 nm). The first targets will be corner-cube retro-reflectors left on the moon by the Apollo 11, 14, and 15 landings. We attempt to use adaptive optics for atmospheric compensation to demonstrate accurate and reliable beam projection with a series of shots over a span of time and shot angle. We utilize the return signal from the retro- reflectors to help determine the beam diameter on the moon and the variations in pointing accuracy caused by atmospheric tilt. This is especially challenging because the retro-reflectors need to be in the lunar shadow to allow detection over background light. If the results from this experiment are encouraging, we will at a later date direct the beam at a COMSAT satellite in geosynchronous orbit as it goes into the shadow of the earth. We utilize an onboard monitor to measure the current generated in the solar panels on the satellite while the beam is present. A threshold irradiance of about 4 W/m2 on orbit is needed for this demonstration.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Radiation damage to high-electron-mobility transistor (HEMT) structures, and its effect on electrical characteristics, are discussed. Radiation from cobalt 60 gamma and nuclear reactor sources was used on microwave and millimeter-wave monolithic circuits to determine total dose sensitivity. Heavy ions (15-MeV silicon) were used to evaluate other potential damage mechanisms. The dc and RF results for a 60-GHz-band monolithic microwave integrated circuit (MMIC) before and after irradiation are presented. The HEMT structures were found to be as resistant to radiation as previously tested metal-semiconductor field-effect transistors (MESFETs), and no new damage mechanisms were observed.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Models to account for the observed experimental results for low-energy nuclear reactions in palladium– deuteride systems are presented along with calculated results. The crucial idea is a mechanism of improved probability for the needed penetration of the Coulomb barrier for a D–D reaction. This facilitation occurs, in general, with the formation of $D^-$ ions at special frequency modes (e.g. via phonons) and, specifically for the laser-stimulated case, with utilization of enhanced optical potential at a selected interface. Both mechanisms may work individually, or together, to increase the probability of barrier penetration.