Gary B. Hughes

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We present an approach for finding the overlap area between two ellipses that does not rely on proxy curves. The Gauss-Green formula is used to determine a segment area between two points on an ellipse. Overlap between two ellipses is calculated by combining the areas of appropriate segments and polygons in each ellipse. For four of the ten possible(More)
Asteroids and comets that cross Earth’s orbit pose a credible risk of impact, with potentially severe disturbances to Earth and society. We propose an orbital planetary defense system capable of heating the surface of potentially hazardous objects to the vaporization point as a feasible approach to impact risk mitigation. We call the system DE-STAR, for(More)
We propose a directed energy orbital planetary defense system capable of heating the surface of potentially hazardous objects to the evaporation point as a futuristic but feasible approach to impact risk mitigation. The system is based on recent advances in high efficiency photonic systems. The system could also be used for propulsion of kinetic or nuclear(More)
We present results of optical simulations for a laser phased array directed energy system. The laser array consists of individual optical elements in a square or hexagonal array. In a multi-element array, the far-field beam pattern depends on both mechanical pointing stability and on phase relationships between individual elements. The simulation(More)
Directed Energy (DE) systems offer the potential for true planetary defense from small to km class threats. Directed energy has evolved dramatically recently and is on an extremely rapid ascent technologically. It is now feasible to consider DE systems for threats from asteroids and comets. DE-STAR (Directed Energy System for Targeting of Asteroids and(More)
On 15 February 2013, a previously unknown ~20 m asteroid struck Earth near Chelyabinsk, Russia, releasing kinetic energy equivalent to ~570 kt TNT. Detecting objects like the Chelyabinsk impactor that are orbiting near Earth is a difficult task, in part because such objects spend much of their own orbits in the direction of the Sun when viewed from Earth.(More)
Current strategies for diverting threatening asteroids require dedicated operations for every object. We propose a stand­ off, Earth-orbiting system capable of vaporizing the surface of asteroids as a futuristic but feasible approach to impact risk mitigation. We call the system DE-STAR (Directed Energy System for Targeting of Asteroids and exploRation).(More)
Directed energy in the form of photons plays an increasingly important role in everyday life, in areas ranging from communications to industrial machining. Recent advances in laser photonics now allow very large-scale modular and scalable systems that are suitable for planetary defense. The fundamental requirements of directed energy planetary defense(More)
  • Patrick Steffanic, Benjamin T. Johannes, +13 authors CA
  • 2015
Arrays of phase-locked lasers have been developed for numerous directed-energy applications. Phased-array designs are capable of producing higher beam intensity than similar sized multi-beam emitters, and also allow beam steering and beam profile manipulation. In phased-array designs, individual emitter phases must be controllable, based on suitable(More)
The sensor element of an imaging system should be mounted into its housing in such a way that the scene can be prop­ erly focused onto the sensor element’s focal plane over the active area. Operational imaging requirements are forcing increasingly smaller tolerances on sensor alignment, and manufacturing systems must improve alignment capability to keep(More)