Directed energy planetary defense

Kosmo, Kelly; Lubin, P. M.; Hughes, Gary B.; Griswold, Janelle; Zhang, Qicheng; Brashears, Travis

doi:10.1109/aero.2015.7119018

Cited by 9 publications

(14 citation statements)

References 27 publications

(26 reference statements)

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“…Model results indicate a solid theoretical foundation supporting the proposed method. 3,10,21,22,23 The model suggests that vaporization commences within 1 second; the thermal profile stabilizes at a level consistent with the vaporization temperature of Silica in vacuum. Temperatures within the illuminated spot rise to the point of being mass ejection limited, which is ~2 250 K in the center of the spot.…”

Section: Composition Of Solar System Objectsmentioning

confidence: 75%

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Stand-off molecular composition analysis

et al. 2015

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Composition of distant stars can be explored by observing absorption spectra. Stars produce nearly blackbody radiation that passes through the cloud of vaporized material surrounding the star. Characteristic absorption lines are discernible with a spectrometer, and atomic composition is investigated by comparing spectral observations with known material profiles. Most objects in the solar system-asteroids, comets, planets, moons-are too cold to be interrogated in this manner. Material clouds around cold objects consist primarily of volatiles, so bulk composition cannot be probed. Additionally, low volatile density does not produce discernible absorption lines in the faint signal generated by cold objects. We propose a system for probing the molecular composition of cold solar system targets from a distant vantage. The concept utilizes a directed energy beam to melt and vaporize a spot on a distant target, such as from a spacecraft orbiting the object. With sufficient flux (~10 MW/m 2) on a rocky asteroid, the spot temperature rises rapidly to ~2500 K, and evaporation of all materials on the surface occurs. The melted spot creates a high-temperature blackbody source, and ejected material creates a molecular plume in front of the spot. Bulk composition is investigated by using a spectrometer to view the heated spot through the ejected material. Spatial composition maps could be created by scanning the surface. Applying the beam to a single spot continuously produces a borehole, and shallow sub-surface composition profiling is possible. Initial simulations of absorption profiles with laser heating show great promise for molecular composition analysis.

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Section: Composition Of Solar System Objectsmentioning

confidence: 75%

“…Results from a multi-physics model of a spherical bolide of micro-crystalline Silica (SiO 2 ). 21,23 Model features include radiation, conduction and mass ejection. Left: Conceptual illustration of a directed energy beam impinging on an asteroid; surface material is ejected from the heated spot, creating a plume.…”

Section: Figurementioning

confidence: 99%

Stand-off molecular composition analysis

et al. 2015

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“…We will assume later that β =1 but it is important to keep this enhancement possibility in mind to be fair. The change of speed is thus: ΔV = β·mv/M = β·v (m/M) (8) The deflection distance at the Earth is approximately: Δx impactor = 3 ΔV·τ impact = 3· β·v·τ impact (m/M) (9) where the factor of 3 is the same approximation used from orbital dynamics but as we have shown in several of our papers it is not always a good approximation (Zhang et al, 2015-1, Zhang et al, 2015 We use it here for analytic purposes for simplicity and because it is often used in mission planetary defense planning exercises. We also note that for impactors there can be an additional effect do the mass ejection upon impact.…”

Section: Impactor Comparisonmentioning

confidence: 98%

“…Fluctuations in the Earth's atmosphere significantly hinder ground-based directed energy systems; thus, deploying a directed energy system above Earth's atmosphere eliminates such disturbances, as the interplanetary medium is not substantial enough to significantly affect the coherent beam. DE-STAR is discussed extensively in other papers Kosmo et al, 2015;Lubin et al, 2014). The broader DE-STAR system is not discussed in depth in this paper, which will focus on DE-STARLITE.…”

Section: De-star and De-starlitementioning

confidence: 99%

Directed energy missions for planetary defense

Lubin¹,

Hughes²,

Eskenazi³

et al. 2016

Advances in Space Research

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Directed energy for planetary defense is now a viable option and is superior in many ways to other proposed technologies, being able to defend the Earth against all known threats. This paper presents basic ideas behind a directed energy planetary defense system that utilizes laser ablation of an asteroid to impart a deflecting force on the target. A conceptual philosophy called DE-STAR, which stands for Directed Energy System for Targeting of Asteroids and exploration, is an orbiting stand-off system, which has been described in other papers. This paper describes a smaller, stand-on system known as DE-STARLITE as a reduced-scale version of DE-STAR. Both share the same basic heritage of a directed energy array that heats the surface of the target to the point of high surface vapor pressure that causes significant mass ejection thus forming an ejection plume of material from the target that acts as a rocket to deflect the object. This is generally classified as laser ablation. DE-STARLITE uses conventional propellant for launch to LEO and then ion engines to propel the spacecraft from LEO to the near-Earth asteroid (NEA). During laser ablation, the asteroid itself provides the propellant source material; thus a very modest spacecraft can deflect an asteroid much larger than would be possible with a system of similar mission mass using ion beam deflection (IBD) or a gravity tractor. DE-STARLITE is capable of deflecting an Apophis-class (325 m diameter) asteroid with a 1-to 15-year targeting time (laser on time) depending on the system design. The mission fits within the rough mission parameters of the Asteroid Redirect Mission (ARM) program in terms of mass and size. DE-STARLITE also has much greater capability for planetary defense than current proposals and is readily scalable to match the threat. It can deflect all known threats with sufficient warning.

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“…Smaller arrays would be useful for missions that deploy to an area near the asteroid, deemed DE-STARLITE. 3,4 An operational DE-STAR or DE-STARLITE would be capable of serving diverse scientific objectives, including spacecraft propulsion 5 , active illumination for asteroid search and orbit refinement 6 , stand-off composition analysis 7 , orbital debris removal and more; multiple uses of the DE-STAR system are depicted in Fig. 1.…”

Section: De-star System Conceptmentioning

confidence: 99%

Local phase control for a planar array of fiber laser amplifiers

Steffanic¹,

Johannes²,

Sison³

et al. 2015

SPIE Proceedings

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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 feedback. Most current control schemes sample individual emitter phases, such as with an array-wide beam splitter, and compare to a master phase reference. Reliance on a global beam splitter limits scalability to larger array sizes due to lack of design modularity. This paper describes a conceptual design and control scheme that relies only on feedback from the array structure itself. A modular and scalable geometry is based on individual hexagonal frames for each emitter; each frame cell consists of a conventional lens mounted in front of the fiber tip. A rigid phase tap structure physically connects two adjacent emitter frame cells. A target sensor is mounted on top of the phase tap, representing the local alignment datum. Optical sensors measure the relative position of the phase tap and target sensor. The tap senses the exit phase of both emitters relative to the target normal plane, providing information to the phase controller for each emitter. As elements are added to the array, relative local position data between adjacent phase taps allows accurate prediction of the relative global position of emitters across the array, providing additional constraints to the phase controllers. The approach is scalable for target distance and number of emitters without loss of control.

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Directed energy planetary defense

Cited by 9 publications

References 27 publications

Stand-off molecular composition analysis

Stand-off molecular composition analysis

Directed energy missions for planetary defense

Local phase control for a planar array of fiber laser amplifiers

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