DE-STAR

Directed Energy Planetary Defense

DE-STAR or Directed Energy System for Targeting of Asteroids and exploRation is a proposed system to deflect asteroids, comets, and other near-Earth objects (NEO) that pose a credible risk of impact. The objects that cross Earth’s orbit, even relatively small ones, can still have a devastating effect. We propose an orbital planetary defense system capable of heating the surface of potentially hazardous objects to the point of vaporization. DE-STAR is a modular phased array of kilowatt class lasers powered by photovoltaics.

We consider two classes of systems:

large “stand-off” DE-STAR arrays, which remain in Earth orbit and deflect the target from afar, and much smaller “stand-on” DE-STARLITE systems which travel to and deflect from alongside the target

The modular design allows for incremental development and test, lowering cost, minimizing risk, and allowing for technological co-development. While DE-STAR is designed as a stand-off system (able to accomplish a task from afar), DE-STARLITE is a much smaller version which is deployable on a single launcher but still capable of mitigating large asteroids given sufficient warning.

In both cases, highly-focused energy raises the temperature of a spot on the target’s surface to ~3000 K, allowing direct vaporization and ejection of surface material altering the asteroid’s or comet’s orbit. Ideal DE-STAR systems can simultaneously engage multiple targets.

Additional applications of these arrays include space debris mitigation, powering or recharging of distant probes, standoff power to remote facilities, standoff photon drive propulsion of small spacecraft that can achieve relativistic speeds (see DEEP-IN), composition analysis of remote objects including asteroids, and many others. The implications for SETI and ultra long range beacons extending even beyond our galaxy are also discussed.

PDC April 2015 Simulated Threat (click to expand) A hypothetical threat from a large asteroid was presented at the Planetary Defense Conference in Frascati, Italy in April 2015 (see PDC 2015 threat simulation details – PDF). Orbital simulation are done with a 3 body numerical solver and the results are compared to analytic approximations that are sometimes used (the 3 delta approximation). The numerical simulations are the proper way to look at a detailed mission while the analytic approximations are used for quick rough mission designs. 100m-2N.mvt 100m-12N.mvt 200m-12N.mvt 200m-50N.mvt 300m-50N.mvt 500m-50N.mvt 500m-100N.mvt 500m-500N.mvt Suppose we send a DE-STARLITE mission to an asteroid and it arrives at the asteroid 4 years before impact (when the asteroid is ~2.9 au from the Earth). How far will the asteroid be deflected? Here’s a comparison of a 100 m, 200 m and a 300 m diameter asteroid with a 12 N thrust (~ 100-200 kW laser). As can be seen even large asteroids can be effectively deflected even with modest DE-STARLITE missions. If we begin the interdiction process even earlier the laser power requirements are reduced or if larger power is used even short interdiction times are feasible. See our papers for more detailed mission discussions.

Miscellaneous Videos

Laboratory tests of high efficiency 19 element laser at 808 nm focused onto a Basalt target at a flux of about 20 MW/m2. Max spot temperature is mass ejection limited at about 2600-3000K. Physics based simulation of laser interaction with asteroid Apophis (325 m diameter) at 1 AU. Made by Caio Motta with Cinema 4D Studio donated by MAXON Computer. Plume ejecta speeds are approximately 1 km/s. Asteroid composition is typical high temperature rocky material (Si, Al, Fe, Mg oxides etc) with a spot temperature that is mass ejection limited at about 3000 K for this example compound.



We gratefully acknowledge support from the NASA California Space Grant Consortium.