Directed Energy for Planetary Defense and Relativistic Probes – DE-STAR

Asteroids and comets that cross Earth’s orbit pose a credible risk of impact, with potentially severe disturbances to Earth and society. Numerous risk mitigation strategies have been described, most involving dedicated missions to a threatening object. 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 Directed Energy System for Targeting of Asteroids and exploRation. DE-STAR is a modular phased array of kilowatt class lasers powered by photovoltaic’s. Modular design allows for incremental development, test, and initial deployment, lowering cost, minimizing risk, and allowing for technological co-development, leading eventually to an orbiting structure that would be developed in stages with both technological and target milestones.

The main objective of DE-STAR is to use the focused directed energy to raise the surface spot temperature to ~3,000 K, allowing direct vaporization of all known substances. In the process of heating the surface ejecting evaporated material a large reaction force would alter the asteroid’s orbit. The baseline system is a DE-STAR 3 or 4 (1-10 km array) depending on the degree of protection desired. A DE-STAR 4 allows for asteroid engagement starting beyond 1 AU with a spot temperature sufficient to completely evaporate up to 500 m diameter asteroids in one year and can deflect multi km diameter asteroids if needed.  Small asteroids and comets can be diverted/evaporated with a DE-STAR 2 (100m) while space debris is vaporized with a DE-STAR 1 (10 m). The system is inherently modular and is assembled from a number of identical sub assemblies, allowing for mass production, each of which is small enough to fit into a launch shroud.

The system is inherently multi-tasking and can simultaneous engage multiple target or missions. Additional mission tasks include powering or recharging of very distant probes, standoff power to remote facilities, standoff photon drive propulsion of small spacecraft that can achieve mildly relativistic speeds, laser powered conventional (thermal) propulsion (no oxidizer needed), laser powered ion dive, standoff composition analysis of remote objects including asteroids, active illumination detection of asteroids (LIDAR), space debris removal, SPS mode for sending excess powered to the ground or airborne systems  via micro or millimeter waves as well as laser,  satellite orbital boosting (LEO to GEO for example), extremely long range high speed IR communications to spacecraft and exoplanets and standoff terraforming possibilities among many others.

Smaller versions of the same system design can be used for “stand-on” applications for orbital diversion by taking the laser system to the target asteroid in a dedicated mission as well as for close in composition analysis etc. An example of a “stand-on” version is DE-STARLITE that is discussed in Kosmo et al 2014 among our other papers.

Hypervelocity Impact Symposium – HVIS – Boulder, CO  April 2015

Zhang-HVIS_v11

Planetary Defense Conference – PDC – Frascati, Italy   April 2015

Brashears etal PDC2015 Poster Directed Energy Laboratory Measurements_V10

Brashears etal PDC2015 Directed Energy Deflection Laboratory Measurements v22

Lubin etal PDC2015 Effective Planetary Defense using Directed Energy

 

Vacuum chamber laser targeting of “asteroid like” sample at flux level >10 MW/m^2

See Brashears et al PDC 2015 above for details.

PDC April 2015 Simulated Threat

PDC 2015 threat simulation information

Below is a response to a hypothetical threat from a large asteroid as presented at the Planetary Defense Conference in Frascati, Italy in April 2015. The 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 misision designs. See our papers for more details.

 

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 12N 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.


SPIE Photonics August 2014

Kosmo_etal_DE-STARLITE-16

JohanssonHummelgard_etal_SPIE2014_AsteroidRotation_PaperV36gbh

Riley_etal_SPIE2014_Active_Illumination_Manuscript_R00-10

Hughes_etal_SPIE2014_OpticalSimulation_Paper_R05

Optical Engineering article – Toward Directed Energy Planetary Defense – Lubin et al, March 2014:

SPIE Optical Engineering – Towards Directed Energy Planetary Defense – Lubin at al 2014

 

SPIE Photonics  August2013 invited talks conference proceedings:

Planteary Defense – SPIE Aug 2013 – Lubin – 8876-101-final

Hughes_etal_2013_DE_STAR_PlanetaryDefense-final

 

SPIE Photonics August 2013 student conference proceeding on directed energy standoff propulsion for relativistic probes:

Bible-8876-38 – as published

 

SPIE Photonics August 2013 video of invited plenary talk and related information:

http://spie.org/app/program/index.cfm?fuseaction=secategorydetail&catid=298&event_id=896200&export_id=x30628&ID=x34417&redir=x34417.xml

http://spie.org/x102952.xml

http://optics.org/news/4/8/30

http://spie.org/x104781.xml

 

Big Science Radio Interview – Planetary Defense and SETI – February 2014
http://radio.seti.org/blog/2014/03/big-picture-science-space-for-everyone-philip-lubin/

http://bit.ly/1hYyM4g

 

SETI Talk – Directed Energy for Planetary Defense and Implication for Searches for Advanced Civilizations – February 2014:

SETI Talk – Directed Energy for Planetary Defense and Implication for Searches for Advanced Civilizations – February 2014

 

 

Laboratory tests of high efficiency 19 element laser at 808 nm focused onto a Basalt target at a flux of about 20 MW/m^2. 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. Click on image to start and stop video. 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 3000K for this example compound.

 

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