Using Laser Weapon To Shield Earth From Asteroid Impacts

Scientists propose the use of laser weapons to shield the Earth from asteroid impacts.

The possibility of asteroids impacting the Earth has kept some scientists busy with finding ways to avert such hazards. One such concept has recently been put in the spotlight: using a laser weapon to protect the planet from killer asteroids.

a) Concept diagram of an orbiting DE-STAR engaged in multiple tasks including asteroid diversion, composition analysis, and long-range spacecraft power and propulsion. (b) Visualization of a laser beam with relevant physical phenomenon included at a flux of about 10 MW/m2. Credit: Kosmo et al. Read more at: http://phys.org/news/2016-03-laser-weapon-earth-killer-asteroids.html#jCp
a) Diagram of an orbiting DE-STAR programmed to divert asteroids and carry out composition analysis, and long-range spacecraft power and propulsion. (b) A laser beam in action. Photo credits: Kosmo et al.

Shielding the Earth from threats of asteroid impacts with a huge phased-array laser in its orbit — this is what Project DE-STAR (Directed Energy System for Targeting of Asteroids and exploRation) is about. Asteroids, comets, and any other near-Earth objects (NEOs) that could endanger the planet would be deflected with the laser weapon. Another form of this technology is the DE-STARLITE that would cause a gradual deflection of the threat by travelling side by side with it.

The main goal of the researchers behind these proposals was to put together an orbital defense system whose purpose would be to vaporise the NEOs so that they are deviated from their original path: this would be done by heating their surface to cause ejection of vaporised material, thereby generating a reactionary force that would, in turn, send the object flying into another path.

The heating process would be done by a laser which would be projected towards a certain spot on a distant asteroid. We already have the technology required: current powerful lasers are able to melt and vaporise any known material. The challenge, on the other hand, lies in constructing a DE-STAR of the appropriate scale, as points out one of the authors of the project, Qicheng Zhang from the University of California, in a statement to Astrowatch.net.

The calculations made so far put this at a 330-feet-wide phased laser array. A DE-STAR equipped with an array of this size would be able to send away volatile-laden asteroids as large as 330 feet in diameter if engagement is initiated at around 2 million miles; lasers of greater size should be able to tackle big threats in less time. However, the more practical choice is DE-STARLITE which is smaller, not to mention cheaper. But, this has its own limitations. For instance, a tiny 20 kW DE-STARLITE will divert a 300-meter-wide NEO in 15 years, which makes it inadequate to take care of short-notice threats. This is why, despite the challenge, the DE-STAR system would be a better option for the distant future.

Both DE-STAR and DE-STARLITE are considered promising technology for systems pertaining to planetary defense.

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