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Scientists Envisage Using Lasers to Destroy Killer Asteroids

Asteroid Laser

In a way, this idea is not completely new. The comic books and sci-fi writers have given us a treat of this possibility; dare say in a more entertaining way than scientists may hope to.

However, scientists engaged in planetary defense issues have come up with several strategies to eliminate threats posed by potentially hazardous asteroids.

Although the primary targets of these methods are asteroids, scientists prefer to use the blanket term near-Earth objects (NEOs), as it includes other entities like comets that we may also want to get rid of because they enter Earth’s neighborhood dangerously.

Gaining wide acclaim within the scientific community are methods like robotic mining, gravity tractors, and kinetic impactors. Joining the ranks and probably scoring some points as one of the most serious proposal is the twin laser-based projects proposed by a team of researchers led by Qicheng Zhang of the University of California, Santa Barbara.

The twin projects are named Directed Energy System for Targeting of Asteroids and exploRation (DE-STAR) and DE-STARLITE. The idea behind both projects is to create a sort of defense system that could use laser to heat the surface of a potentially hazardous object to the point of vaporization.

The vaporization on the surface of the object will lead to ejection of vaporized material. Obeying simple laws of physics, this will create a reactionary force that pushes the object into a new path—effectively changing the course of the object.

DE-STARLITE

Stand-on DE-STARLITE single launcher based system for planetary defense.

Both projects, DE-STAR and DE-STARLITE, achieve this purpose; although they do so in a different way. DE-STAR involves placing a large phased-array laser in Earth orbit (similar to numerous satellites currently orbiting Earth) to create a kind of orbital planetary defense system. The system then focuses its heat at an NEO that may be as far out as 2 million miles.

DE-STARLITE takes a ‘more direct’ approach, so to speak. It involves sending a similar system to approach the target, the system then travels along with the target while deflecting the target slowly from close-by over a long period.

Choosing which system to use depends on a range of factors. One is the size of the laser. Another is the size of the NEO. Yet another is the amount of time needed to deflect the NEO.

The DE-STARLITE is much smaller and less expensive than the DE-STAR and is the more practical option if there is enough time to spare. This increased time requirement covers the extended time it takes the system to travel to the asteroid.

de-star

(a) Concept diagram of an orbiting DE-STAR engaged in multiple tasks including asteroid composition analysis, diversion and long-range spacecraft power and propulsion. (b) Visualization of a laser beam at a flux of about 10 MW/m2. (Image Credit: Kosmo)

Therefore, if there is not enough time, say in a situation where identification of the threat happens on short notice, then it pays to have a last line of defense—DE-STAR.

An orbiting DE-STAR of adequate size can rapidly respond to identified threats, small to moderate in size, when we have limited time to react. It could also stand in as a defense system against long-period comets, as it is currently not possible to reach them with a spacecraft.

The team notes that the unique characteristics of the NEO strongly affect the effectiveness of a deflection mission. Regardless, Zhang emphasizes that generally speaking, the technology to make these systems happen are mostly already available today. Thus, the methods based on laser ablation are now more practical than ever.

Zhang published his latest advanced in a study“Orbital Simulations on Deflecting Near-Earth Objects by Directed Energy”.

About the author

Dean Smith