NASA laser could vaporize asteroids that come too close

A high-power laser could deflect or vaporize the asteroid flying near Earth on March 5, 2016.

Philip LubinPhysics professor Philip Lubin from the University of California is leading  development on a NASA-funded phased-array laser system. He tells us what he envisions with this technology, and what asteroids like the March 8 flyby, are capable of.

ResearchGate: How does the laser work?

Philip Lubin: The solar-powered technology harnesses some of the sun’s power and converts it into electricity to power a large phased-array laser. These are directed at the potential threat – in this case an asteroid – and vaporizes it by heating a spot on its surface. The technology can also alter the asteroid’s trajectory, diverting it away from Earth by way of a reactionary thrust. It does this using the asteroid as the “fuel” for its own deflection.

RG: There are two versions of this technology – can you describe their differences?

PL: There’s a small and large version of the directed energy propulsion technology.

We call the large system DE-STAR, or Directed Energy System for Targeting of Asteroids and exploRation. This does not go directly to the asteroid, it is a “stand-off system” that stays in orbit around the earth (or nearby). It targets the asteroid at a distance and deflects it from afar.

DE-STARLITE is a more economical version of the larger system. It fits on a single launcher, goes out to the asteroid, and slowly deflects it overtime. It can do this for all known threats of any size but needs sufficient warning.


RG: How common are asteroids and what kind of damage are we talking?

PL: The number of times you get hit by a large asteroid are relatively small, although they can obviously be quite damaging. In the last 100-odd years we had one in Tunguska (1908), one in Chelyabinsk (2013), another one that came close that same day, and then also many close misses.

The problem is that even a relatively modest-sized asteroid can cause extensive damage. The Chelyabinsk asteroid was only about 20 meters in diameter, with half a megaton yield. That carries the equivalent energy of a midsize thermonuclear weapon. If it had hit a city it would have caused millions of casualties. If the other asteroid that flew past that day had actually hit us, then it probably would have had an impact energy of a 10 megaton event. The 1908 asteroid in Tunguska burst in mid-air and didn’t strike Earth’s surface. That was thought to have been around 50 to 100 meters in diameter, and have an estimated yield of 15 megatons. If that had hit a large city there’d have been enormous casualty rates.

RG: How do you detect asteroids?

PL: The most common method is looking at the sunlight reflected off them. When taking pictures of the sky we can see things that appear to be abnormal; things that are moving rapidly and different from a star or anything we know about. The problem with small asteroids is that they may just be too small or too fast that it was hard to track. That was the case in Chelyabinsk, Russia. You may recall that in February, 2013, we knew an asteroid was coming very close to Earth, but we didn’t know another asteroid was coming on the same day and would actually hit us. That was the surprising one. We have some sensing systems in place but they’re not good enough to prevent something like that.


Listen to Philip Lubin explain how this technology could be used for interstellar exploration. 

RG: What happens if there’s not sufficient warning?

PL: There’s nothing we could do if we found out a large asteroid was going to hit a month from now. Unless you know it’s coming at you then you can’t defend yourself. There’s no system in place, no deterrence threat ready. We have nothing. Detection is one of the absolute key aspects in planetary defense, and we haven’t built anything or planned anything that is sufficient. We’re simply hoping that whatever threat we find will be long enough into the future for us to plan, build, launch, and mitigate. That’s not an intelligent way to deal with threats.

RG: How and why is this the case?

PL: This is where the public comes into play. People need to rise up and say “enough, let’s do something about this.” We’re capable technologically of doing something, but there’s no mandate to do it. The problem is it’s nobody’s problem: It’s not the European Space Agency’s problem, it’s not NASA’s problem…Nobody has been directed by their government to build what it takes to at least detect them to a small enough size that is sufficient, let alone mitigate them.

I’m not saying this to make people anxious or nervous, but education is key. People need to understand the problem and the threat level. If you feel passionate about it then try to gauge the political apparatus in your country, and raise awareness.

RG: What else could the technology be used for?

PL: This same technology can be used to accomplish a number of tasks, even simultaneously. It can be used to deflect an asteroid or comet, launch a spacecraft to an exoplanet, and send power across vast distances – like to distant spacecraft or possibly outposts in the solar system. There may be ways we could begin to take more control of our own planet, possibly by modifying detrimental atmospheric phenomenon, for example. Or we could take more control of our own solar system, such as mitigating the threat of asteroids, rather than just being subject to the whims of nature.

Feature image courtesy of Q. Zhang