Podcast: Interstellar exploration is possible within our lifetime

Laser-powered spacecrafts could get to the closest stars in less than 50 years.

NASA just released a sneak peek of DEEP-IN: a project that uses new directed energy propulsion technologies for interstellar exploration. Listen as head researcher, physicist Philip Lubin (University of California), breaks down this radically new system, and explains how it could be capable of more than several hundred interstellar missions a day.


Check out our interview with Philip Lubin about the technology's potential to vaporize asteroids.


Whenever people see pictures in space it tugs on some core Philip Lubinpart of them that wants to explore. What we’re looking at are practical approaches to get to high enough speeds to enable a practical mission to the nearest star. It’s obviously a bit futuristic but we think it’s actually do-able as a 30 – 50 year class program.

The basic issue is that if you look at what we do in the laboratory, we can very easily get to the speed of light - literally within 1m per second. And if you look at what we do with chemical propulsion, such as with cars, jets, rockets, you name it, we get to a very tiny fraction within the speed of light.

So the question is, why you can’t do what we do in the laboratory but on larger scales. And that is really the basis of what we’ve been working on for a number of years.

What we’re proposing is you use directed energy systems to propel spacecrafts. At first it’d be a very small spacecraft to get to extremely high speeds, but in theory it’d enable getting to the nearest stars in less than a human lifetime. The technology is scalable in the sense that far in the future one could imagine vastly larger systems that could propel extremely large spacecrafts at relativistic speeds. That changes the way you begin to think about travel.

The analogies are important for people to understand the distinction.

When you get a flashlight and you turn it on, or you turn on a room light, the light that comes out is actually pushing back on the device that emits the light. So in the same way that you start a rocket engine and the exhaust comes flying out of the exhaust port in the engine, and the engine moves in the opposite direction. There’s an action and a reaction. The same thing happens when you turn on a flashlight or you turn on a lightbulb: The lightbulb is repelled because the exhaust – namely the photons, the light – pushes it back.

When you increase the power, eventually you get to the point where it’s significant enough to propel. The analogy here then is that if I take a hose and squirt water at a balloon or beach ball, I will push the balloon or beach ball away because the water droplets that hit the ball will impart a force on the ball and they push it. Well, light is like the water that comes out of a hose. They hit an object and if they bounce off the object or are absorbed by the object, they impart a force and that propels the object.

As you increase the amount of power you emit you can get to force levels that are quite large. You can get you can get to acceleration levels and speeds that become a significant fraction of the speed of light. In order to get in interstellar distances in the human lifetime you have to get to get to very high speeds otherwise you’re just not going to get there in time.

The advantage of this approach is that you don’t actually ever carry the engine with you.  The engine stays behind. It’s just that you’re projecting the engine onto the device you’re propelling.

If you want to say what is different now than, say, 50 years ago, or ask why couldn’t we have done this 50 years ago? There’s a couple of answers, but the fundamental one is that we now possess the ability to build large, phase-locked aperture lasers, whereas we could not do that in the past. That requires the technology that’s required to get to relativistic speeds.

The nice thing about what we’re proposing is we build one large driver – the directed energy system. With that one system you can drive an enormous number of robotic missions. It’s truly phenomenal.

If you look at the really small probes that we’re talking about, the really wafer scale probes, it only takes about five minutes or so to get one of those things up to 20 – 30 percent of the speed of light, and then it’s gone. Then you launch the next one. Every five or 10 minutes you can launch a new mission. Just think about that: It means in a day you could launch several hundred missions, a year - 40,000 missions, if you want.

You can send out human-capable missions with this technology. So when we go to Mars, currently we’re sending robots, which is the right thing to do, and then we will follow that with people. I’m very much a booster of sending people to Mars, I think it’s a good thing to do. It’s inevitable – it’s a part of our journey as a species. It’s just that it doesn’t make sense in the systems that we’re talking about to send them to the stars because humans take an incredible amount of support to keep them alive. Not only are humans massive, but they require a large amount of mass to keep them going. To me it makes much more sense to send robots there way, way, way before you ever send a biological system.

One can do this. There does not appear to be a fundamental roadblock as to why we cannot do it.

There’s lots of practical problems to solve – not the least of which is building large structures in space that are required. Launching the requisite amount of materials, improving the lifetime of some of the sub-elements. There’s hundreds, or I could probably list a thousand different problems that need to be solved, but there’s not a fundamental problem. That’s the issue.

That stimulates the human imagination and much of it for me is that. I want to stimulate the human vision, the human imagination.

We can do this. It’s hard, and it’s a long task, but we can do it.

Feature image courtesy of NASA APPEL.