Tag: Aerospace Engineering

Science Sunday: Warp Drives

(Again, a bit late. But it’s still Sunday somewhere, right?)

One of the biggest problems facing space travel is that it is ridiculously expensive. Not just in terms of money, but in terms of fuel. Conventional rockets are wonderful but they require enormous mass to generate thrust. One of the reasons the Saturn rockets were so massive was not just because of the enormous amount of fuel needed to leave Earth orbit but the enormous amount needed to lift that enormous amount of fuel. And if you wanted to make a round trip to, say, Mars, you’d have to take gigantic quantities of fuel with you. Your cargo would be a few people, some food and water and vast amounts of rocket fuel.

There are many ways to overcome this. Some of our spacecraft now use ion thrusters, which are efficient but can’t produce the kind of impetus you need to reach orbit. Our spacecraft frequently used gravitational slingshots, essentially borrowing a tiny fraction of a planet’s orbital energy, to reach the outer parts of the solar system. There have been proposals for space elevators and magnetic catapults.

Well, how about warp drives?

Over the last few weeks, people have been getting excited about the idea that NASA has discovered a warp drive, which could open vast areas of the universe for exploration at a tiny fraction of the cost we’re paying. Well, I hate to throw cold water on it but science is nothing if not a cold water thrower:

Last year, the Eagleworks lab—headed up by Harold “Sonny” White—said at a conference on propulsion technologies that they had measured thrust from an electromagnetic propulsion drive. The basic idea behind an EM drive, which is based on a design from a British engineer named Roger Shawyer, is that it can produce thrust by bouncing microwaves around in a cone-shaped metal cavity.

That would be awesome, of course, except it violates one of the fundamental tenets of physics: conservation of momentum. Saying that a drive can produce thrust without propellant going out the backside is kind of like saying that you can drive your car just by sitting in the driver’s seat and pushing on the dashboard.

Now, the last time this idea popped up it made a bunch of noise, which eventually settled down because of some pretty (ahem) obvious flaws in Eagleworks’ experiments. The physicists hadn’t run the tests in a vacuum—essential for measuring a subtle thrust signal. And while they had tested the drive under multiple conditions, one of them was intentionally set up wrong. That setup produced the same thrust signatures as the other conditions, suggesting that the signals the physicists were seeing were all artifacts.

This time around, Eagleworks researchers said they had addressed one of those problems. “We have now confirmed that there is a thrust signature in a hard vacuum,” wrote Eagleworks member Paul March in a forum. It was that post—all the way back in February—that led to most of last week’s hullabaloo.

So, the Eagleworks people have eliminated one of a myriad of problems with their experiment. But many remain, the work is unrefereed and, even if its real, we’re talking about very very tiny amounts of thrust that is barely above the detection threshold.

In other words, it sounds an awful lot like cold fusion. I’m glad someone is researching far-out ideas for changing space travel. But we shouldn’t mistake it for a breakthrough until there’s an actual, you know, breakthrough.

(These are the same guys who circulated an artist’s conception of a warp drive ship that many outlets mistook for an actual design from NASA.)

Right now, there is simply no way to make space travel easy. It would be nice if we could work an alternative. But so far, no luck.

(PS – If you want to see a movie that addresses issues of space travel in an interesting way, check out Interstellar.)