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A mass driver is a proposed device for propelling objects by using electromagnets. It was first conceptualized in the 1970′s as a possible method to launch rockets into space but still has to come into fruition. Think of it as a linear accelerator directed to the cosmos which, instead of propelling subatomic particles, can shoot large objects.
A typical mass driver will launch an object at very high velocities. After leaving the mass driver, the object will then act as a freely falling body. That is, aside from air resistance, the only substantial force acting on it will be that of gravity. Therefore, in order for it not to be pulled back to the ground, its launch velocity should really be extremely high.
This is one of the reasons why mass drivers are deemed unsuitable for earth-based launches. The rocket, as well as everything inside it, will be subjected to very high g’s. Thus, the trip can end in a disaster before the rocket can even reach its destination. High g’s can be hazardous to human passengers and damaging to sensitive equipment.
Such problems are not present in low-gravity conditions though. Therefore, moon-based or spacecraft-based launches can make use of these contraptions more successfully. All you’ll need is a considerable source of energy, like a nuclear reactor.
Talking about spacecraft-based mass drivers, you can actually use these contraptions to work the other way around. Alright here’s the basic idea: recall Newton’s 3rd Law a.k.a. the action-reaction law. If we take a closer look at any launch scenario or even the manner by which rockets or jet planes move forward, we can easily recognize the action-reaction law at work.
That is, a rocket is propelled forward by pushing some reaction mass backward, much like what happens when you throw a really heavy rock – you get pushed back slightly. If you are somehow able to duplicate that feat in outer space, the absence of friction will allow you to be pushed back much easier.
Thus, if we can attach mass drivers to asteroids, we can slowly change their trajectories by shooting out reaction masses into space. Where to get the reaction masses? Why, the asteroid itself can be your source. Chip off huge chunks of the asteroid and load them into your device.
Think Armageddon and Deep Impact. With this technology, you’ll have an alternative plan to simply just blowing up the asteroid or comet. Of course, that will prevent Bruce Willis wannabes to perform their heroic deeds and a dramatic ending.
We’ve got a few articles that touch on mass driver here in Universe Today. Here are two of them:
NASA also has some more related articles:
Tired eyes? Let your ears help you learn for a change. Here are some episodes from Astronomy Cast that just might suit your taste: