Everything up until now has been background information. It sets the stage for what’s to come; which in this case is Saving Men From Exploding Rockets.
If you recall image from the last post, you might remember (or may, in fact, be currently looking at) a slender needle looking section at the very top of the rocket. Contrary to popular belief, this does not make the rocket more aerodynamic (at least in any significant way). What it does do, and I’ll admit I did not know this until I visited Lockheed Martin, is Save Men From Exploding Rockets.
How do you go about Saving Men From Exploding Rockets? Easy, attach another rocket (preferably not exploding) to them and make that one go faster then the explosion of the current rocket they’re strapped to.
Yup, that’s pretty much all there is to it.
Once the fault is detected, it takes less then a second for the rockets to ignite and start carrying the crew downrange.
In order to get away, you need to be moving fast. Very fast. During abortion, the crew experiences up to 17G’s* and blacks out.
To give you an idea of what 17G’s is, imagine going from 0 to 600 km/h (373 mph) in one second. That’s almost as fast as a speeding bullet .
Last I checked, there are four main thrusters and eight control thrusters. Rockets would actually be a more fitting description since the device is actually a solid rocket motor (SRM).
SRM’s are fire and forget. That is to say that once they fire, you can’t turn them off. Remember your Estes Rockets from way back when? Pretty much just like that.
Most of the time, the crew will never have to use the LAS (at least that’s the plan). When that’s the case, the LAS module is ejected after the crew has reached sufficient altitude that it is no longer needed.
Here’s a video I managed to dig up that shows an example of the launch abort system test:
Hopefully my unwitty series of articles has piqued at least someones interest. If that is the case, you might want to check out George Campbell’s Visual History of NASA’s Project Constellation (Constellation is the overarching name of the entire project).
John Duncan also has a pretty good write up of the old Apollo Launch Escape System, much of which is still applicable in todays system.
*Nitpickers corner: This is actually spread out along all three axes of travel (vertical, forward, and side), so it’s really not that terrible.