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View Diary: Can we stop an object from hitting the earth? (108 comments)

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  •  You keep an inventory of weapons in orbit (0+ / 0-)

    at all times.

    It is very difficult to see the de-orbit burn, especially during daylight hours.

    Yes, it would be very difficult to hit a moving object. Aircraft carriers do not move very fast and maybe just hitting the water near it may be enough to sink it.

    The only military laser that I know of with the capabilities that you mention was the size of a Boeing 707 and could only be fired once without refueling.

    •  Okay, reality check (2+ / 0-)
      Recommended by:
      Dumbo, Calamity Jean

      Dropping things from orbit is an incredibly stupid weapons systems, for several reasons.

      1. It's a system that everyone can see, all the time, and know exactly where it is. And if you know where it is, you know what it could hit, and when, at any given time.

      2. It's a weapon that everyone and their dog can see coming. You can't hide it. If you do a powerful de-orbiting burn, that makes it easy to detect and determine it's probable impact point. If you do a low power burn to try and make it less noticeable, that means an enormous lead time to track separation...and determine the probable impact point.

      3. If you're using kinetic energy, that means the object is coming in fast, but because it's coming in fast that means it's surrounded by a plasma sheathe that prevents communications or sensors from adjusting it's course other than what it was programmed. You know those few minutes of silence during the Apollo re-entries when they lost the data feed and communications? Same thing. Which means for the last few minutes of its flight the projectile can't change it's target.

      Oh, and that plasma sheathe? Reflects radio waves like you wouldn't believe, which means you get a track on it almost immediately.

      At 30 knots (aircraft carrier cruising speeds), an carrier is moving over 50 feet a second, which means that if you have a three minute blackout window, the carrier will have moved almost two miles, or it might have altered course and be somewhere else.

      Basically, it's a stupid ass weapons system.

      •  I would have rec'd you 'cept for that last line (0+ / 0-)

        Now I'm considering a hide rating.

        Even Democrats can be asses. Look at Rahm Emanuel.

        by Helpless on Fri Feb 22, 2013 at 03:50:07 AM PST

        [ Parent ]

      •  It also is terribly expensive. (0+ / 0-)

        It also is terribly expensive in terms of energy.

        We think of "dropping" thigs from orbit. We detach them from our satelite and they just drop to Earth. Reallu, anything we detach from our satelite will just follow along with it. Verne, wh got so much wrong in From the Earth to the Moon, got that right.

        What you have to do to hit simething is fire a braking rocket to cut it's velocity to the point that it enters the Earth's atmosphere. Then, the atmosphere brakes it further, and that makes its trtajectory somewhat unpredictable. Hitting Texas by dropping something from orbit woulldn't be hard. Hitting Dallas would take a lot of practice. Hitting a single building would be impossible.

        The artillery and rockets we have on Earth are much more practical.

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