NASA's biggest problem

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Simon has a way of making things clear to me, and this post is no different. Love the diagram.

Why Rocketry Doesn't Work in the Vacuum •


Perhaps the most common question inquiring minds have about space travel is: 0;how can rockets function in the vacuum of space – or in very thin air pressure”? To this question, (and its believers) unfailingly respond roughly like this: “that’s because rocket thrust is not achieved by pushing against air. Air has little or no influence on rocket propulsion. What makes a rocket move is the rocket fuel pushing onto itself. Have you ever heard of Newton’s 2nd & 3d laws of motion?” Well, the claim that “air density has NO influence on rocket propulsion” has to be the silliest of all NASA lies.

via Why Rocketry Doesn’t Work in the Vacuum •

2 thoughts on “NASA's biggest problem

  1. larry

    I have been considering joining CF to respond to this thread. The claim that the “free expansion of gas into a vacuum” proves the impossibility of rocket thrust in space is bogus. This model would be valid if the rocket engine was enclosed by a box which is attached to the ass end of the rocket. Obviously wouldn’t work.
    In fact, a rocket would work better in no atmosphere. Imagine yourself on roller skates firing a shot gun. What would happen? Everyone would guess (I believe) that you would move in a direction opposite to the shot gun slug flying away. It’s hard to imagine how air pressure or resistance acting on the slug would have any effect on you. What’s happening is that momentum is conserved. Momentum is mass times velocity. When you and the slug were at rest, lets call the total momentum for you and slug both zero. (m1 x v1) + (m2 x v1) = 0 . After the shot gun is fired, the momentum for the slug is m1 x v2, where v2 is the new speed of the slug. For the total momentum of the system to be the same, m2 x v3 = – (m1 x v2), or v3 = – (m1 x v2) / m2, where v3 is the new velocity for the shooter. If you were falling in space, with no atmosphere, v2, the speed of the slug would be greater with no air resistance impeding it, so v3 would also be greater in the opposite direction.
    BTW, I don’t believe that there is anything man made functioning in space. As alluded to on CF, the radiation problems are immense. Not to mention that the speed required to stay in orbit is many times greater than the fastest speeding bullet, so hitting a spec of an asteroid, which might be coming from an opposing direction at a comparable speed would be highly problematic for the mylar protection. Another problem I haven’t seen mentioned is that if the atoms that are extant within low earth orbit range are ionized, what would that do to the mylar. Or perhaps the radiation would cause the protective mylar to itself become ionized and then simply dustify into atoms, like the WTC.
    I like Simon’s perpetual motion machine. But it wouldn’t work.
    Conservation of energy is the “reason”, but I’ll spare you the details.


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