February 4, 2008

• Question 38 - Do rockets launched eastward get a boost from Earth's rotation?

  Question 38 - Do rockets launched eastward get a boost from Earth's rotation?

   

  Robert,
  
  A question came up that I hope you have written about.   I expect to have frequently asked questions with answers on my web site.  This question will be included.
  
  The question involved the launching  spaceships from Florida.  I understand  they tip them eastward.  It is said that the ships gets a boost from motion of the earth. 
  
  Have you written anything about this?  I have the CD and hard copy of your book
  Galileo Was Wrong.
  
  I am hoping you can refer me to where this issue is covered in either form of your book.
  
  Or perhaps you have something you can copy and send to me.
  
  Thanks for what ever help you can give.
  Russ

   

   

  R. Sungenis: Russ, I don’t think we cover the question specifically in Galileo Was Wrong, but we probably should because those who claim that the rocket is going to get a “boost” from launching it eastward are, in the long run, defeating the very thing they are setting out to prove. If the rocket gets a boost from a rotating earth, then this will require that all other things in the earth’s atmosphere will be affected by the same principle. Cannon balls shot eastward should take less gunpowder than cannon balls shot westward to cover the same distance. But that doesn’t happen.

   

  The rocket, before it is launched eastward, is already traveling 1054 mph at the equator relative to outer space. When it is finally launched eastward it will not get any relative “boost” from the Earth’s rotation because the rocket will have to keep up with the ground that is still rotating beneath it at 1054 mph, which will require more thrust than if the Earth were not rotating.

   

  Of course, the real problem with this question is the word “boost.” A boost relative to what? “Boost” implies that there is more ground covered for the same time, or less time flown for the same distance, or less force/fuel needed to cover the same distance or same time. But in order to be an authentic boost, the boost must be measured against some other known and stable position in order to claim you got a boost away from it.

   

  The problem is that, in order to answer this question, people often use an invalid analogy, namely, picturing themselves on a rotating merry-go-round from which they throw a stone tangent to the circumference of the merry-go-round. Now, for a second person who, say, is about a hundred feet away watching you throwing the stone from the merry-go-round, it looks to him as if the stone got a “boost” in its speed from the rotation of the merry-go-round. But that “boost” is only true if it is measured from his position outside the merry-go-round. If it is measured from the within or on the merry-go-round, there will be no boost because, relative to the merry-go-round, if the stone is given the same thrust whether the merry-go-round is rotating of standing still, it will travel at the same speed in either case.

   

  Translating this back to the rocket, if the person wants to say that launching the rocket eastward gives it a boost, he can only do so if he is measuring the “boost” from a position outside the Earth’s atmosphere. For example, if he were standing on the moon and watched the rocket take off eastward from the Earth, the rocket would appear to him to have gotten a boost, because he will see the rocket move away from him faster than if the rocket were launched westward. But this is not really a “boost” in the classic definition of the term; rather, it is an illusion of a boost.

   

  As you can see, all of this is relative, and as such, we can expand the picture to show the validity of geocentrism, for the person standing on the moon watching the rocket on Earth launched eastward cannot tell if it is the Earth’s rotation eastward that makes it appear that the rocket is traveling faster than it would westward, or whether the moon on which he is standing is moving westward at 1054 mph and the Earth is standing still. Both situations will appear to give an illusory “boost” to a rocket launched eastward on Earth.

   

  All in all, the correct answer, if you’re a heliocentrist, is that the rotation of the Earth would have no effect on the rocket. The rocket’s fuel is spent because the rocket is fighting the Earth’s gravity, but gravity has the same force whether you travel eastward or westward, so there would be neither less use of fuel nor a “boost” if one were to launch a rocket eastward on Earth.

   

  Unfortunately, the idea that there is such a “boost” is a myth that has taken on a life of its own. The main reason the US space agency launches rockets from Florida is that, in case there is a mishap during the launch, the likelihood is that it will happen over the Atlantic Ocean and thus no harm will come to civilization.

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