From: gary@ke4zv.uucp (Gary Coffman)
Subject: Re: NASA Coverup
Keywords: More sources for 43,000 mile figure
Reply-To: gary@ke4zv.UUCP (Gary Coffman)
Organization: Gannett Technologies Group
Date: Sun, 8 Nov 1992 22:19:46 GMT

In article <4600@cruzio.santa-cruz.ca.us> snarfy@cruzio.santa-cruz.ca.us writes:
>
>   Let me here define "Neutral Point" :
>
>   The  neutral  point  is  that  point  in a lunar spacecraft's trajectory,
>   measured by the straight line distance from the moon's center  in  miles,
>   where the force of gravitational influence in the direction of the moon ,
>   measured  in  pounds of "pull" on the spacecraft,is equal to the force of
>   influence toward the direction of the earth, also measured in  pounds  of
>   "pull".
>
>   I believe that the direct quotation from the July 25,1969  Time  magazine
>   article would be helpful here:
>
>   "At  a  point 43,495 from the moon, lunar gravity exerted a force [on the
>   spacecraft] equal to the gravity of the Earth , then some  200,000  miles
>   distant."
>
>   I would conclude from the inclusion of the distance remaining  to  go  to
>   the  moon (200,000 miles) that the author knew exactly which units he was
>   talking about .
>
>   I did a search for other sources which would help us analyse just what is
>   meant by " neutral point" , and where  it  might  be  located  along  the
>   flight path of the Apollo .
>
>   In "Project Apollo: Man to the Moon" by Thomas J. Alexander  (Harper  and
>   Row , 1964 ) ,the author states:
>
>   "At  a  point  some  40,000 miles from the Moon ,when the craft is poking
>   along at about 2000 mph, it crosses THE LINE  where  the  moon's  gravity
>   exceeds  that  of  the  earth . That's the second part of the trjectory."
>   (caps mine).
>
>   In  Buzz  Aldrin's  book, "Men From Earth" (1989)  , the author states on
>   page 231:
>
>   "After two full days into the mission we were 150,000  miles  from  earth
>   and   our  speed  was  less  than  3000  miles  an  hour.  The  moon  was
>   approximately 30 hours and 90,000  miles distant."
>
>   Here we have a "horse's mouth" space jockey's description of  his  ship's
>   situation well before reaching either of two postulated neutral points.
>
>    If  we  rule out the possibility that Apollo 11 was undergoing some kind
>   of  continuous  thrusting  which  would  keep  this  3000  mph   velocity
>   constant,we  are then left with the conclusion that the neutral point was
>   approximately 1/2 way between his position at  that  time  and  the  moon
>   which  was  90,000  miles  away.  Here again we arrive at a Neutral point
>   figure close to the 43,595 miles AS SPECIFIED BY TIME , VON BRAUN  ,  and
>   ALEXANDER.
>
>    I  repeat  again  this  is  data  from direct experimental evidence (the
>   actual moon flights) that  the  moon's  gravity  cannot  be  1/6  if  one
>   calculates the relative pulls of the earth and moon based on the proven
>   accurate  inverse square law . In pre - Apollo Astronomy , it is admitted
>   that the exact determination of the moon's mass , therefore the  position
>   of  the  neutral  point  could  not  be determined unless one was able to
>   observe the actual trajectories of lunar spacecraft.

Ah, you've fallen into a particularly common trap. You are taking
simplified "pop" science statements and treating them as if they
meant something else. This is the kind of thing that makes real
orbital mechanics grit their teeth in frustration when they read
them in the papers. All the statements you quote are true in a
limited context, but don't tell the story sufficiently for the
calculations you have attempted. References to speed and distance
in space are of very limited usefulness. You have to ask yourself,
"What component of the velocity vector are they referencing?", and
"Reference to what body is the measurement being made?"

Remember that to reach the Moon from low Earth orbit, we can't travel
in a "straight" line unless we have some magical engine that can thrust
continously. Instead, we do a burn in LEO that changes the shape of our
orbit from a low circular one to a highly eccentric ellipse with it's
low point at LEO and it's high point at Lunar orbit. The point on the
Lunar orbit where the transfer ellipse meets will be empty at firing
time because the Moon is a moving target. Three days later, when the
capsule reaches Lunar orbital height, the Moon will have moved about
it's orbit so that it will be there too. Thus the timing of the firing
is critical. A second burn is then done to transfer the probe from
an elliptical orbit around Earth to a nearly circular orbit around
the Moon, or in the case of Ranger, to a highly elliptical orbit
around the Moon with it's perilune at the surface.

So, since both bodies are in orbits with an intercecting point, you
must always ask when you see speeds quoted, "Speed relative to what?"
The probe is moving along an orbital ellipse with a velocity that
generates the exact amount of centripedal force to cancel the effect
of the Earth's gravity *at every point* in it's orbit barring the
influence of a third body. At any point in the transfer orbit, the
vector component of it's velocity *toward the Moon* is a function of
the geometry of the orbits and the timing along the orbit.

The *neutral point* referred to in this case is the point where the
gravitational attraction of the Moon *adds* just enough to the
centripedal force generated by the probe's motion *along it's orbit*
to warp that orbit toward a Lunar trajectory. Thus this point is much
further from the Moon than your simple "tug of war" analysis would
show because you've neglected the orbital motion of the bodies.

Gary
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