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roidspop
2002-Mar-21, 04:05 AM
I got sucked into trying to correct a crank's idea that lunar gravity was anomalously high. So I found some Apollo video clips and did a little analysis. I'm getting crud (like 0.16 to about 0.24 gee) because of limitations to my ability to measure distances, but given that, I guess the results are fair. But this guy has taken off to the races with the cruddy results...he doesn't have a site, but he corresponds with others who do, so perhaps I should apologize in advance. But better; if you have knowledge of a site that gives the exact dimensions of an Apollo PLSS, that would be a great way to correct this mess...or is it ever possible to correct something like this? Oh well.

JayUtah
2002-Mar-21, 04:49 AM
I'll see if I can look up the PLSS dimensions. In the meantime,

http://www.clavius.org/photlens.html

might be able to help you measure objects and distances in photos.

If your interlocutor is determined to find some reason for not listening to you, then there is little you can do to recover from a mistake. You must simply accept that he is willing to tolerate the gravest errors from hoax authors, but none whatsoever from you.

As for the "massive moon" theory, we can measure, to some extent, the gravity of the moon from here on earth. If it were something significantly different from 1/6 g, the world would have known about it long before Apollo.

You can, if you wish, measure the length of time John Young is in the air during his famous "jump salute" and from that determine the acceleration of gravity. This will give you the strength of the moon's gravity.

2002-Mar-21, 08:28 AM
PLSS
I do not know what those4 letters mean .1
http://www.clavius.org/photlens.html
and will be of little help at all
my approach would be Apollo 11
Command module orbital period
the "We reach the Moon" ref book I use
says orbit #24
so i'd begin with 24 and work backwords
some way.

this makes no sence whatso ever
so even I won't attemt that! good luck with the lottery anyway

Magnificent Desolation
2002-Mar-21, 09:51 AM
On 2002-03-20 23:05, roidspop wrote:
(.........) But better; if you have knowledge of a site that gives the exact dimensions of an Apollo PLSS, that would be a great way to correct this mess...or is it ever possible to correct something like this? Oh well.


I believe that this link will do the trick:

http://www.apollosaturn.com/Lmnr/p.htm

Quote: "The life support pack, with its controls, weighs 104 pounds; it is 26 inches high, 20.5 inches wide and 10.5 inches deep. It is powered by a 16.8-volt silver-zinc battery. A fiberglass cover protects the pack against micrometeroroids."

"Magnificent Desolation"

NottyImp
2002-Mar-21, 11:51 AM
"I'm getting crud (like 0.16 to about 0.24 gee)"

These don't seem like cruddy results to me at all. The moon's gravity is 1/6 g, and that is very close to 0.16. Could you do an error analysis on your calculations to show the approximate nature of your calculations? Perhaps a mean value, with error might help? I doubt your friend will listen, given what you say however.

JayUtah
2002-Mar-21, 02:10 PM
PLSS I do not know what those 4 letters mean

Portable Life Support System. This is the lower segment of the backpack assembly, the top segment being the Oxygen Purge System. Both are sometimes collectively described as the PLSS, pronounced "pliss".

http://www.clavius.org/photlens.html
and will be of little help at all

Perhaps not. The poster seemed interested in measuring objects in photos, and with a bit of photogrammetry the theoretical lens model is frequently helpful, but never sufficient; you need a reference of known size (e.g., the gnomon).

roidspop
2002-Mar-22, 03:56 AM
Thank you for all your help! Amazing!

I am still not getting good results with this, (don't tell anybody, but 0.26 gee is pretty popular). The distance measurements, even with the good dimensions for the PLSS and OPS are still flakey. I will revisit John Young's jump with these new figures and hope they produce better results than I'm obtaining from Scott and the hammer. This seems, at first glance and to a rank amateur, like a very simple exercise and it turns out not to be at all.

I really appreciate your contributions.

JayUtah
2002-Mar-22, 04:10 AM
You should get values right around the 0.16 range. If you're using the PLSS as the reference object for scale, be sure you add in the OPS measurements. The measurements given above are for the PLSS only and do not include the OPS atop it. The OPS is 10 inches tall. The back pack as worn includes both the PLSS and the OPS.

roidspop
2002-Mar-22, 04:40 AM
Using a combined height of about 36", I am getting values of about 0.18 gee, which is good enough for government (conspiracy) work. I doubt that the dimensions I was referred to include the covering...I will look again and see what that might amount to.

I have pointed out to these individuals, who among other things, insist that the moon has a palpable atmosphere, that they might observe the behavior of the dust thrown up by the astronauts and their vehicles. Hardly the sort of thing you'd ever seen in air. Given photogrammetry of the sort I can't perform, I'm sure you could get lunar gee from those arcs of dust.

Thanks for your help.

AstroMike
2002-Mar-22, 05:21 AM
There's actually a formula you can use:

g (acceleration of gravitation) = mass of (kg) radius (km) squared G (gravitational constant = 6.67259 <sup>-11</sup> N m<sup>2</sup>kg<sup>-2</sup>}

The Moon's mass is 7.35<sup>22</sup>kg, and it radius is 1,738 km.

Radius squared is 3,020,644.

7.35<sup>22</sup> 3,020,644 = 2.433255955<sup>16</sup>, 6.67259 <sup>-11</sup> = 1623611.935. Divide by 1,000,000 for m/sec<sup>2</sup> = 1.623611935 m/sec<sup>2</sup>.
Earth's g is 9.80665 m/sec<sup>2</sup>.

1.623611935 9.80665 = 0.165562341 (Moon's gravity compared to Earth).

Pretty neat, huh?
_________________
"The contemplation of celestial things will make man both speak and think more sublimely and magnificently when he descends to human affairs." -Marcus Cicero

<font size=-1>[ This Message was edited by: AstroMike on 2002-03-22 00:25 ]</font>

JayUtah
2002-Mar-22, 01:53 PM
AstroMike, the problem with this computation is that the "Massive Moon" theorists (disciples of William Brian, mostly) argue that we've been told the wrong values for the mass of the moon, that it is actually much more massive than the values we read in our astronomy books. So while your math is acceptable to the mainstream, it does nothing to dispute the point because it's based on the estimate of the moon's mass they say was simply invented to satisfy this calculation.

The Massive Moon theorists go on to claim that because the moon is so massive, there is no reason it can't have an atmosphere.

0.18 g is an acceptable value given the limitations of measuring trajectories and timings from poor quality video.

The problems with the Massive Moon theory are chiefly empirical. If the moon were really so massive (ca. four times as massive as estimated) then it would wreak havoc with earth tides. It would also noticeably perturb the orbits of just about everything in orbit around the earth, especially communication satellites.

The Massive Moon theory traces its lineage to a single faulty computation by William Brian, which unfortunately is a very common mistake, made even sometimes by otherwise knowledgeable people. Ask yourself who is wrong: William Brian, whose proof has already been discounted, or the tens of thousands of astronomers and rocket scientists all over the world who carry out space operations on a daily basis using the published values?

AstroMike
2002-Mar-22, 11:43 PM
Hmm. I think I'll go with my astronomy books instead of someone who knows very little about physics.
http://nssdc.gsfc.nasa.gov/imgcat/hires/hst_pr94_17.gif
Pluto and its moon Charon from the HST.
Charon is about half Pluto's diameter and one tenth its mass, about the equivalent of Mars is to Earth. In fact, Charon is so big compared to Pluto that it doesn't exactly orbit it. The two bodies orbit around a barycenter, swinging each other around it.
If the Moon's gravity is 0.64 as Brian says, it must be more than half Earth's size, which means it would orbit around a barycenter like Charon does.

roidspop
2002-Mar-23, 02:52 AM
AstroMike, it is as JU says; these jokers don't believe in G and Newton is a hissing and a by-word to them, so there was no point in trying to calculate the value from UG. Instead, I attempted to do a simple measurement and analysis with grade-school math that would produce results that might provoke some of these characters into attempting to refute me by doing the work themselves. Well, it seemed like a good idea. One of them, surprisingly, is apparently learning a bit about orbital mechanics, so maybe the effort was not totally wasted. But the rest seem to be caught up in their poetic conceit and none of this number-flogging will stir them.

AstroMike
2002-Mar-23, 03:21 AM
On 2002-03-22 21:52, roidspop wrote:
AstroMike, it is as JU says; these jokers don't believe in G and Newton is a hissing and a by-word to them, so there was no point in trying to calculate the value from UG.


Oh OK. I guess there's no point arguing with people who doesn't believe in Newtonian physics in the first place.
_________________
"The contemplation of celestial things will make man both speak and think more sublimely and magnificently when he descends to human affairs." -Marcus Cicero

<font size=-1>[ This Message was edited by: AstroMike on 2002-03-23 11:22 ]</font>

GrapesOfWrath
2002-Mar-23, 07:48 AM
If the Moon's gravity is 0.64 as Brian says, it must be more than half Earth's size
That doesn't necessarily follow. The moon's gravity on the surface is about 1/6 that of Earth's, but its mass is less than 1/80.

2002-Mar-23, 11:45 AM
<a name="20020323.5:34"> page 20020323.5:34 aka rate of change
On 2002-03-21 09:10, JayUtah wrote: To: 4 IX 12 CUMKU
PLSS I do not know what those 4 letters mean

Portable Life Support System. This is the lower segment of the backpack assembly, the top segment being the Oxygen Purge System. Both are sometimes collectively described as the PLSS, pronounced "pliss".
LM News Reference: Portable Life Support System (p11 of 11)
LM News Reference: Portable Life Support System
http://www.apollosaturn.com/Lmnr/p.htm
ouch which is carried on the PLSS
this post will change slowly & by the new
Mayan Month should be something else again.
5:37 A.M.

2002-Sep-16, 02:42 AM
600/20 = 30 days / page or page / Month approx
On 2002-03-23 06:45, HUb' wrote: To:
<a name="20020915"> page 20020915 aka dredged from PAGE 20 915-323=592 days OLD





LM News Reference: Portable Life Support System
http://www.apollosaturn.com/Lmnr/p.htm


Mayan Month should be something else again.

http://www.clavius.org/photlens.html