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From: tomyee3@gmail.com (ProkaryoticCaspaseHomolog)
Newsgroups: sci.physics.relativity
Subject: Re: Weakness in the results of the three tests of GR shown in rhe lasr
 century,.
Date: Sun, 3 Nov 2024 04:14:28 +0000
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On Sun, 3 Nov 2024 1:15:31 +0000, rhertz wrote:

>> The five operational retroreflectors placed on the Moon during the
>> space race period are _old technology_, have degraded over time, and
>> their placements on the Moon are sub-optimal for ranging purposes. To
>> achieve sub-millimeter ranging to enable improved insights into the
>> Moon's dynamics, internal structure, Earth-Moon system evolution etc.
>> and for improved tests of GR, newer technology retroreflectors and
>> transponders need to be deployed.
>>
>> 1) The old retroreflectors used multiple corner cube prisms arranged
>>    on large sheets which flex from differential heating effects,
>>    lowering measurement accuracy. Large single-cube retroreflectors
>>    made from temperature-resistant silica or sapphire would provide
>>    higher reflectivity and stability over time.
>> 2) Active transponders operating in two colors of light would allow
>>    for much stronger return signals and would allow precise
>>    calculation of signal delays from atmospheric refraction.
>> 3) More widely distributed arrays placed with an eye towards improved
>>    lunar science rather than to meet the requirements of manned space
>>    missions would greatly improve LLR measurements.
>>
>> If LLR measurements can be improved to the sub-millimeter or micron
>> level, they will approach the levels of measurement accuracy where
>> alternative theories of gravitation would expect GR to fail.
>
> You shouldn't believe what you wrote, in particular the last part.
>
> You CAN'T TRACK the Moon's ephemeris with such precision for a long
> time. There are MANY PERTURBATIONS that are not contemplated.
>
> Even a solar or galactic fart (cosmic radiation) or the medium term
> influence of Earth's wobbling or other influences from the many bodies
> of the solar system. Even also galactic influences.
>
> You HAVE TO KNOW that the behavior and influence of the great asteroids
> belt is not entirely known, for instance, just to name one source of
> perturbations, even when half the mass is provided by four asteroids.

Next-generation retroreflectors and optical transponders would be able
to track and help characterize the various sources of wobbling, would
they not? They'd do a lot to advance lunar science, serving as probes
into lunar core and inner structure, etc.

If you want to know the contributions of Ceres, Pallas, Juno and
Vesta to the Moon's orbit, you first have to be able to measure their
effects, would you not? Likewise the influence of solar flares and
other galactic farts. :-)

Here is a white paper on next generation corner cube reflectors. It
contemplates ultimate LLR ranging accuracies of ~0.1 mm.
https://tinyurl.com/yzzvk4sh

This is about the Blue Ghost mission scheduled for Q4 2024:
https://fireflyspace.com/missions/blue-ghost-mission-1/

I couldn't find the paper that I had read about dual frequency optical
transponders on the Moon. But even as dual frequency GPS provides
dramatically improved positioning, dual frequency optical transponders
should dramatically improve range determination.

Moreover, instead of ranging the Moon from a limited number of large
observatories, optical transponders would open up observations to
even modest sized scopes.