A convenient Gravitational Wave Detector?

A convenient Gravitational Wave Detector?

This is just a general question. I am wondering why the moon can not be
used as a gravitational wave detector.

The moon is in space at some distance from Earth but not too far, and would
be effected by a gravitational wave before the Earth. Surely the moon is
not unaffected by a gravitational wave and given the moon's size, one
suspects that a shape distortion would be of a detectable amplitude.

Apart from the distortion of the shape of the moon (only slightly, but I
assume detectable), wouldn't the moon's position momentarily shift from what
would be expected if simply orbiting the Earth?

The Apollo project still hasn't finished due to an ongoing experiment
initiated by equipment left on the moon's surface - a reflector of some kind
that is used to fix the moon's exact position relative to Earth - could this
be used? Would there be signs of gravitational waves in the data collected
thus far?

Just asking


--
Kind Regards
Robert Karl Stonjek

On Dec 21, 11:12*pm, "Robert Karl Stonjek"
wrote:
A convenient Gravitational Wave Detector?

This is just a general question. *I am wondering why the moon can not be
used as a gravitational wave detector.

Like this?
Gravitational Acceleration of Spinning Bodies
From Lunar Laser Ranging Measurements --K. Nordtvedt
http://arxiv.org/abs/gr-qc/0212043


The moon is in space at some distance from Earth but not too far, and would
be effected by a gravitational wave before the Earth. *Surely the moon is
not unaffected by a gravitational wave and given the moon's size, one
suspects that a shape distortion would be of a detectable amplitude.

Apart from the distortion of the shape of the moon (only slightly, but I
assume detectable), wouldn't the moon's position momentarily shift from what
would be expected if simply orbiting the Earth?

The Apollo project still hasn't finished due to an ongoing experiment
initiated by equipment left on the moon's surface - a reflector of some kind
that is used to fix the moon's exact position relative to Earth -

http://en.wikipedia.org/wiki/Lunar_l...ing_experiment

could this
be used? *Would there be signs of gravitational waves in the data collected
thus far?

IMHO, old microwave horns would work better.
Like one of these:
http://www.bell-labs.com/project/fea...y/penzias4.gif
http://www.bell-labs.com/project/fea...ves/cosmology/ ;-)

Sue...


The origin of gravity
http://arxiv.org/abs/physics/0107015
Breaking Lorentz symmetry
http://physicsworld.com/cws/article/print/19076


Just asking

--
Kind Regards
Robert Karl Stonjek

"Sue..." wrote in message
...
On Dec 21, 11:12 pm, "Robert Karl Stonjek"
wrote:
A convenient Gravitational Wave Detector?

This is just a general question. I am wondering why the moon can not be
used as a gravitational wave detector.

Like this?
Gravitational Acceleration of Spinning Bodies
From Lunar Laser Ranging Measurements --K. Nordtvedt
http://arxiv.org/abs/gr-qc/0212043

RKS:
From what I can gather it looks like there is potential for such
measurements. The paper appears to be more interested in testing theories
of the motion of spinning objects through a gravitational field (where the
spinning object takes a slightly different path to an otherwise identical
but not spinning object).

An accuracy of 4mm is interesting (mentioned in the paper). If detectors
were placed around the horizon of the moon (as viewed from earth) would a
detector on Earth be able to measure a change in the distance between them
eg between the moon's poles and equatorial horizon ie would the longitude
shorten as the latitude widened when a gravitational wave passed the moon?
or is it too rigid relative to the strength of the gravitational wave? or is
the change in dimension too small?)

I imagine a number of small but possibly measurable changes in moon dynamics
occur as a gravitational wave passes it such as a momentary change in the
distance from earth, a momentary change in its orbital speed, and/or a
momentary change in its rotational speed.

If identical synchronised clocks are arrayed across the moon then I'd expect
to see subtle variations in synchronisation as the gravity wave passed
through them. A pulsed laser beam *is* a clock.

Thanks for the links Sue - interesting

Robert



The moon is in space at some distance from Earth but not too far, and
would
be effected by a gravitational wave before the Earth. Surely the moon is
not unaffected by a gravitational wave and given the moon's size, one
suspects that a shape distortion would be of a detectable amplitude.

Apart from the distortion of the shape of the moon (only slightly, but I
assume detectable), wouldn't the moon's position momentarily shift from
what
would be expected if simply orbiting the Earth?

The Apollo project still hasn't finished due to an ongoing experiment
initiated by equipment left on the moon's surface - a reflector of some
kind
that is used to fix the moon's exact position relative to Earth -

http://en.wikipedia.org/wiki/Lunar_l...ing_experiment

could this
be used? Would there be signs of gravitational waves in the data collected
thus far?

IMHO, old microwave horns would work better.
Like one of these:
http://www.bell-labs.com/project/fea...y/penzias4.gif
http://www.bell-labs.com/project/fea...ves/cosmology/ ;-)

Sue...


The origin of gravity
http://arxiv.org/abs/physics/0107015
Breaking Lorentz symmetry
http://physicsworld.com/cws/article/print/19076


Just asking

--
Kind Regards
Robert Karl Stonjek

On Dec 21, 7:12 pm, "Robert Karl Stonjek"
wrote:
A convenient Gravitational Wave Detector?

This is just a general question. I am wondering why the moon can not be
used as a gravitational wave detector.

Strain amplitudes are too small for it to show up in the Earth-Moon
ranging experiments.

The changes in path length are on the order of an atom for the
expected wave sources. Anything detectable by using Earth-Moon ranging
will scream on LIGO/GEO. LIGO has an effective path length of about
600km and still only sees deflections on the order of an atom.


The moon is in space at some distance from Earth but not too far, and would
be effected by a gravitational wave before the Earth. Surely the moon is
not unaffected by a gravitational wave and given the moon's size, one
suspects that a shape distortion would be of a detectable amplitude.

Not a bad idea but this isn't something we could see from Earth at
present. Furthermore, if the Moon is liquid in any way, its' internal
sloshing would swamp out any signal. It is generally assumed that the
Moon is rocky. To my knowledge we aren't sure that it has completely
solidified.


Apart from the distortion of the shape of the moon (only slightly, but I
assume detectable), wouldn't the moon's position momentarily shift from what
would be expected if simply orbiting the Earth?

Technically yes.


The Apollo project still hasn't finished due to an ongoing experiment
initiated by equipment left on the moon's surface - a reflector of some kind
that is used to fix the moon's exact position relative to Earth - could this
be used? Would there be signs of gravitational waves in the data collected
thus far?

The cube corner retroreflectors are still there and are being used.
The Earth-Moon position is known via these ranging experiments down to
the mm level. Unfortunately that is several orders of magnitude too
large to be useful.

The Earth-Moon distance would have to be known to the nanometer level
for that to work. Either that or clone the moon, place it 90 degrees
behind moon #1 and create a Michelson interferometer.


Just asking

--
Kind Regards
Robert Karl Stonjek

Snip
The Apollo project still hasn't finished due to an ongoing experiment
initiated by equipment left on the moon's surface - a reflector of some kind
that is used to fix the moon's exact position relative to Earth - could this
be used? Would there be signs of gravitational waves in the data collected
thus far?

Eric Gisse
The cube corner retroreflectors are still there and are being used.
The Earth-Moon position is known via these ranging experiments down to
the mm level. Unfortunately that is several orders of magnitude too
large to be useful.

The Earth-Moon distance would have to be known to the nanometer level
for that to work. Either that or clone the moon, place it 90 degrees
behind moon #1 and create a Michelson interferometer.


RKS:
One day, but not anytime soon

Robert

On Dec 22, 2:09*am, Eric Gisse wrote:

The Earth-Moon distance would have to be known to the nanometer
level for that to work. Either that or clone the moon, place it
90 degrees behind moon #1 and create a Michelson interferometer.

C'mon! You KNOW that's not a stable orbital configuration!
(Henri Wilson variable stars notwithstanding...)

:-)

Jerry

It is possible to measure the moon distance extremly precize, to be
exactly by a single photon wave...
Or by a radio wave (less distotrion of earth's atmosphere).

The idea is quite simple, like modern (highend) telecommunication
devices who can send singals puls by pulse.
One can send groups of pulses with length variation. example send a
binary primes number wave pulse coded.
Then you can determine exactly how many radio(or photon) waves there
are between the moon and earth.

Altough even waves are bended in a gravity field, but still then you
can determine an exact distance.

I assume but am not entirely sure that this is allready used.
Perhaps not used at astronomy but laser distance measuring is not
something new.
Perhaps using prime paterns (or other paterns) is new, and that would
only make calculations more exactly only more digits. think of
99.9999999% sure that is exactly xxxxxxxx waves. )

wrote in message
...
| It is possible to measure the moon distance extremly precize, to be
| exactly by a single photon wave...
| Or by a radio wave (less distotrion of earth's atmosphere).
|
| The idea is quite simple, like modern (highend) telecommunication
| devices who can send singals puls by pulse.
| One can send groups of pulses with length variation. example send a
| binary primes number wave pulse coded.
| Then you can determine exactly how many radio(or photon) waves there
| are between the moon and earth.
|
| Altough even waves are bended in a gravity field, but still then you
| can determine an exact distance.
|
| I assume but am not entirely sure that this is allready used.
| Perhaps not used at astronomy but laser distance measuring is not
| something new.
| Perhaps using prime paterns (or other paterns) is new, and that would
| only make calculations more exactly only more digits. think of
| 99.9999999% sure that is exactly xxxxxxxx waves. )


HAHAHA!
Suppose you shoot the Moon from the ISS. It takes time
for the signal to reach the Moon, and time to return.
During that time the ISS has moved, so the signal doesn't
have as far to go coming back as it did going if you do
this at moonrise, and further to go coming back if you do it at
moonset. The Moon itself is travelling in an elliptical orbit.
http://antwrp.gsfc.nasa.gov/apod/ap070902.html