Friday, July 11, 2008

Water on Moon?


The Apollo lunar landings were a gift to science that keeps on giving. Since the lunar surface is not subject to weather or plate tectonics, it gives us a much longer geologic history. The "Genesis Rock" found on the Moon is 4.5 billion years old, nearly as old as the Solar System. In the 1980's, similiarities between lunar ejecta and Earth samples from 65 million years ago led to the theory that an asteroid ended the age of disnoaurs. year 40-50 researchers receive Moon samples for continued experiments.

Prior to Apollo, scientists had no clue what the Moon was made of or where it came from. Today most researchers believe that the Moon was born when a Mars-size object struck Earth and blew off the outer layers. The surviving fragments were big enough to attract each other gravitationally until a single satellite remained. The early Moon was a ball of hot magma, with a lighter crust that became the lunar highlands. The lunar "seas" are seen as erupted materiel from the interior. The Moon formed much closer to Earth, and has been drifting away due to tidal forces.

In a study published this week in NATURE, geologist Alberto Saal found evidence of water in Apollo samples. It took 3 years getting the funding to study old rocks, an example of how long good research can take. Using the newer technique of secondary ion mass spectrometry, Saal found traces of volatiles including water. Data showed that hydrogen had been concentrated in the centres of samples, indicating that it dated from the Moon's infancy. Water may even have arrived on the fragments blown from Earth, indicating that our planet had water 4 billion years ago.

As a practical matter, water would make settling the Moon much simpler. It would mean drinks for humans and fuel for Spacecraft. Future Space missions could be resupplied in Earth orbit with hydrogen from the Moon. The Lunar Prospector mission from 1999 found tantalising hints of water ice in the poles. Scientists at ICES last week were itching for the chance to prospect on the lunar South Pole.

Less than a month ago evidence for water was found in The Sands of Mars. Not long ago Earth was thought to be the only watery world. Today there is evidence of H2O in worlds as far-flung as Enceladus and Europa. The dwarf planet (asteroid) Ceres may contain more water that Earth! Water, and possibly other ingredients for life, may turn out to be common in the Solar System.

Human exploration of the Moon has been a huge benefit to science. As mentioned before, the Moon has been slowly drifting away. The Lunar Laser Ranging Experiment from 1969 measures the recession rate as 3.82 cm/yr. Geology and paleontology disagree, measuring recession as about 2.9 +/- 0.6 cm/yr. How can two such precise measurements disagree? If the speed of light is slowing, that will increase the time for light signals to return each year, making the Moon appear to recede faster as seen by LLRE. Starting with GM = tc^3, the prediction is 0.935 cm/yr, precisely accounting for the discrepancy. For measuring small changes in c, it helps to have a long baseline.

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6 Comments:

Blogger robert d said...

"As a practical matter, water would make settling the Moon much simpler. It would mean drinks for humans and fuel for Spacecraft. Future Space missions could be resupplied in Earth orbit with hydrogen from the Moon."

I don't think anyone is postulating that we will ever find usable water on the Moon.

"The Lunar Laser Ranging Experiment from 1969 measures the recession rate as 3.82 cm/yr. Geology and paleontology disagree, measuring recession as about 2.9 +/- 0.6 cm/yr. How can two such precise measurements disagree? If the speed of light is slowing, that will increase the time for light signals to return each year, making the Moon appear to recede faster as seen by LLRE. Starting with GM = tc^3, the prediction is 0.935 cm/yr, precisely accounting for the
discrepancy."

You give a confidence internal for the second value of +/-.6 cm/yr, but no confidence interval for the first value. 2.9 + .6 is rather close to 3.82. Assuming a similar confidence interval for the first value the alleged discrepancy of the "precise" measures is resolved.

Life is good,

d

8:36 AM  
Blogger Seneca the Younger said...

I don't think anyone is postulating that we will ever find usable water on the Moon.

Wow, you're mistaken. See, eg, here.

5:36 PM  
Blogger L. Riofrio said...

Seneca has it right: No one is postulating water, but the data keeps pointing to it.

Error bars on the LLRE measurement are about
+/- 0.02 cm/yr, almost too small to mention and too small to overlap geology's measurement.

7:22 AM  
Blogger nige said...

Thanks for this post Louise. I remember the news about water found at the Moon's poles in 1999.

Away from the lunar poles, the scorching sun combined with the vacuum would boil out and evaporate any water from surface rocks during lunar days, and then freeze-dry the rock during the lunar nights.

But thermal conductivity is low in rocks, so maybe at a suitable depth under the surface where temperature is less extreme (averaged between day and night temperatures), water of hydration exists.

The case for explaining the lunar recession test varying velocity of light is very clear:

"As mentioned before, the Moon has been slowly drifting away. The Lunar Laser Ranging Experiment from 1969 measures the recession rate as 3.82 cm/yr. Geology and paleontology disagree, measuring recession as about 2.9 +/- 0.6 cm/yr. How can two such precise measurements disagree? If the speed of light is slowing, that will increase the time for light signals to return each year, making the Moon appear to recede faster as seen by LLRE. Starting with GM = tc^3, the prediction is 0.935 cm/yr, precisely accounting for the discrepancy."

c = (GM/t)^{1/3}

t = 13,700,000,000 years.

So an increase of 1 year (1 part in 13,700,000,000) will cause the velocity of light to fall according to the equation above by the factor (13,700,000,001/13,700,000,000)^{1/3} = 1.0000000000243. Because the mean distance from the surface of the Earth to the surface of the Moon is 376,000 km, the annual apparent change in distance will be 0.0000000000243*37,600,000,000 = 0.914 cm/year.

This is slightly different from your calculation of 0.935 cm/yr, probably because we took different figures for the Earth-Moon distance. Some sources give the mean distance from the centre of the Moon to the centre of the Earth, others subtract from that the Moon's radius and the Earth's radius. The exact distance depends on where on the Moon the Apollo astronauts left the reflecting mirror in 1969, and where on the Earth the laser pulses are fired from.

It's interesting that there are several pieces of evidence that you have for the velocity of light falling inversely with the cube root of the age of universe.

I hope that you can add this fresh evidence to your main paper on supernovas. It will make it harder to ignore the theory.

8:14 AM  
Blogger L. Riofrio said...

It's interesting that there are several pieces of evidence that you have for the velocity of light falling inversely with the cube root of the age of universe.

Thank you nige, I hope your writings continue to get more attention.

1:47 PM  
Blogger Ed said...

I'm curious. If we know the mass of the universe, then it must be finite. If it is finite, what is outside of it?

1:15 AM  

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