[X] My Assistant

[Fran Ontanaya]

Likewise, there may be some arcane physics -- possibly involving water! -- which accounts for the non-appearance of the ejecta cloud.

Water is important for us, but I feel like it is being portraited as the only kind of solidified substance we would expect to find there besides regular dust.

There is plenty of things that become volatile during the Lunar day and can freeze below 40 Kelvin. Ignoring any other constraints, it could aswell have hit a solid slab of Argon.

[Phil Stooke]

From the Facebook page:

LCROSS Lunar Impactor Mission.
The LCROSS science team met on Saturday and Monday to discuss the results and start putting together the story. In addition, further reports came in from the EBOC (Earth Based Observational Campaign). As true to the scientific method, data has been gathered, positive & null results are both valuable. Now is the time for analysis and comparisons with theory to explain the story. The team anticipates to report at the LEAG in Houston coming up in a few weeks and at the AGU in San Francisco in December. Meanwhile, check our mission page http://www.nasa.gov/lcross for the latest updates.
-LCROSS Facebook Team.

[Ron Hobbs]

Paul Spudis has an interesting take on the potential science at his Air & Space magazine blog:

LCROSS: Mission to HYPErspace

[jmknapp]

Paul Spudis has an interesting take on the potential science at his Air & Space magazine blog:

LCROSS: Mission to HYPErspace

The LRO observations of the impact site show that the LCROSS team made a bullseye, right in the coldest part of the crater. Spudis' claim that a negative water result says nothing, and his trashing of the whole LCROSS concept sounds more like wishful thinking, i.e., we know the water is there somewhere, negative evidence to the contrary notwithstanding. So, rovers and "hoppers" are proposed as the next best hope, that should have been done in the first place, etc.

If no water exists at the coldest part of a permanently-shadowed crater ("cold trap"), by what mechanism would it collect in any appreciable quantity elsewhere?

[djellison]

He was playing devils advocate. If LCROSS turns out dry - then the logical conclusion is to find some other means to explain the Hydrogen reading. The illogical conclusion that may well play out from supporters of the ice hypothesis is that it hit the wrong place and is not a negative. Paul's take on LCROSS is one I share.

[jmknapp]

If LCROSS turns out dry - then the logical conclusion is to find some other means to explain the Hydrogen reading.

Here's an observation from one paper, HYDROGEN MIGRATION TO THE LUNAR POLES BY SOLAR WIND BOMBARDMENT OF THE MOON:

However, the Lunar Prospector
Neutron Spectrometer (LPNS) has detected hydrogen enrichments at both lunar poles (Feldman et al.,
1998; 2000). Although the neutrons are sensitive to atomic composition, the method can not distinguish
between molecular forms of hydrogen. Therefore the hydrogen detected at the lunar poles could be in
hydroxides in the regolith, adsorbed water, molecular hydrogen, or interstitial atomic hydrogen.

In that simulation, they calculate that 7 million years would be required to for the solar wind to transport enough hydrogen to the poles to account for the LPNS reading. That would include atomic hydrogen (2.3%), molecular hydrogen (21.7%), hydroxide (66.7%) and water (6.8%).

[nprev]

Quick disclaimer: I'm not biased towards a wet or dry polar area; let the chips fall where they may based on the evidence.

That said, we need much more data.

This debate strongly reminds me of the view of Mars post-Viking & MPF until the MERs (really, Oppy) & Phoenix: 'dry & rocky everywhere, it's all the same'. This is not a perfect analogy, but the base concept is the same. There seems to be a fundamental human tendency to draw general conclusions based on limited data (call it the 'first impressions' effect?)

Just throwing that out there as a cautionary note. We now return to our regular programming.

[Holder of the Tw...]

One thing I'm not understanding here: why is it so important that the hydrogen has to be present in the form of water to be valuable? These spacecraft are picking up some kind of hydrogen signal. If it's in the form of solar wind deposited hydrogen, then fine. You can roast it out of the rocks and you have your ready made rocket fuel, without the step of having to break it out of the water. If you need water, then just combine the hydrogen with readily available lunar oxygen. And if it's a case of scientific study, well, you just go with whatever is there.

We don't yet know if there is any appreciable water. We do know the hydrogen is there.

[djellison]

We do know the hydrogen is there.

We don't know what form it's in. It may be in a form that's hard to liberate. Furthermore - hydrogen on its own, isn't that useful* It's incredibly light so it's not much of a burden for space flight (consider the Mars Direct ISRU numbers). You tend to need something heavy (oxygen) to do something with it. If it's vast swathes of actual ice down there - then we have rocket fuel, air and water for future crews. If it's just hydrogen, you've still got to take 7/8ths the mass with you.

* apart from filling balloons - but that's not too useful on the moon

[Holder of the Tw...]

But the oxygen is there, too. And there have been lots of studies and pilot projects on how to get it. I still think, that whatever form, suitable seperation techniques would exist to get the hydrogen. Chemically bound to the rocks would be the hardest, but would also seem to be least likely, at least at the poles.

[marsophile]

Some more info here:

http://dsc.discovery.com/news/2009/10/14/l...emperature.html

[djellison]

But the oxygen is there, too.

Good point.

[centsworth_II]

A lot is being made of wishful thinkers' bias in explaining away any negative water results. Maybe Mars first bias explains the speed with with which some are grasping such negative results -- before they are released.

[Juramike]

http://dsc.discovery.com/news/2009/10/14/l...emperature.html

From the article:

"I am preparing a public release that I hope to get out in the next couple of days," lead scientist Anthony Colaprete wrote in an email to Discovery News.

I'm gonna wait for the release...

[Spin0]

Interesting article about water on the Moon: http://www.thespacereview.com/article/1485/1


In 1978 Russians found water in samples brought back by Luna-24. In 1976 Luna-24 landed in Mare Crisium and drilled a core sample from about 2 m deep in Lunar surface. Their article "Water in the regolith of Mare Crisium (Luna-24)" was published in a Russian publication Geokhiimia but seems to have gone ignored.

Here's a link to the abstract: http://adsabs.harvard.edu/abs/1978Geokh......285A

IR diffuse reflection and IR transmission studies of lunar soil samples obtained by Luna-24 are described. Approximately 0.1 wt% water was detected in samples from a depth of 143 cm, and the amount of water seemed to increase with depth, although the extent of change was almost at the limit of technique sensitivity.

Makes it even more sad to think that to day Luna-24 still is the last soft landing on the Moon.