NASA Briefs Preliminary Plume Findings from Moon Mission Options

[briv1016]

http://www.nasa.gov/home/hqnews/2009/nov/H...S_briefing.html

[Fran Ontanaya]

It could be from the strength of the spectral signal against the background.

They said 100kg is the estimated lower limit in the field of view. Many volatiles were quickly vaporized and expanded away.

[centsworth_II]

It could be from the strength of the spectral signal against the background.

Right. I thought the 100kg was an estimate of what was actually seen in a narrow field of view and that they are not ready to estimate what was in the entire plume or in the entire excavated area.

[Guest_Zvezdichko_*]

Right. I thought the 100kg was an estimate of what was actually seen in a narrow field of view and that they are not ready to estimate what was in the entire plume or in the entire excavated area.

I already see a discussion on what 100kg means is going on. 100 kg per 20x20kms crater means it's quite dry. But a narrow field would require a whole new line of calculations and investigations, which I don't see it will happen in the next several weeks.

[P Hayne]

I already see a discussion on what 100kg means is going on. 100 kg per 20x20kms crater means it's quite dry. But a narrow field would require a whole new line of calculations and investigations, which I don't see it will happen in the next several weeks.

The crater diameter is about 20 meters. This gives roughly 1-10 ppm water by volume, if 100 kg represents the total amount of H2O in the ejecta (which is uncertain).

( 3.14*(10 m)^2 * (2 m) = 10^4 cubic meters; (100 kg H2O) * (1 m^3 / 1000 kg) = 0.1 cubic meter H2O; (0.1 cubic meter H2O) / (10^4 cubic meters total) = 10^-5 = 10 ppm H2O )
( changing the depth-to-diameter ratio from 1:10 to 1:5 gives roughly 1 ppm H2O. )