nick c wrote:It is important to note that the EU does not preclude the existence of water on comets or asteroids. Comets are objects, regardless of their composition, defined by their electrical state due to elliptical orbits.
Water on comets is in no way a test of the Electric Comet model. The essential test is whether or not the coma and tail are the result of the electrical interaction of the surface with the solar wind and not from sublimating ices.
Yes, but how do you suggest they test this idea? All of the ices can be in the interior and escaping to the surface to cause the coma, as assumed by the new dirty snowball model. How can you prove that water is not on the inside of the nucleus from only exterior observations? Even if the comet broke up near perihelion, the EU would expect water production as will the snowball model. Maybe after perihelion if the water production is increasing as the comet moves away from the sun into a colder area, some questions will be taken seriously regarding the sublimation mechanism.
My point was that the presence of water on or inside of a comet is not a test of the EU comet model, as we would expect to find (if we looked at enough comets) some icy bodies. However, the absence of ice on or inside of a comet would falsify the dirty iceball model as there would be no explanation for the existence of a coma and tail. The sublimation model has no means of explaining a comets coma and tail if there is at least one comet without any ices or enough to produce the observed coma and tail.
As things stand right now all of the comets that have been visited seem to be rocky bodies. The data received from these probes is consistent with the electric comet model as proposed before the probes arrived. That is, the model has not had to be modified after the results were in. The dirty snowball/iceball model had to be radically revised because it predicted a loose conglomeration of ices. When that was not found the model was modified to put the ice "hidden" in the interior. Of course, modifying a theory to accommodate new data/observation is part of the scientific method, but it does indicate that the iceball theory may be in trouble. Especially when the presence of water in the coma and tail can be explained by other means.
I do not see any difficulty in testing the EU model should it be given a priority by the ptb. I am sure that the skilled people at NASA or ESA could equip any number of data gathering equipment on a future comet probe that would be designed to specifically test the model, if they so desired. The problem is that they are not designing equipment with the EU model in mind. That is why the Philae lander was equipped with ice screws and harpoons designed to hook into the ice.
The process of protons from the solar wind interacting with oxygen released from the comet's rocky surface and combining to form water molecules (mostly hydroxyl) has been observed on the Moon. Why would not the same process account for the water in the coma and tail of comets? As has been pointed out before in this forum, but it needs repeating, NASA is aware of this process as well as the implications for the icy comet theory:
The assumption of ices as important bonding materials in cometary nuclei rests in almost all cases on indirect evidence, specifically the observation of atomic hydrogen (Lyman [Greek letter] alpha emission) and hydroxyl radical in a vast cloud surrounding the comet, in some cases accompanied by observation of H20+ or neutral water molecules. In addition, CH3CN, HCN, and corresponding radicals and ions are common constituents of the cometary gas envelope. These observations can be rationalized by assuming (Delsemme, 1972; Mendis, 1973) that the cometary nuclei consist of loose agglomerates containing, in addition to silicates (observed by infrared spectrometry (Maas et al., 1970)) and also water ice with inclusions of volatile carbon and nitrogen compounds.
It has been suggested by Lal (1972b) that the Lyman a emission could be caused by solar wind hydrogen, thermalized on the particles in the dust cloud surrounding the comet. Experiments by Arrhenius and Andersen (1973) irradiating calcium aluminosilicate (anorthite) surfaces with protons in the 10-keV range resulted in a substantial (~10 percent) yield of hydroxyl ion and also hydroxyl ion complexes such as CaOH.
Observations on the lunar surface (Hapke et al., 1970; Epstein and Taylor, 1970, 1972) also demonstrate that such proton-assisted abstraction of oxygen (preferentially O16) from silicates is an active process in space, resulting in a flux of OH and related species. In cometary particle streams, new silicate surfaces would relatively frequently be exposed by fracture and fusion at grain collision. The production of hydroxyl radicals and ions would in this case not be rate-limited by surface saturation to the same extent as on the Moon (for lunar soil turnover rate, see Arrhenius et al. (1972)).
These observations, although not negating the possible occurrence of water ice in cometary nuclei, point also to refractory sources of the actually observed hydrogen and hydroxyl. Solar protons as well as the products of their reaction with silicate oxygen would interact with any solid carbon and nitrogen compounds characteristic of carbonaceous chondrites to yield volatile carbon and nitrogen radicals such as observed in comets. Phenomena such as "flares," "breakups," "high-velocity jets," and nongravitational  acceleration are all phenomena that fit well into a theory ascribing them to the evaporation of frozen volatiles. However, with different semantic labels the underlying observations would also seem to be interpretable as manifestations of the focusing and dispersion processes in the cometary region of the meteor stream, accompanied by solar wind interaction.