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Credit: NASA/JPL. Image manipulation: Carl Smith

This is a sequence of images from the hi-res Deep Impact flyby camera. They show jets emanating
from two centers. The color substitution images on the right show more clearly the relative brilliance
distribution in the grey-scale images. They show the presence of two bright centers. The presence of
more than one crater was predicted by the electrical model of comets.


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Jul 19, 2005
Interim Report on Deep Impact

Though many details remain to be determined, enough data is now in hand to offer a preliminary assessment of our predictions on Deep Impact.

In our Picture of the Day posted prior to Deep Impact we registered the most detailed predictions of any group in anticipation of the event. For their part, NASA investigators made no predictions. Nor can we find in NASA’s subsequent comments any acknowledgement that an independent group had successfully anticipated the greatest surprises of the encounter.

In view of this situation, we consider it essential that the remaining data analysis by NASA not be permitted to lag so far behind the event that no one will notice what has occurred. Nor will it be helpful if the data find their way into the public domain as isolated fragments of technical minutiae.

Therefore, to maintain the integrity of the most fundamental questions we offer the following status report.

Missing Water. Proponents of the electric model predicted that Deep Impact would reveal insufficient water to support the popular ideas about comets. Now we know the ejected material was largely—perhaps entirely—dust and vaporized rock.

Subsurface Composition. We said that the “impact/electrical discharge will not reveal ‘primordial dirty ice,’ but the same composition as the surface.” It is now known that the presence of volatiles in the coma immediately after impact did not change, with the exception of changes relating to charge exchange between the coma and the solar wind (see below).

High-Energy Explosion. Wallace Thornhill claimed that the energy of the “impact” would be greater than expected from impact studies, because of electrical discharge. When the predicted event occurred, it left every NASA investigator stunned.

Advance Flash. Thornhill predicted that a visible discharge between the nucleus and impactor would be likely prior to the impactor’s contact with the surface. At least two flashes are now known to have occurred, though (for the obvious reasons) no one on NASA’s investigative team had anticipated this.

Explosion Temperatures. Though we’ve found nothing from NASA relating to the temperatures of the explosion, we said that the discharge would be “hotter than can be explained by mechanical impact. If temperature measurements are made with sufficient resolution, they will be much higher than expected from impact heating”. On this one we are confident as ever.

Explosion Radiance. Within minutes of the impact, the coma of Tempel 1 was overtaken by a blast of light so great that it saturated the camera’s detectors. NASA spokesmen called this “one of the great surprises” of Deep Impact. The radiance was not expected under the model in use. (See “Fine Dust” below).

Speed of Transport. Electrical theorists suggest that NASA carefully review the rate at which ejecta filled the coma. Could kinetic effects (the effects of physical impact alone) have generated such speeds? Acceleration of negatively charged material is a predictable effect of electric discharge.

System Failure. Our prediction was: “Electrical stress may short out the electronics on board the impactor before impact.” The system did indeed fail a few seconds before impact, and data should be reviewed to look for indications of electrical breakdown.

Multiple craters. We said, “If the energy is distributed over several flashes, more than one crater on the comet nucleus could result—in addition to any impact crater”. Unfortunately, NASA did not anticipate the volume of dust removed by the explosion, which may have made it impossible for even the best enhancement technology to see though the ejecta. However, by tracing rays back to their source we noted the appearance of two ejecta centers immediately after the impact.

Crater Size. We said, “The impact/electrical discharge will be into rock, not loosely consolidated ice and dust. The impact crater will be smaller than expected”. The occlusion of the impact site by the unexpected dust cloud leaves this question of crater size unanswered. (Some NASA investigators have suggested that the impact did not reach a deep level, but so far the pronouncements on the subject are quite contradictory because they’re trying to explain things they did not expect).

X-rays. We suggested that X-rays would accompany discharges to the projectile, “exceeding any reasonable model for X-ray production through the mechanics of impact. The intensity curve will be that of a lightning bolt (sudden onset, exponential decline) and may well include more than one peak”. So far there has been no indication that any instrument based near or on Earth had the temporal or spatial resolution to decide this issue.

Creation of Water in the Coma. The electric model suggests that negatively charged oxygen from silicates and other metallic oxides on the nucleus (a negatively charged object) reacts electrically with the positively charged hydrogen ions of the solar wind to create OH. Thus, readings of the relative abundance of OH should drop in the immediate wake of impact, while in the days after the impact abundances of OH should rise. Though this is inconceivable under the standard model, preliminary data released does suggest this pattern.

X-rays from Coma. Thornhill contends that the electrical transaction between the coma and the solar wind creates the surprising X-rays emanating from cometary comas. Therefore, we should expect that in the days following the impact the x-ray curve will tend to follow that of OH production.

Electrostatic Cleaning and Deposition. In our Pictures of the Day we have noted evidence of both electrostatic cleaning and electrostatic implantation in space. We are confident that both processes occur on the nucleus of Tempel 1. Some of the material cleaned from the surface electrostatically will be accelerated  into space. Other portions of the material, now positively charged, will be electrostatically drawn to the surface.

Collimated Jets. While the electric theorists identify Tempel 1 as a low voltage comet, enhanced pictures should show clearly visible jets retaining their coherence over distances that cannot be maintained by neutral gases in the vacuum of space. All evidence provided to this point confirms the expectation.

Fine Dust. Both the volume of dust and its extraordinarily fine texture have created mysteries for cometologists. The ejected dust appears to be as fine as talcum powder. In no sense was this expected. But it is characteristic of “cathode sputtering”, a process used industrially to create super-fine deposits or coatings from cathode materials.

Surface Geology. We not only predicted the sharply defined relief, but the specific features. “The model predicts a sculpted surface, distinguished by sharply defined craters, valleys, mesas, and ridges—the opposite of the softened relief expected of a sublimating ‘dirty snowball’.”

Surface Arcing. We had seen very small white spots on photographs of comet Wild 2, and interpreted them as electrical arcs in the form of coronal discharges. The highest resolution photographs of Tempel 1, taken by the impactor, show numerous featureless patches of white-out, most located where the electrical hypothesis would put them—on the rims of craters and on the wall of cliffs rising above flat valley floors. This single feature, we believe, provides the “smoking guns” we have waited for. Since their initial suggestion that the patches could be highly reflective spots on the surface, we’ve heard no further comment on the subject. The signature of electric arcing should be clearly evident in the full stream of data now being analyzed.

See also:
Jul 05, 2005  Deep Impact—First Impressions


David Talbott, Wallace Thornhill
Amy Acheson
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