LOS ANGELES, July 8 (Xinhuanet)-- An immense cloud of fine material was released when the Deep Impact probe collided with the nucleus of comet Tempel 1 on July 3, mission scientists reported on Friday.

    The Deep Impact science team, analyzing data collected during the encounter with the comet measuring 5-km-wide by 11-km-long, said the cloud indicated the comet is covered in the powdery stuff.

     Soon after the 370-kg probe hit Tempel 1 at 10 km per second, evidence of water, carbon dioxide and organic substances spewing from the comet was detected, according to scientists with NASA's Jet Proulsion Laboratory (JPL).

    "The major surprise was the opacity of the plume the impactor created and the light it gave off," said Michael A'Hearn, Deep Impact principal investigator.

    "That suggests the dust excavated from the comet's surface was extremely fine, more like talcum powder than beach sand. And the surface is definitely not what most people think of when they think of comets -- an ice cube," he noted in a statement.

    This probably means the surface material of the comet came together very gently, according to A'Hearn. "If it melted and resolidified, it would have the strength of solid ice."

    "You have to think of it in the context of its environment," said Pete Schultz, a Deep Impact scientist. "This city-sized object is floating around in a vacuum. The only time it gets bothered is when the Sun cooks it a little or someone slams an 820-pound wakeup call at it at 23,000 miles per hour."

    The spacecraft's three imaging cameras shot 4,500 images duringthe encounter, according to the researchers who are looking at everything from the last moments of the impactor to the final look-back images taken hours later.

    "Watching the last moments of the impactor's life is remarkable.We can pick up such fine surface detail that objects that are onlyfour meters in diameter can be made out. That is nearly a factor of 10 better than any previous comet mission."

    The final moments of the impactor's life were important, because they set the stage for all subsequent scientific findings.

    Knowing the location and angle the impactor slammed into the comet's surface is the best place to start. Engineers have established the impactor took two not unexpected coma particle hits prior to impact.

    The impacts slewed the spacecraft's camera for a few moments before the attitude control system could get it back on track. The penetrator hit at an approximately 25 degree oblique angle relative to the comet's surface.

    Then the fireball of vaporized impactor and comet material shotskyward. It expanded rapidly above the impact site at approximately 5 km per second, and the crater was just beginning to form.

    The scientists, still analyzing the data to determine the exactsize of the crater, said the crater was at the large end of original expectations, which was from 50 to 250 meters wide.

    Deep Impact's mother ship, the so-called flyby spacecraft, is now more than 3.5 million km from Tempel 1 and opening the distance at approximately 37,000 km per hour.

    The flyby spacecraft is undergoing a thorough checkout, and allsystems appear to be in excellent operating condition, according to mission engineers.

    The Deep Impact mission was designed to provide a glimpse beneath the surface of a comet, where material from the solar system's formation remains relatively unchanged.

    Mission scientists hoped the project would answer basic questions about the formation of the solar system by providing an in-depth picture of the nature and composition of comets. Enditem