Posted on 09/07/2005 12:10:01 PM PDT by neverdem
Although comets form at the frigid edges of the solar system, they appear somehow to contain minerals that form only in the presence of liquid water, and at much warmer temperatures, scientists are reporting today.
On July 4, as planned, part of the Deep Impact spacecraft - essentially an 820-pound, washing machine-size bullet - slammed into the comet Tempel 1 at 23,000 miles an hour. The collision tossed up thousands of tons of ice and dust from the comet that were observed by telescopes on Earth as well as small flotilla of spacecraft.
One of the observers was the Spitzer Space Telescope, a NASA mission that takes pictures in the infrared part of the spectrum. In the burst of light after the collision, Spitzer detected specific colors of infrared light that indicated that Tempel 1 contained clays and carbonates, the minerals of limestone and seashells.
Clays and carbonates both require liquid water to form.
"How do clays and carbonates form in frozen comets where there isn't liquid water?" said Carey M. Lisse, a research scientist at the Applied Physics Laboratory at Johns Hopkins University who is presenting the Spitzer data today at a meeting of the Division for Planetary Sciences in Cambridge, England. "Nobody expected this."
Spitzer also detected minerals known as crystalline silicates. Astronomers had already known that comets contain silicates, but silicates line up in neat crystal structures only when they are warmed to 1,300 degrees Fahrenheit - temperatures reached at around the orbit of Mercury - and then cooled.
"How do you do that and then how do you put that stuff into a comet that forms out by Pluto?" Dr. Lisse said.
Dr. Lisse said that the presence of the clays, carbonates and crystalline silicates indicated that material in the solar system's primordial cloud had somehow...
(Excerpt) Read more at nytimes.com ...
But a single crystal diamond substrate can be used as a template for further single crystal growth in which the synthetic grows with the same crystallographic orientation everywhere on the substrate. (I don't know how they get those substrates but they do). If it's grown to great enough thickness the diamond produced this way can be polished into faceted stones. I just couldn't recall the details.
Ah. My interest was from an engineering materials standpoint. Thanks for the additional information!
Various "scientists" each have their own areas of expertise. A astrophysicist who studies the chemical makeup of stars has a background completely different than an geologist. Actually, scientists are very conservative, and would do their best downplay the discovery. I gather most of the "scientists" are really engineers who are analyzing the data. So any information is most certainly downplayed.
ping
third of four
Phase diagram of water revisedSupercomputer simulations by two Sandia researchers have significantly altered the theoretical diagram universally used by scientists to understand the characteristics of water at extreme temperatures and pressures. The new computational model also expands the known range of water's electrical conductivity. The Sandia theoretical work showed that phase boundaries for "metallic water" -- water with its electrons able to migrate like a metal's -- should be lowered from 7,000 to 4,000 kelvin and from 250 to 100 gigapascals. (A phase boundary describes conditions at which materials change state -- think water changing to steam or ice, or in the present instance, water -- in its pure state an electrical insulator -- becoming a conductor.) The lowered boundary is sure to revise astronomers' calculations of the strength of the magnetic cores of gas-giant planets like Neptune. Because the planet's temperatures and pressures lie partly in the revised sector, its electrically conducting water probably contributes to its magnetic field, formerly thought to be generated only by the planet's core. The calculations agree with experimental measurements in research led by Peter Celliers of Lawrence Livermore National Laboratory.
PhysOrg
Thursday, October 5, 2006
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