Composition of a Comet Poses a Puzzle for Scientists

NY Times ^ | September 7, 2005 | KENNETH CHANG

[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...

[King Prout]

or some WHEN warmer

[King Prout]

huh???

[Unicorn]

Check with Greta

[null and void]

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.

Uh huh, and diamonds can only be formed under high pressure.

(Unless you are growing them commercially in a low pressure chemical vapor deposition reactor)...

[George Oh Well]

"It also seems a bit rash to me to be generalizing data for all Oort and Kuiper objects using data from just one"

Ditto. You know that a Pluto probe goes out next year, right? It's the fastest space vehicle ever made. It'll reach Pluto in 2015, and go on to the Kuiper Belt from there, giving scientists very important data on the early circumstances of life's evolution in the solar system. NASA & planetary scientists are caqlling this "the most important space science project of the next decade".

[mlc9852]

That is exactly what I was thinking! LOL

[akorahil]

Tiamat is around?
Someone get Marduk; his job isn't quite finished...

[null and void]

They're talkin' 'bout you...

[Mikey_1962]

Its obviously an Ice Rink, anyone who loves hockey could have explained this!

GAME ON!

[neverdem]

huh???

Consider it health and science potpourri for my health and science ping list.

I had grief from the admin mods. I was told that I was posting too many stories that required excerpting, and that I should post my health and science stories in chat. In the case of stories that require excerpting, folks have to link to them anyway to read the whole story. I can't enthusiastically post a health or science story to chat. Multiple unrelated links also means I am less likely to be a pest, which means I'm less likely to be asked to delist someone from my ping lists, lists that have only a vague chronological order

[King Prout]

tiamat quit this site: the racism some displayed on Katrina threads was her "last straw".

I wish she'd reconsider.

[null and void]

Damm! I didn't know! I wish she'd reconsider too!!!

I'm gonna miss that Bronze Age Gal.

[GOPJ]

the obvious answer is that it formed somewhere warmer.

Ding, ding, ding. We have a winner...

[vannrox]

Nice post.

It has long been known that our star; the sun, is a fourth generation star. In other words, it was created from the dust and debris of an earlier star. Which, the earlier star, was formed from the dust and debris from a yet even earlier star. Thisstar as also formed from the debris of an earlier star which was formed from a star that was created from the debris left over from the big bang.

By all accounts, each star had planets, as we know know that systems with planetary bodies are quite common.

Why would it be too difficult to understand that one of these earlier planets had life on it? Is it really too difficult to understand the life form that might be billions of years old?

[null and void]

Is it really too difficult to understand the life form that might be billions of years old?

Yeah. Nothing is older than 4004 BC...

[Doctor Stochastic]

For Comparison

[Right in Wisconsin]

God is Life, He's Everything, including a billion years old, and yes He is Alive! So its not to hard to believe "the life form that may be a billion years old." That said, if what you are saying is so obvious, then why wasn't it mentioned by one of the Scientists studying the issue?

[PatrickHenry]

Thanks.

[Bernard Marx]

(Unless you are growing them commercially in a low pressure chemical vapor deposition reactor)...

True. Please help me out with the crystal structure of CVD diamonds. Are they single-crystal cubic?

[null and void]

As far as I know, polycrystalline, grain size in the micron range.

Good for heat spreaders, abrasion resistance, and antistiction coatings.