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RGClark
2006-Jan-26, 12:10 AM
NASA Postpones Stardust Mission Media Update.
"NASA has postponed the Stardust comet mission media briefing scheduled
for 1 p.m. EST (12 p.m. CST), Tuesday. The agency plans to allow the
Stardust science team additional time to assess and distribute cometary
samples before scheduling media briefings.
"NASA has enlisted more than 150 experts to accelerate sample studies.
The first samples will be shipped to researchers this week."
http://www.spaceref.com/news/viewpr.html?pid=18821


Will there be found "tar" in the particles? The interstellar dust
collector on Stardust had already found complex organic tar-like
molecules with its CIDA mass spectrometer:

Tarlike macro-molecules detected in 'stardust'
MAX-PLANCK INSTITUTE NEWS RELEASE
Posted: April 29, 2000
"It is the size of these molecular fragments with nuclear masses of up
to 2000 (water e.g. has 18 such units) which surprised us as much as
the seemingly absence of any mineral constituents", explains Dr. Kissel
of the Garching-based Max-Planck-Institut für extraterrestrische
Physik. "Only organic molecules can reach those sizes". The largest
molecules found in space so far are the polycyclic aromatic
hydrocarbons (PAH) which reach masses of a few hundred mass units.
"The details of the mass spectra measured with CIDA show that the
molecules of the interstellar dust must have about 10 percent of
nitrogen and/or oxygen in addition to hydrogen and carbon. This means
that these cannot be pure PAHs, which are planar, but are especially
due to the nitrogen extend into all three spacial directions."
http://www.spaceflightnow.com/news/n0004/29tarstardust/

These "tar-like" particles were presumed to be interstellar because of
their direction and high-speed. However, it is notable that the Giotto
spacecraft also detected "tar-like" materials on the surface of comet
Halley. Perhaps these detected particles arose from comets in other
systems. Another possibility is that the CIDA mass spectrometer
detected particles that arose from jets from comets in our system. That
could explain their high speeds and unexpected directions.
On Earth, actual tar is formed in nature from combustion or decay of
living material:

Tar
http://en.wikipedia.org/wiki/Tar

La Brea Tar Pits.
http://en.wikipedia.org/wiki/La_Brea_Tar_Pits

Even when produced in industry you still need petroleum products or
coal derivatives to produce it, which themselves arise from prior
living material.
If the returned Stardust grains are found to contain true tar that
would suggest they arose from past life in space.

c.f.,

Newsgroups: sci.astro, sci.astro.seti, rec.arts.sf.science,
sci.bio.misc
From: Robert Clark <rgcl>
Date: 2000/04/29
Subject: Re: Tarlike macro-molecules detected in 'stardust' (Forwarded)
http://groups.google.com/group/sci.astro.seti/msg/f42528d44bba448a


Bob Clark

Doodler
2006-Jan-26, 03:34 PM
Dirt. Beyond that, I await the results impatiently :)

RGClark
2006-Feb-18, 05:08 PM
Whatever it is, it's going to be interesting ...

Published online: 13 February 2006
A comet's tale.
"Scientists are just beginning to examine the pieces of a comet brought
back to Earth by NASA's Stardust mission."
...
"After fiddling around to improve the picture slightly, Kearsley starts
a more intensive scan of the grain that will reveal its chemical
make-up. As the analysis comes through, there are cries of surprise.
"Whatever it is, it's weird," says Bland.
"The team agonize over the decision to make another scan to get more
accurate results, but Kearsley is worried about "frying" the sample.
"These grains have had a long journey and rather a lot of money spent
on them," he cautions.
"They can see that just a few minutes exposure to high-energy electrons
has changed the structure of some of the epoxy surrounding the grain,
so they finally decide that the initial results are so astonishing that
they should contact Mike Zolensky at Johnson Space Center immediately
to tell him about the find, and wait for further instructions. Zolensky
is in charge of the preliminary analysis of the samples, and is
collating all the information from these first tests."
http://www.nature.com/news/2006/060213/full/060213-2.html


Bob Clark

Superluminal
2006-Feb-22, 04:09 AM
Seems that they have found heart shaped comet dust.

http://stardust.jpl.nasa.gov/images/tsou060221.jpg

01101001
2006-Mar-13, 09:47 PM
NASA News Release: NASA's Stardust Findings May Alter View of Comet Formation (http://www.nasa.gov/home/hqnews/2006/mar/HQ_06091_Stardust_update.html)


Samples from comet Wild 2 have surprised scientists, indicating the formation of at least some comets may have included materials ejected by the early sun to the far reaches of the solar system.

Scientists have found minerals formed near the sun or other stars in the samples returned to Earth by NASA's Stardust spacecraft in January. The findings suggest materials from the center of the solar system could have traveled to the outer reaches where comets formed. This may alter the way scientists view the formation and composition of comets.

"The interesting thing is we are finding these high-temperature minerals in materials from the coldest place in the solar system," said Donald Brownlee, Stardust principal investigator from the University of Washington, Seattle.

Scientists have long thought of comets as cold, billowing clouds of ice, dust and gases formed on the edges of the solar system. But comets may not be so simple or similar. They may prove to be diverse bodies with complex histories. Comet Wild 2 seems to have had a more complex history than thought.

"We have found very high-temperature minerals, which supports a particular model where strong bipolar jets coming out of the early sun propelled material formed near to the sun outward to the outer reaches of the solar system," said Michael Zolensky, Stardust curator and co-investigator at NASA's Johnson Space Center, Houston. "It seems that comets are not composed entirely of volatile rich materials but rather are a mixture of materials formed at all temperature ranges, at places very near the early sun and at places very remote from it."

One mineral found in the material brought back by Stardust is olivine, a primary component of the green sand found on some Hawaiian beaches. It is among the most common minerals in the universe, but scientists were surprised to find it in cometary dust.

Olivine is a compound of iron, magnesium and other elements. The Stardust sample is primarily magnesium. Along with olivine, the dust from Wild 2 contains high-temperature minerals rich in calcium, aluminum and titanium.

01101001
2006-Mar-13, 11:03 PM
Planetary Society Blog: LPSC, Monday: Notes from the Stardust session (http://www.planetary.org/blog/article/00000490/)


But the most astonishing thing was not the size of the grains, but what they were made of. Many of these largest grains were what mineralogists call "refractory," which means that they formed at high temperatures, temperatures up to 1400 Kelvin or so. Minerals like olivine and pyroxene that we on Earth are familiar with as being the constituents of basalt, the highest-temperature lava that erupts on the surface of the Earth. But remember, these grains were in a comet, which must have formed in the outermost, coldest part of the solar system in order for it to retain its primordial ice. "We have hot minerals in the coldest place in the solar system. Where did they come from? They didn't come from there. They either came from the inner regions of the solar system" meaning the location of the terrestrial planets like Earth and Venus "or from other stars. If this was astronomy, we would stop there, with that question. But we have samples in hand. We will solve the mystery. Stay tuned; and I encourage you to join in the analysis," [Prinicipal Investigator Brownlee] concluded.

[...]

But the more they look at the grains, the more variety they see. Furthermore, not only is there variation from one grain to another, but when they analyze all the little bits of grains that got deposited along those carrot- or turnip-shaped tracks made by the big particles, they find varying compositions along the tracks. For example, Flynn showed one track where they saw iron and nickel deposited pretty much homogeneously along the whole track, whereas zinc was there only along one side of the track, and chromium was there only at the end of the track. Some individual grains have strangely elevated abundances of one element or another. All in all, the composition of the grains is going to be a big, big, long-term analysis project. Some analysis will have to wait for the development of new technology.

01101001
2006-Mar-14, 01:09 AM
NASA TV (http://www.nasa.gov/multimedia/nasatv/index.html)
now (5:08 PST) showing rerun of:


3 p.m. - Stardust Update Briefing - JSC (Interactive Media Briefing) (Public and Media Channels)

It's the Q&A so I (mostly) missed it again.

But, there are 3 more chances on March 14 (times EST):


March 14, Tuesday
12 a.m. - Stardust Update News Conference - JSC (Replay / Recorded 3/13/06) (Public and Media Channels)
2 a.m. - Stardust Update News Conference - JSC (Replay / Recorded 3/13/06) (Public and Media Channels)
4 a.m. - Stardust Update News Conference - JSC (Replay / Recorded 3/13/06) (Public and Media Channels)

01101001
2006-Mar-14, 01:22 AM
From the Nature article (http://www.nature.com/news/2006/060213/full/060213-2.html) cited above:


As the analysis comes through, there are cries of surprise.
"Whatever it is, it's weird," says Bland.
I wonder if that weird stuff was some of those just-disclosed refractory minerals.

Blob
2006-Mar-14, 02:06 AM
Planetary Society Blog:

Hum,
does that imply the young Sun was more volatile (as was suspected) in its youth, or that it was (also) the result of nearby supernova....?

Jerry
2006-Mar-14, 07:26 AM
For example, Flynn showed one track where they saw iron and nickel deposited pretty much homogeneously along the whole track, whereas zinc was there only along one side of the track, and chromium was there only at the end of the track.

So we have iron on the moons of Saturn, thought to have been thrown there from phoebe, and iron in comets thought to have been thrown there by the sun...

Isn't anyone willing to concede that the formation of the solar system may have been along a different path than the consensus model. It is now reasonable to speculate that there are terrestrial quantities of heavy metals in the outer solar system. Dirt, tars, clays, metals, metal salts - earthy stuff.

Blob
2006-Mar-14, 10:04 AM
...the formation of the solar system may have been along a different path than the consensus model.

Hum,
The voyager spacecraft last year felt the shock of a solar storm (Coronal mass ejection). This basically blasted bits of the sun out past the orbit of Pluto.
There is also indirect evidence from meteorite compositions that the early solar system, and various other time periods, that the solar system was sprinkled with heavy elements, from supernovas.

It seems inconceivable that we would not find this material out there.

i think that further tests on the radioactive decompositions in the stardust samples will pin down how much each process actually contributed.

Another, mechanism that has been overlooked is solar-system-size lightning storms (http://www.astronomy.com/asy/default.aspx?c=a&id=2853) (yes, i know, lightening cant happen in space - lets say, plasma storms).

01101001
2006-Mar-14, 05:51 PM
The Planetary Society Weblog: LPSC: Stardust, Monday morning, continued (http://www.planetary.org/blog/article/00000491/)


[Zolensky] reviewed the kinds of mineral grains that Brownlee, Tsou, and Flynn had showed earlier, and mentioned that "the presence of refractory grains" like olivine and pyroxene "is a prediction of the X-wind model" of solar formation. Zolensky was not the only person who mentioned this "X-wind model." I'm afraid I'm not familiar with it but judging by the diagrams they showed it seems to predict that as the solar system formed there were jets of some sort tossing material out from the innermost solar system.
[...]
Zolensky continued by saying "we are not seeing phyllosilicates or carbonates" but that they are seeing some exotic minerals like vanadium-bearing osbornite,
[...]
So, keeping in mind all of the possible sources of contamination, Sandford went on to present some preliminary results. "Carbon is very heterogeneously distributed within individual particles. This is not what I would suspect from a contaminant -- but who knows?"
[...]
In terms of the carbon chemistry, "we see aliphatic hydrocarbons, not as much evidence for aromatic, but then we are not as sensitive to those." He closed by emphasizing "we have yet to verify that the organics are actually of cometary origin, but there are encouraging signs."

Curious, as was Lakdawalla, about the X-Wind model, I found some background in Space.com: Rare Meteorites Linked to Mysterious "X-Wind" (http://www.space.com/scienceastronomy/solarsystem/chondrites_010305.html)


Asteroid bits that fall to Earth may have been born in a hot flash with the Sun, not in the strip between Mars and Jupiter where most of the ancient space rocks currently reside, a new study says.
The finding lends support to a theory that says the solar system formed from the gravitational collapse of a gas and dust disk that created the Sun in a burst of high-impact sculpture while also winging off space objects across vast distances on a blast of energy called the X-wind.
[...]
The astronomical modeling [...] was made public by University of California astronomer Frank Shu in 1996, who proposed an engine for star formation based in part on images from the Hubble Space Telescope showing the creation of new stars from enormous disks of whirling gas and dust.
As a disk contracts, it rotates faster and faster, funneling tons of interstellar dust toward the center, where temperatures reach 3,000 degrees F (1,650 degrees C) or more -- hot enough to melt metal and vaporize most solids.
The rotating disk also produces enormous jets of gas capable of launching debris far into space at speeds of hundreds of miles (kilometers) per second.
Using the Hubble images as a guide, Shu proposed that chondrules in our solar system were created near the hot central disk of the newly emerging Sun rather than in the Asteroid Belt.
According to Shu's theory, dust particles were melted by the Sun, then launched into space by powerful jets of gas and solar wind called the X-wind. While in flight, the molten particles solidified into spherical chondrules, some of which landed in the Asteroid Belt a few days later. Others ended up as the raw materials that formed Earth, Mars and the rest of the planets in our solar system.
"Shu's model provides those kind of temperatures and time scales, and the jets certainly provide a way to kick the grains out to much colder regions of the solar nebula," said Meibom.

VanderL
2006-Mar-14, 09:44 PM
Funny how fast this crazy X-wind model is accepted when the results from the Stardust mission shows us that the dust is exactly what we find in rocky bodies like meteorites and asteroids. Does anyone still think about what makes an apparent rocky object jet? We are repeatedly shown results that are in direct conflict with Whipple's model. Isn't it more important to focus on what a comet actually is, instead of trying to model something more than 4 billion years ago (maybe comets are not that old anyway)? How do we get jets?

Cheers.

01101001
2006-Mar-15, 03:52 AM
Funny how fast this crazy X-wind model is accepted when the results from the Stardust mission shows us that the dust is exactly what we find in rocky bodies like meteorites and asteroids.
Has Stardust shown us only "exactly what we find in rocky bodies like meteorites and asteroids? Or, has some of the cometary material collected been exactly what was expected to come from an icy comet?

And, what makes the X-wind model "crazy"?

VanderL
2006-Mar-15, 06:13 PM
Has Stardust shown us only "exactly what we find in rocky bodies like meteorites and asteroids? Or, has some of the cometary material collected been exactly what was expected to come from an icy comet?

There are many unproven assumptions underlying the "comet model" although it seems there is no one model and it is highly flexible whenever new results are presented. One of those is that comets are formed as icy leftovers from the coldest parts of the solar system.:


"The interesting thing is we are finding these high-temperature minerals in materials from the coldest place in the solar system," said Donald Brownlee, Stardust principal investigator from the University of Washington, Seattle.

Scientists have long thought of comets as cold, billowing clouds of ice, dust and gases formed on the edges of the solar system. But comets may not be so simple or similar. They may prove to be diverse bodies with complex histories. Comet Wild 2 seems to have had a more complex history than thought.

If we remember what was found at Borrelly, Tempel 1 and Wild 2, it seems obvious that ice is only a very minor component of comets. Water production and volatiles are insufficient to explain why comets form jets (plus solar heat seems an unlikely energy source, because jets are produced on the "dark side" as well). If we look at the images we see a pockmarked rocky surface with stark relief, if we look at the dust particles we find rock, if we look at the dust from the Deep Impact mission it is very fine crystalline silicates ("sand").

Looks like rock and it's derivatives/constituents, so why assume that comets form in the coldest regions of the solar system and must contain high amounts of ice? They are very much like meteorites or asteroids in composition. The major difference is that they have jets, a coma and tails. So how do they do this, what makes comets jet?


And, what makes the X-wind model "crazy"?

Bad choice of words on my part, but the model seems to have come from literally nowhere. Did you ever hear about this model before? It is an ad hoc kind of model, and, imo, a desperate one at that.

Cheers.

01101001
2006-Mar-18, 12:06 AM
If we remember what was found at Borrelly, Tempel 1 and Wild 2, it seems obvious that ice is only a very minor component of comets. Water production and volatiles are insufficient to explain why comets form jets (plus solar heat seems an unlikely energy source, because jets are produced on the "dark side" as well).

From 2006 LPSC: BBC: Ice layers record comet creation (http://news.bbc.co.uk/2/hi/science/nature/4816712.stm)

Ice.


Nasa's mission scientists say images from last July's encounter reveal as many as seven different layers on the comet's surface.
[...]
Deep Impact's scientists think the interior structure of Tempel 1 resembles layers of material piled up on one another - a signature of the process that formed the icy body.
[...]
Data from the mission is also helping scientists understand how comets shed water-ice through sublimation, the phenomenon which sees a solid become a gas without first melting.

When comets are heated by the Sun, ice sublimes and is lost to space in a process known as outgassing.
[...]
"I think it is clear from what we have here that the ice that is subliming is within the upper metre. Whether it's 5cm or 20cm below, I wouldn't want to say; but it's not below the top metre. That rules out a lot of the models."

VanderL
2006-Mar-19, 01:28 PM
From 2006 LPSC: BBC: Ice layers record comet creation (http://news.bbc.co.uk/2/hi/science/nature/4816712.stm)

Ice.

Took me some time to get to the real results, and imo there is no substance to the claims. There's only an assumption (layers of "cometesimals" make up a comet) that is not supported by anything but arguments. We don't know that there are "ice layers", we don't even know the amount of ice.


Quote:
Nasa's mission scientists say images from last July's encounter reveal as many as seven different layers on the comet's surface.

They might say this, but based on what?




Deep Impact's scientists think the interior structure of Tempel 1 resembles layers of material piled up on one another - a signature of the process that formed the icy body.

Again, we don't know how icy a comet is, we don't know the layering and again this is what scientists think, but based on what exactly?



Data from the mission is also helping scientists understand how comets shed water-ice through sublimation, the phenomenon which sees a solid become a gas without first melting.

A general remark that is based on the falsified assumption that comets are mainly ice.


When comets are heated by the Sun, ice sublimes and is lost to space in a process known as outgassing.

What we see are jets, and not sublimation.


"I think it is clear from what we have here that the ice that is subliming is within the upper metre. Whether it's 5cm or 20cm below, I wouldn't want to say; but it's not below the top metre. That rules out a lot of the models."

Where did this come from? What is the "what we have here" exactly?
What was observed on the surface is a very small amount of ice, so how does one get jets?

Cheers.

RGClark
2006-Mar-19, 08:48 PM
NASA News Release: NASA's Stardust Findings May Alter View of Comet Formation (http://www.nasa.gov/home/hqnews/2006/mar/HQ_06091_Stardust_update.html)

Anyone know why these high temperature minerals are not simply taken to be the result of impacts?




- Bob Clark