Starship Asterisk*

Hello :D

I attach pictures of a micrometeorite, named Concordia, which comes from the website:
http://www.futura-sciences.com/fr/news/t/astronomie/d/danciennes-cometes-se-cachent-elles-dans-la-ceinture-dasteroides_19964/

I translate a few things, about [b]researches for a possible origin of micrometeorites [/b]:
[quote] From Futura Science: "Indeed, it fells micrometeorites all the time on Earth, which can be easily harvested in the Antartic ices. But they look like a lot to what we know from cometary dusts (we analyzed samples from the cometa Wild II, thanks to the mission Stardust).
Those micrometeorites were mainly likely to proceed from the the asteroids belt, which we think more devoid/lacking of little carbon bodies: we were leading to a defect/anomaly; moreover the isotopic abundances didn't tally.

Nowadays (article published on July 22th 2009), we think (thanks to simulations, following the Nice model, i didn't heard about it) cometas, formed a little further than giant planets, more than 4 billions years ago, would have been ejected towards the current asteroids belt, and thus would have been trapped there (kept here).
According to the dirty snowball of Whipple (yes, i translate the truth!!), comets are less compact than classic/standard asteroids. During collisions with them inside the asteroids belt, it would have been fragmented much more easily. Thus the micrometeorits we receive on Earth would be the remains and pieces of evidence of this pollution of the belt by transneptunian objects (here i guess =micrometeorites)." [/quote]

If you go to wikipedia, there is the definition for transneptunian objects:
[quote]A trans-Neptunian object (TNO; also written transneptunian object) is any minor planet in the Solar System that orbits the Sun at a greater distance on average than Neptune. [/quote]
And, if you go on "minor planet", there is:
[quote]A minor planet is an astronomical object in direct orbit around the Sun that is neither a dominant planet nor a comet. [/quote]
So a micrometeorite can be a transneptunian object.

Have a very nice day!

Céline :)

NYT: From Trees and Grass, Bacteria That Cause Snow and Rain
[url]http://www.nytimes.com/2010/05/25/science/25snow.html[/url]
[quote]
David Sands, a plant pathologist, says the blanket of snow draped over the mountains around town contains a surprise. The cause of most of it, he said, is a living organism, a bacterium, called pseudomonas syringae. ... The accepted precipitation model is that soot, dust and other inert things form the nuclei for raindrops and snowflakes. [/quote]

Hi folks

Found this for you guys.

http://www.cosmosmagazine.com/news/3441/carbon-rich-comet-fragments-found-antarctic-snow

Quote:
'SYDNEY: Two tiny meteorites recently recovered from Antarctic snow contain material dating back to the birth of our Solar System, and may provide clues about the delivery of organic matter to Earth.

Researchers believe that these micrometeorites likely came from the cold, comet-forming outer regions of the gas and dust cloud that comprised the early Solar System, and sample its composition.

Discovered in 2006, the particles measure less than 0.25 mm across and survived their journey through Earth's atmosphere relatively unscathed. More importantly, scientists found that they contain unusually high amounts of organic matter.'

Mark

[quote="wonderboy"]I know a lot of searching goes on in the arctic for meteorites, but would the heat from the space debri not melt its way through the layers of ice covering the arctic meaning they would be quite hard to spot, or would it be cooled enough (since its the arctic) by the time it hits the ice. My thinking is that the friction between the very fast moving rock which is already hot and the cool air would still be enough to keep the rock warm and therfore embed it in the ice. I have no idea how deep, but i would imagine deep enough to make it hard to find.[/quote]
Meteorites are usually very cold when they hit. Their temperature while still in space depends on their composition, but figure that they are about the temperature of a rock in the Sun (since that's basically what they are). When they enter the atmosphere, their outside burns away by ablation. This is very fast, and the ablation carries away heat efficiently. The interior temperature of the stone is hardly affected. The surviving material then spends several minutes falling at ~100 m/s through -40°C air, which rapidly cools it down. Meteorites have been observed to break open when they strike, and the interior frosts up. So any meteorites landing on ice are likely to just lie there.

In fact, the Tagish Lake meteorite in Canada a few years ago did just that. There were thousands of fragments all laying on top of the frozen lake surface. Over a few days, many melted through the ice and fell into the lake simply because they absorbed energy from the Sun and warmed up. If you live in a place with frozen ponds you can easily duplicate this process by tossing a fist-sized black stone out onto the ice. In sunny cold weather it will sink a little every day.

I know a lot of searching goes on in the arctic for meteorites, but would the heat from the space debri not melt its way through the layers of ice covering the arctic meaning they would be quite hard to spot, or would it be cooled enough (since its the arctic) by the time it hits the ice. My thinking is that the friction between the very fast moving rock which is already hot and the cool air would still be enough to keep the rock warm and therfore embed it in the ice. I have no idea how deep, but i would imagine deep enough to make it hard to find.

[quote="Amir"] earth magnetic field[/quote]
I think the magnetic force on the large particles would be much smaller when compared to the gravitationally force, and as a result the magnetic field could be neglected. With that said i think the magnetic field should be considered for iron particles <10microns. This is just my intuition, so a calculation could prove me wrong.

On to the Great news. We got a micrometeorite. I compared the composition of the particle on page 6, to other micrometeorites collected.
[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeYTUzNWRhNDgtMjIzNi00MmQwLWI5MGYtMGZkYTU4ZTJmNWE1&hl=en[/url]

and our particle falls in the micrometeorite composition. It is close to the volcanic composition area but due to the particle size there is no volcano close enough to our collection location.

cheers
Gorkow

[quote="Gorkow"]The samples were very interesting...[/quote]
Indeed. I operated a micrometeorite collection experiment for about 18 months. This consisted of an 8-foot square aluminum collection surface, which drained to a magnet and a set of graded sieves. The entire thing was in a remote mountain location, very far from any industrial sources. We collected a large number of candidate objects (assessed by optical microscopy), both metallic and otherwise, and examined a dozen of the best with SEM/x-ray dispersion spectroscopy. Everything appeared terrestrial. Material fell onto the collector either dry, and was flushed with clean water, or in rain, or in snow. What we collected didn't seem to change much- the deposition rate was fairly constant year round.

thanks a lot Gorkow, for your previous explanations.
the majority of micrometeorites & i guess almost all of the ones you find do have metal in them (Fe,...), so considering earth magnetic field, does it mean that we'd find a huge amount of them in poles? which would also have a greater "real meteorite/volcanic particle" ratio?

The samples were very interesting. The images and compositions are at the following link.
[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeZjNjMTVjMzUtNTMwZi00YjJjLThiNTctNThlMmMyZDhmZjgw&hl=en[/url]

The last two particles are quite interesting,

Page 5- the particle has a whole lot of different elements going on. Visually i would say it is a salt compound. the composition does contain Sodium chloride, and some other non metals, but what is Zirconium doing in the mix, it has a low earth abundance and a low solar abundance.

Page 6- this one is my favorite for being a micrometeorite, though depending on the Mg to SI ratio it maybe a volcanic particle.

The compositions will be compared using there Mg, Si, Fe. ratios to determine if they are micrometeorite. For info on that see the following paper.
[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeY2FhZGY3M2UtNjNjOC00N2ZhLTg5YzAtODI5ZDg4ZjNiYTM4&hl=en[/url]

If you are interested in the abundances of a element just type the element name and then abundance in to Wolfram Alpha, like so Zr Abundance.

cheers
Gorkow

[quote="biddie67"]rain drop's surface tension[/quote]

I think biddie67 is on the right on track with the surface tension of the water. If the incoming particle doesn't have large enough momentum it would bounce off the water droplet instead of breaking into it. This is not the case for snowflakes the particles can get logged into the crevasses of the structure.

[quote="Amir"]don't we have enough regular size Meteorites to study?[/quote]

I am quite thankful that someone asked this question, far to often researchers will become encapsulated in the work (like how to collect only large particles) and lose touch with why the research was important in the first place.

So as to why micrometeorites are important. Well to most people on the street micrometeorites do not affect there life what so ever (but thats the way it goes with most space related research). In taking a step back you can see these little particles are vital to everyone. Space is full of cosmic dust and when to much is collected in one place, they start to build on each other. The collected dust or dust cloud acts as a radiator cooling the center and radiating the thermal energy out. Until the center is around 3 Kelvin, with everything moving slower the gases and the dust particles start sticking together. Coagulation continues on and on, until in the center a sun is formed and the larger dust particles start to orbit. These orbiting particles group together and forming planets, asteroid belts, comets, and such. But not all the particles are collected on these bodies they continue to float around in space. These left over particles slow rain down onto the planets, and we call them micrometeorites. (I tried to make it an simple explanation so i may have miss some steps or made some errors but if you want more info search cosmic dust/early solar system or read the first few chapters of 'the secret life of dust' by hanna holmes.)

So some micrometeorites are reanimates from the early solar system, but they also come down from comets, meteor-showers, (other large interplanetary objects)
The micrometeorites from the larger bodies have compositions similar to the parent body, which is different than the composition of the early cosmic dust. So the solar-dust micrometeorites give more information about the early solar system, when compared to regular size (>1mm) meteorites. Now how do we determine where the meteorites came from (cosmic dust or comets), I don't know of the top of my head but probably by comparing there compositions to regular size meteorites.

There are probably some other reasons for studying micrometeorites but i think i addressed one of the main ones.

Now on to the Good news, this Friday is our appointment with the electron microscope. So will be getting some better images and the elemental compositions of the particles. below are links of the particles we are taking. (note some of the particles on the first link were broken and/or were unable to mount for the microscope)
[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeODUxNTAwMjQtOWYxOS00ZDBmLTgxN2YtY2ExYTRiOWUwMzA1&hl=en[/url]
[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeOTU4MDdhZjMtZDlkMi00ZTkwLWFmYjMtNDY0MmMyNTQ5OTdm&hl=en[/url]

so everyone can look forward to Friday afternoon for a posting of the results.

cheers
Gorkow

Hi,
it's the first time i'm hearing about Micrometeorites.
I'm wondering why they are so important?
don't we have enough regular size Meteorites to study?

What a wonderful learning environment!!! Kudos to both Grokow and RJN!!

I have a question about the effect of a rain drop's surface tension (independent of smaller presenting surface area and higher velocity). Could it possibly repel or vector off in another direction an impacting micrometerite which would also be a factor in collecting fewer micrometerites.

Is there a difference in a snowflake's surface area that could cause a "sticky" factor for collecting micrometeorites that a rain drop doesn't have?

The filter method i described before (using a magnet placing it under a slide), did remove a lot of the smaller particle. The abundance of 20 micron particles decreased by a factor of 4, and the 30 micron particles decreased by a factor of 3/4. see the link for graphs.

[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeYzc4ZGQ4MTMtYTk3Ni00MjdkLWFjYTItMjg4NTc4MWU2ODUx&hl=en[/url]

Some tweaking is need to make the system more selective but that will be set aside for another day. Thou when you think of new filter systems please post them.

Now that we have a diverse selection of particles we'll be making a trip to the electron microscope for imaging and chemical comp. This will be done after spring break so keep you fingers crossed until then, and hopefully we'll have some micrometeorites.

Gorkow

[quote="Gorkow"]
i am now trying to think ways to separate the larger particles (>50microns) so i only collect them.
Gorkow[/quote]
There must be some commercially-available filter out there that can help. Perhaps a fine wire mesh or a vacuum cleaner paper filter. The snow melt might be drained through the filter first and only the large stuff that stuck to the filter would survive. This stuff could then be further filtered for magnetism by dumping it onto a magnet. Those that (again) survive could then be further filtered by shape to ferret out the near-spherical bits.

Since the large particle size already strongly selects for particles that fell nearly straight down (and hence did not blow over from Africa, for example), I would bet a significant fraction of this triple selection process would be actual micrometeorites.

So I was doing some spot sampling on the 8 snow magnets i have, and it turns out that i have a surplus of particles. In other research this maybe good, but not for us. An estimate of the 2 gallons of melted snow has 200-500 particles (of 20microns and higher). You can still uses these if you really need to, but it will take a long time to process. For instants the snow results i posted on Feb 10th had 100 particles and it took me 12hrs to fully process them.

i am now trying to think ways to separate the larger particles (>50microns) so i only collect them. This would greatly decrease the particle counts since the size distribution goes as an exponential. Then we are interested in that range anyways so we don't need the smaller particles.

So if any one has an idea on how to separated the particles, so i only have to look at the larger ones, i am all ears.

Reminder on the setup i have the melted snow dripping from a funnel directly on to the magnet.

The idea i had was using the magnet field to separate the particles. To do this i would place the magnet under a microscope slide, increasing the distance the magnet was from the dripping water. This would then decrease the force from the magnet force acting on the particles as they fell with the water. The idea behind doing this was that larger particles would have a larger magnetic field (this however also depends on the composition). Because the field on the particles would be weaker hopefully only the larger particles would be collected.

[on another note having the particles on top of the slide makes them easier to isolate for the SEM]

I did exactly that Monday using 4 of the larger magnets to trap the particles. Using 4 magnets collected a lot (~300) of the particles including the small ones. Then today i tried using only 1 magnet this however collected hardly any particles. Thus i need to find some happy middle ground, and i think it might work.

please post other ideas

Gorkow

The results of Gorkow indicate that snow is about 20 times as effective as catching micrometeorites than rain, per melted volume. I did not expect that. But that is what science is all about! An atmospheric scientist I spoke with here at MTU said that he WOULD have expected snow to catch more stuff than rain, and was not surprised by the 20x number. He said he was unaware of any publication on the subject, though. But then again there might be -- he just didn't know. So this might be new knowledge, or as said on Saturday Night Live -- just new(s) to me!

A really interesting feature of this is that one can figure out how much snow one needs to catch a micrometeorite and then go out and get it. And the amount of snow would be much less than the amount of rainwater needed. Quite possibly, one could get a daily micrometeorite count by collecting snow (in northern climates) every chance once gets and then melting it, microscope-ing it, and counting the round, melted-looking, magnetic-sticking stuff that measures 50 microns and higher.

It seems to get a real micrometeorite observatory going, though, we need a faster way to tell the micrometeorites from the background gunk. Perhaps placing the size cut at well over 50 microns might work. Even so, if the fraction of micrometeorites to gunk is significant and constant, just counting candidates might itself be useful.

[quote="bystander"] Rain drops, being nearly spherical
[/quote]

I vaguely remembered a presentation on how rain drops are not necessarily spherical. They begin spherical, but change shape as they fall down, due to air resistance. I went back and looked it up, and here is what I found

"Raindrops have sizes ranging from 0.1 millimetres (0.0039 in) to 9 millimetres (0.35 in) mean diameter, above which they tend to break up. Smaller drops are called cloud droplets, and their shape is spherical. As a raindrop increases in size, its shape becomes more oblate, with its largest cross-section facing the oncoming airflow. Large rain drops become increasingly flattened on the bottom, like hamburger buns; very large ones are shaped like parachutes."

I think, that in this particular instance, rain drops "broke up" too much as they fall, thereby "losing" any micro-meteorites that were clinging on to the droplets. Turns out the study of how water droplets coalesce and fall etc, the size, shape, etc is a subject of very high academic and research interest, and my theory is just speculation.

This is pure speculation, but I think both might be related to surface area (SA). Rain drops, being nearly spherical, would have a minimal SA for a given volume (V) or weight (W). A larger SA:V ratio would provide a greater collecting surface and a larger SA:W ratio might allow for a longer descent (and exposure) time.

But that raises another question, is it surface area alone that is the key, or one or both of the previously mentioned ratios. For rain drops, SA:V (and SA:W) varies inversely to the size of the drop (SA/V = 1/3r, and W increases proportionately to V). For snow flakes, I'm not sure how you would calculate SA and V (probably involves fractal geometry), but i assume similar relationships would probably apply. This would imply that the smaller rain drops and snow flakes would collect more particles if the ratios were important, but less particles if just the SA was important.

I don't know how you would measure the relative size of rain drops or snow flakes, but even a subjective estimate might be interesting.

Just a thought.

Well, I have collected some larger snow samples with a slightly altered method than the previous posts. Method 2 involved letting the snow fall in the tub instead of going out and picking up previously fallen snow. This method allows for an accurate time stamp on the samples. The tub is about 80cm wide 30cm long and 12cm tall. Then i did some control samples using distiled water to make sure the tubs were clean.

Now the first sample collected was that of rain, which was unlikely for this location at this time of the year. The rain sample does give us something to compare the later collected snow samples to. Now with the rain i collected 0.5 gallons of water. Then after the rain the very next day it snowed considerably. The snow melted down to 3/4 gallons.

The first interest is in the size distribution, we are looking for particles around 50 microns or larger. Why those sizes? because they either they are from a local source or from space. The second interest is later when the particles are taken to be analysed, to see if there are any micrometeorites.

So i recorded the sizes of all the particles from the rain and snow (graphed on the links). There are two major items to point out, one snow collects more particles than rain, the other is snow collects more larger particles.

[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeYWRmNjBmMzAtMjc1MC00NzRhLWExMmItMTM0NWQzODczM2M0&hl=en[/url]
[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeOTVkOTE4YTktYmU4Yi00OWNhLTkxODUtM2UzY2MwNzg5ZTY5&hl=en[/url]

There are 10 more snow samples to look at, so i got some work to do.

But here are some questions i would like your input on.

Why is it snow collects considerably more particles than rain? Is it due to the size, or the longer flight time, or any number of other factors.

Why does snow collect more larger particles? is it the size too or something else.

feel free to raise other questions for discussion.

Gorkow

I have found out that studying how rain and snow collect stuff in the atmosphere is actually an active topic of meteorological research. This is not uncommon for me -- many times a key to progress has been the connection to an already established field. And one way to do that is to know the right keywords that are used in that field. So after a brief conversation yesterday with an atmospheric physicist, I learned some good keywords! These include "scavenging" and "deposition." Knowing this I was able to search better on the web and find several articles. Also, here is a useful Wikipedia entry: http://en.wikipedia.org/wiki/Deposition_%28Aerosol_physics%29

It turns out that there are at several kinds of established scavenging:

precipitation scavenging: from rain
snow scavenging: from snow
cloud scavenging: in clouds

From my preliminary readings, it seems that most current scavenging techniques primarily focus on finding and analyzing aerosol particles much smaller than about 50 microns, the smallest size which we have been searching for micrometeorites. Still, I may be mistaken, and in any event I will continue to read and try to understand.

Gorkow,
Thanks for the answer.

In any case, have you thought of using a high power electrical magnetic field to look for copper in the micro meteorites?
Copper can only pass through a magnetic field slowly and thus you could separate them from other particles.
Just an idea for your experiment to be carried a bit farther in it's investigations of micro meteorites.
How many of the meteorites contain copper? What percentage?

Houghton is now covered in snow, so here are the results from 3 snow samples.

You can find and explanation and pictures of the collection method at this link
[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeNTg1ZDNkZTQtMmU2ZS00MWRlLWJmOTMtNTRlYTJmMGNiMWMy&hl=en[/url]

Now these samples were collected from a semi-continuous snowstorm that lasted 3 days (12/4 to 12/6). The snow samples were all the same volume (1.5gal or 6 L), so if the snowflakes where forming around these particles the samples should collect roughly the same amount of particles. The total particles collected for each sample are listed below, and are graphed on the link.
[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeZmYzNmNiYTktZDRiZS00NzUwLThlNjktODEwODM2ZjljMjFj&hl=en[/url]

12/4/09-----66 particles
12/5/09-----37 particles
12/6/09-----12 particles

So I think the decrease in the particle count means that snowflakes do not usually formed on the particles but the particles are collected on the snowflake as it falls.

Now on to what kind of particles I found. The following link is to the more interesting particles I found. The first 4 particles I classified as candidate micrometeorites.
[url]https://docs.google.com/fileview?id=0B7C_X6Yg7LHeZDBkZTM2NDItZmM5OS00Y2M2LWFiMmYtMDY4MDhjYTljYzQw&hl=en[/url]

Then an answer to the following question asked
[quote="craterchains"]So, from this I take it you are only looking for micro meteorites that can only be attracted to a magnet?
What about all the others that are nonmagnetic?[/quote]
The answer is most meteorites contain iron-nikel metal, so micrometeorites would also contain these elements thus they would attach to the magnet. Note there are rare meteorites that contain no magnetic elements, but those are harder to find.

Gorkow

Been away a few days...but judging by the new "Code" button
I guess that you figured this out for yourself.

"Code" is useful for tables and the like.

[quote="RJN"]Neufer,
What code did you use?[/quote]
[code]Been away a few days...but judging by the new "Code" button
I guess that you figured this out for yourself.

"Code" is useful for tables and the like.[/code]

So, from this I take it you are only looking for micro meteorites that can only be attracted to a magnet?
What about all the others that are nonmagnetic?

Neufer,
What code did you use?