Hayabusa 2 on its way back to earth

[lajoswinkler]

On 10/3/2018 at 7:24 AM, cubinator said:

There's rocks of all sizes there, I'm sure, including lots of those tiny dust particles you don't want to breathe in.

Just the other day I was thinking of how carbonaceous chondrites are almost certainly carcinogenic. Billions of years of exposure to harsh UV in vacuum, sooty crap all over...

[KG3]

2 hours ago, lajoswinkler said:

Just the other day I was thinking of how carbonaceous chondrites are almost certainly carcinogenic. Billions of years of exposure to harsh UV in vacuum, sooty crap all over...

Polycyclic aromatic hydrocarbons, mmmm bacon.  My favorite carcinogen.

[lajoswinkler]

4 hours ago, KG3 said:

Polycyclic aromatic hydrocarbons, mmmm bacon.  My favorite carcinogen.

At least bacon is tasty. Ryugu probably tastes like ash.

[insert_name]

gif of mascot descending

http://www.hayabusa2.jaxa.jp/en/topics/20181005e_MSC_ONC/

[insert_name]

Summary of mascots now completed mission

https://spaceflightnow.com/2018/10/05/mascot-lander-hops-around-asteroid-exceeding-scientists-expectations/

[insert_name]

touchdown rehearsal today, actual thing delayed to next year

http://www.hayabusa2.jaxa.jp/en/topics/20181014e_TD/

[insert_name]

3rd touchdown rehearsal underway

http://www.hayabusa2.jaxa.jp/en/topics/20181024e_TD1-R3_Schedule/

[insert_name]

video of candidate landing zone from the third touchdown rehersal

http://www.hayabusa2.jaxa.jp/en/topics/20181026e_TD1R1A_W1movie/

[KG3]

How are rocks from Ryugu classified geologically?   I'm assuming that the reason they are so interesting is that they haven't changed much over the eons but that also means that they are not on the familiar rock cycle of igneous, sedimentary, metamorphic that we find here on earth.     

[insert_name]

Gravity map of ryugu has been produced

http://www.hayabusa2.jaxa.jp/en/topics/20181225e_AstroDynamics/

[Green Baron]

On 10/29/2018 at 12:57 PM, KG3 said:

How are rocks from Ryugu classified geologically?   I'm assuming that the reason they are so interesting is that they haven't changed much over the eons but that also means that they are not on the familiar rock cycle of igneous, sedimentary, metamorphic that we find here on earth.     

True, the processes that form the rocks on earth and possibly other planets do not exist on asteroids. Roids can be classified by the spectrum (spectral classification), which depends on the type and composition of the surface material.

But as the earth is in principle formed from the same stuff, it is no surprise that we find minerals there that closely resemble those from the earth's mantle (olivine, pyroxene) and core (iron, nickel), as well as crust (silicates), in different parts on different types of asteroids. And of course carbon, hydrogen, oxygen ...

Edited January 7, 2019 by Green Baron

[kerbiloid]

Maybe that depends on the planetoroid origin.

If it's a part of a core of something bigger, melted and so on, probably it's igneous or metamorphic or so.
If it's a ball of stuck dust, probably it's sedimentary.

I bet on this.

[Green Baron]

I wouldn't :-)

Seriously, metamorphic rocks are heat/pressure transformed sediments and volcanic rocks. The were brought down into the crust (or a little below) by subsidence or in subduction zones, and subsequently uplifted again for example in an orogeny (forming of mountain ranges) and then start to weather out. The "metamorphic facies" describe the conditions and outcome of rock metamorphosis, depending on the original material. These processes are impossible to replicate on asteroids, they lack the necessary temperatures and pressures and collisions are too short for the minerals to form (though we find on earth shock transformed minerals that resemble those from meteorites (and thus probably asteroids as well). Metamorphic rocks rarely contain many organic compounds, unlike some asteroid surfaces.

Sediments are weathering and erosion products that form out of volcanic or metamorphic material through physical and chemical processes. Water, wind, ice, atmospheric chemistry, gravity play a role and in a much greater scale crustal processes like uplifting. No uplift -> (almost) no erosion, otoh subsidence -> deposition. You won't find these things on asteroids, maybe superficial different "weathering" products that formed through billions of years of particle bombardment and radiation exposure.

 

Edited January 7, 2019 by Green Baron

[KG3]

16 hours ago, Green Baron said:

 You won't find these things on asteroids, maybe superficial different "weathering" products that formed through billions of years of particle bombardment and radiation exposure.

 

Interesting.  Each asteroid has a history though.  Depending on how far from the sun it formed, or if it was part of a larger body, or if it collided with other stuff, etc... I wonder if we might ever find a rock sitting on the surface of an asteroid that was blasted off the surface of the Earth from early in our history.    

[kerbiloid]

18 hours ago, Green Baron said:

Seriously, metamorphic rocks are heat/pressure transformed sediments and volcanic rocks. The were brought down into the crust (or a little below) by subsidence or in subduction zones, and subsequently uplifted again for example in an orogeny (forming of mountain ranges) and then start to weather out. The "metamorphic facies" describe the conditions and outcome of rock metamorphosis, depending on the original material. These processes are impossible to replicate on asteroids, they lack the necessary temperatures and pressures and collisions are too short for the minerals to form (though we find on earth shock transformed minerals that resemble those from meteorites (and thus probably asteroids as well). Metamorphic rocks rarely contain many organic compounds, unlike some asteroid surfaces.

If an asteroid rock is a piece of this from a broken protoplanet, it stops being metamorphic?

18 hours ago, Green Baron said:

Sediments are weathering and erosion products

As I can understand, sediments are products of a dust or garbage settling just by name, not specifically carried by water or wind.

[YNM]

5 minutes ago, kerbiloid said:

sediments are products of a dust or garbage settling just by name, not specifically carried by water or wind.

By this standard all accretions are sediments.

[kerbiloid]

So, we need a specialist's opinion.

[Green Baron]

4 hours ago, kerbiloid said:

If an asteroid rock is a piece of this from a broken protoplanet, it stops being metamorphic?

That is hypothetical. What is a protoplanet ? Is it already differentiated ? Where does the piece come from ? Has it undergone changes from the original material, how long was it exposed, has it undergone other changes in the meantime (high pressure modifications have a limited stability, if pressure is released). The question works better the other way round: if a piece is found (example: meteorites from Mars), we can tell with some confidence that it was a basalt, it formed under that temperature and that pressure (facies) and has traveled around for quite some time. So we know from what depth on Mars it came from.

Quote

As I can understand, sediments are products of a dust or garbage settling just by name, not specifically carried by water or wind.

Besides weathering processes, means, medium and distance of transport are the very base of sediment definition and classification. Grain size, chemistry, minerals largely depend on that. If it is preserved well, one can tell where it came from, how it was transported and the regime it was deposited in. Did it flow, was it blown, was it transported by ice ? Constantly or periodically ? How far was it transported ? How high was the energy ? Was it cold or warm ? Which minerals weathered out ? etc. pp.

I must add: sediment geology is complicated. I mean complicated. :-) And there many different subjects with different view points for a given case, like oil industry, paleontology, construction works, they all have different questions. But none are adoptable to asteroids, comets and the likes.

It would be best to avoid these concepts when speaking about small celestial objects.

 

Edit: Back to Ryugu: once the samples are back on earth i am sure we "will have some very nice data here" to analyse.

 

Edited January 8, 2019 by Green Baron

[YNM]

4 hours ago, kerbiloid said:

So, we need a specialist's opinion.

This is why they usually examine the samples based off element abundance and mineral types that's found microscopically as they have a higher chance to pinpoint their origin. Using the classification that geologist use on Earth is rather useless unless the rock was flung off the Earth in some way.

24 minutes ago, Green Baron said:

there many different subjects with different view points for a given case, like oil industry, paleontology, construction works, they all have different questions. 

True, geotechnics only care about it's strength and behaviour with water (seepage and swell), as well as whether further organic decomposition occurs or not. Vast majority of the methods, tables, and equations used are empirical rather than theoretical.

[kerbiloid]

1 hour ago, Green Baron said:

That is hypothetical. What is a protoplanet ? Is it already differentiated ?

Has an iron asteroid appeared from a rust dust?
Afaik, yes, some protoplanets (or planetesimals if you want) are considered differentiated.

1 hour ago, Green Baron said:

was it transported by ice ?

In an icy asteroid? I guess, yes, they were being transported with ice from the very beginning, because they were dirty flakes.
Though, I would prefer to know a specialist's opinion about exact definitions.

1 hour ago, Green Baron said:

It would be best to avoid these concepts when speaking about small celestial objects.

Following your method: how do you define "small" objects?

53 minutes ago, YNM said:

Using the classification that geologist use on Earth is rather useless unless the rock was flung off the Earth in some way.

They do this with Mars. Why shouldn't with 'roids?

[Green Baron]

27 minutes ago, kerbiloid said:

Has an iron asteroid appeared from a rust dust?
Afaik, yes, some protoplanets (or planetesimals if you want) are considered differentiated.

Planetesimals are much too small for differentiation. Something the size of Vesta is needed for it to start (gravitationally). "Protoplanets" are not official and you may have a different opinion than i, so let's say "dwarf planets".

Quote

In an icy asteroid? I guess, yes, they were being transported with ice from the very beginning, because they were dirty flakes.
Though, I would prefer to know a specialist's opinion about exact definitions.

We are talking different things: "transport" of sediments means glaciers and ice shields, ice shelves on oceans, not small snowballs or "graupel". These latter are stable over billions of years, there is no such transport. "Regolith" may be a better word for this, than "sediments".

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Following your method: how do you define "small" objects?

It is not mine. Dwarf planets, comets, planets.

Quote

They do this with Mars. Why shouldn't with 'roids?

I think you can answer the question yourself. Features on Mars may be a hint that in its early years there were sedimentary processes similar to those on earth (flowing water, thick atmosphere). No such things (fluviatile valleys and incises, thick sheeted silicate layers, ...) exist on objects like Ryugu. There may of course be a gray or transition zone somewhere above Vesta size objects that can "afford" an atmosphere and some evolution processes, flowing water and certain forms of circulations between the spheres.

Future will show ;-)

Edited January 8, 2019 by Green Baron

[kerbiloid]

1 minute ago, Green Baron said:

Planetesimals are much too small for differentiation. Something the size of Vesta is needed for it to start (gravitationally). "Protoplanets" are not official and you may have a different opinion than i, so let's say "dwarf planets".

No problem about the name. Any differentiated rocky ball which has been crashed and spread around core and mantle fragments.

3 minutes ago, Green Baron said:

We are talking different things: "transport" of sediments means glaciers and ice shields, ice shelves on oceans, not small snowballs or "graupel". These latter are stable over billions of years, there is no such transport. "Regolith" are a better word for this, than "sediments".

Afaik, "regolith" describes the state, not the origin. 1 m below there is the same rock, and it is not called "regolith", but it definitely has an origin.

4 minutes ago, Green Baron said:

It is not mine. Dwarf planets, comets, planets.

In this context we do not refer to the celestial body classification, but to the size enough "small" to treat it as a treshold of the stones classification applicability,

6 minutes ago, Green Baron said:

I think you can answer the question yourself. Features on Mars may be a hint that in its early years there were sedimentary processes similar to those on earth (flowing water, thick atmosphere).

Io? Europa? Vesta? Others? Which are enough big?

[MinimumSky5]

AFAIK, there is no term for the material on asteroids like Ryugu, which is a significant oversight, IMHO. I'd introduce a new term, something like "Primordial", to demonstrate that the material has not been altered by geological processes in any way.

[YNM]

47 minutes ago, kerbiloid said:

They do this with Mars. Why shouldn't with 'roids?

We have better data on Mars (I think we found like a whole landslide or something from comparison of previous and latter images). If we found them on other bodies, or whatever we found on them, then we'll use it as well, or maybe even use an entirely different classification yet again.

Just now, MinimumSky5 said:

I'd introduce a new term, something like "Primordial", to demonstrate that the material has not been altered by geological processes in any way.

Except we're not sure whether it's entirely pristine until all the data has been processed.

[kerbiloid]

4 minutes ago, YNM said:

We have better data on Mars (I think we found like a whole landslide or something from comparison of previous and latter images). If we found them on other bodies, or whatever we found on them, then we'll use it as well, or maybe even use an entirely different classification yet again.

Probably it will be extended. But "entirely different"...