For Questions That Don't Merit Their Own Thread

[kerbiloid]

1 minute ago, DDE said:

Could be simple gaseous storage. Could be something else entirely.

There is a gothic caption on them.

[DDE]

2 minutes ago, kerbiloid said:

There is a gothic caption on them.

Oh, that I do know.

Ironically, those guys actually hated Gothic fonts.

[kerbiloid]

4 minutes ago, DDE said:

Ironically, those guys actually hated Gothic fonts.

Originally they loved, but later found it too trolling.

P.S.
Probably, this is a false caption to fool a potential saboteur.

Edited March 6, 2019 by kerbiloid

[ARS]

Why biplanes have lower stall speed compared to monoplane/ jets? How they can make tighter turn compared to them?

[StrandedonEarth]

55 minutes ago, DDE said:

Could be simple gaseous storage. Could be something else entirely.

"I want to make a flying tank!"

"Hah! when pigs fly!"

"Any other objections?"

[p1t1o]

1 hour ago, ARS said:

Why biplanes have lower stall speed compared to monoplane/ jets? How they can make tighter turn compared to them?

Thats actually a complicated question that needs to take into account a great many things that are different between a modern fighter.

eg: At low speeds (Im taking a Sopwith Camel as my example, top speed ~110mph) a "high aspect ratio" wing is best (long, stright and narrow) which naturally have excellent stall/AoA characteristics, but at higher speed exhibit much worse drag than other planforms.

But very simply put, a biplane (or aircraft of similar ilk) has a low stall speed and high manouverability mainly because they are made of wire and fabric (fully fuelled masses in the region of 5-800kg, pilot can make >10% of aircraft mass!), thrust-to-weight ratio can indeed rival modern aircraft (although perhaps not so much with VERY modern jets which just have ridiculous engines! Also advances in composite materials that drop mass)

 

Edited March 6, 2019 by p1t1o

[kerbiloid]

Because they are folded sailplanes.

[ARS]

If we planned to mine celestial bodies (don't ask how) in our solar system (that includes moons and asteroids), ignoring the space travel limitations and energy requirements, what's the potential resources that can be gained from each planets (and moons)?

Edited March 10, 2019 by ARS

[Green Baron]

There is only a general answer to this question, as the exact composition of these bodies and their structure is not well known. We have only looked at or scratched the surface. Potentially one could obtain the elements they contain, weighing cost against effort.

Edited March 10, 2019 by Green Baron

[kerbiloid]

If the energy limitations can be ignored (so, we have an unlimited source of power), then obviously hydrocarbons don't make sense.
Because in this case we don't need hydrocarbons as fuel.
As well, no other compound of lightweight elements like ammonia or so. We can just produce them anywhhere or avoid using.

Unlikely one needs to mine helium-3 on the Moon, as it's too rare, and it's easier to produce it, say, from the oceanic lithium.

Once we can use pure deuterium in a fusion reactor (as they did it in a thermonuke explosive device), we have than deuterium almost everywhere except maybe Mercury. So, no need to import/export it.
Until that, it's mostly useless in large amounts.

So, we can mine water/hydrocarbon/ammonia just for local needs (which would be mostly limited with fuel production) and to create emergency deposits of storable compounds just in case.  (Say, to repair the Earth after an asteroid hit)

So, probably only metals make sense as imported goods. 
This makes outer planets mostly useless in this sense. Icy moons, moons covered with thick layer of ice, gas giants. 

But we have a lot of aluminium and iron on almost any rocky body. So, if have a lot of energy, there is no sense in delivering them from somewhere, it's much easier to mine or recycle them locally.
More or less the same with magnesium, titanium, and silicon.

Other metals on the Earth are usually associated with hydrothermal deposits and sediments
Either a flow of hot water from below washes salts from the rock and brings them to the surface. Water dissipates, metals stay as a spot. Then we mine it. Afaik, lead, silver, copper, tin usually have this origin.
Or something gets washed out water, then either floats in ocean like lithium and uranium, or sinks and becomes a spot on the sea bottom. When the sea dries, it gets being on land, and we mine it.

So, active geology and great amounts of time and water mean very much for the planetary resources availability.
Unlikely we can expect this on Mercury (too hot, too small). Even if it's rich with metals, probably they stay scattered and deeply buried.

 

Venus definitely had a lot of water evaporated from the rocks.
(It has a thick atmosphere of CO2, which is a former vulcanic gas. Another part of this gas is the water steam. So, we can assume that a whole ocean of water has passed from the rocks into the air, and then has partially dissipated into space, partially splitted by UV and also dissipated.)

But Venus doesn't have a heavy moon.
Also, it rotates slowly and in opposite (i.e. original) direction, it's equator is not tilted (3°). So, it never had a heavy moon.
Expectedly, it doesn't have continental platforms (only tiled surface structures, so its crust is formed as a result of cooling, not of continental drift), and its core is dead, it doesn't have a magnetosphere.
Also, this means that it probably never had an ocean, or at least it was not lasting too long.
So, unlikely we can expect a lot of hydrothermal or sedimentary metal deposits, just common elements, as everywhere.
Without Moon as kickstarter, Venus is a dead failed Earth, covered with useless unpleasant gas layer. It probably has same treasures as Earth, but they are scattered inside the planet.

 

Moon is a piece of slag. Nothing special here, but it can be mined for titanium, maybe nickel. Just because Moon is close, titanium is good.

 

Mars definitely had an ocean, and it probably was hit by something of Pluto size. (One of its hemispheres is probably an impact crater).
Looks like it has sedimentary minerals formed in a lake or river.
But it's small, and was not lasting long. So, unlikely Mars can have anything comparable to the terrestrial ore deposits. So, nothing to mine for import.

 

Asteroid belt is very tiny. Its total mass is just 4% of the Moon mass, and several largest of them containt most part of that.
As the largest ones are ~300..1000 km in size, most part of that most part is deeply buried just like on the Moon surface, so in fact the asteroid mass available for mining is comparable to the Moon mines, and contains nothing more precious than same common elements.

Some meteorites contain high concentration of platinoids, so probably there are asterioids containing them as well.
But:
1) they are too small to mine a lot of scattered platinoids at once;
2) they scattered in orbits to just move from one to another for mining.
3) most of them don't have anything useful (like the Earth meteorites as well), at least to keep catching every piece of rock around the Sun.

So, unless the astronomers find a shining platinum ingot orbiting around the Sun, unlikely asteroid belt can provide something enough significant to be mined.

***

So, probably, the only real thing to mine is solar energy. And it creates a positive loopback allowing other mining to have sense.

As I can see/am sure, there is a bunch of four ways of the Solar System further utilization.

1) Building, sending, and supporting a large fleet of telescopes to know every stone in Solar System, and to study closest stars to prepare the interstellar travels.
This can require orbital facilities near some of gas giants and probably mining of its ice and hydrocarbonic moons, to locally fuel the boosters.
Mining local ice to extract deuterium for local fusion reactors.

2a) Creation of the mentioned extraterrestrial emergency resource deposits.
Just building automated plants which will lazily and meditatively keep extracting common metals from trash rocks and store them as ingots; and gathering hydrocarbons and nytrogen and storing this as plastic bricks.
Just to quickly take as much as needed if something bad happens, to restore the civilization on Earth.
Mining local ice to extract deuterium for local fusion reactors.

2b) Preparing extraterrestrial asteroid-sized vault(s). 
A decentralized data storage keeping virtual copies the culture artifacts, DNA codes, so on. Also a shelter for the personnel which will be restoring Earth if something happens.
For obvious reasons, probably it's combined with 2a 2-in-1.

3) Building the inverted Dyson sphere.
All of above require a lot of energy, as well as many other things do.
We do not a horrible artificial cave around the Solar System to utilize the Sun energy.
We need a enormous fleet of collectors/reflectors/emitters orbiting in low-Sun orbit, and focusing the Sun light in desired directions. To power the listed above, for Earth needs, to power interplanetary and partially the interstellar ships. Ideally, no photon should escape a light collector. Everyone should be captured and re-emitted.

The near-sun swarm of collectors-emitters requires a lot of metals to be built, but at the same time provides a lot of energy to extract them. A positive loopback, boosting the process of the Solar System utilization.
And these are the common trash metals: iron, aluminium, etc.

So, I guess, first Phobos and Deimos should be totally disassembled to build first wave of the solar collectors-emitters.
Then the asteroid belt. This in turn, means that all those famous platinoids from asteroids are extracted and collected as a by-product, and delivered to the Earth and the vaults.

Every time the swarm power grows, and the mining gets faster and faster.
In its time the useless Mercury should follow the asteroids.

At some point the Solar System becomes a darker place, where the solar light is partially directed in various places.
The Sun visible surface will be visually covered with grid of the emitters swarm.

No asteroid belt, except several orbital vaults invisible from distance.
Just a remain of Mercury still not disassembled, but soon.

Mars and Callisto covered with endless containers of metal and plastic bricks.

No more many small icy moons of Jupiter and others. Spent as fuel and collected as plastic.

Venus is probably heated with the solar swarm, its atmosphere swells, and CO2 keeps being collected in orbit and turned into plastic together with former icy moons and asteroids.
In its time its greenhouse effect passes, Venus becomes just a rocky planet with no water and air. Then it will be turned into the largest vault, maybe even partially terraformed, thanks to its gravity.

So, I guess absolutely nothing as romantic as Expanse is.

[Gargamel]

14 hours ago, ARS said:

If we planned to mine celestial bodies (don't ask how) in our solar system (that includes moons and asteroids), ignoring the space travel limitations and energy requirements, what's the potential resources that can be gained from each planets (and moons)?

I used to work a lot in production of products that used a lot of Iridium and Ruthenium.   A good portion of today's technology, from chemical production to electronics, comes from processes that use these elements.   Last I checked, we only mine a couple tons of new material of these elements every year, and then it's just a by product of other mining operations.  Mainly because these elements are only found in high enough concentrations to mine in the layer dust layers laid down from major asteroid impacts. 

Even being able to get a single ton of these elements from an orbiting asteroid would have a great affect on the markets for them. 

[p1t1o]

On 3/10/2019 at 1:04 AM, ARS said:

If we planned to mine celestial bodies (don't ask how) in our solar system (that includes moons and asteroids), ignoring the space travel limitations and energy requirements, what's the potential resources that can be gained from each planets (and moons)?

Imagine an alien asking "What resources can be extracted from Earth?" and how long it would take you to answer and what the answer depends on.

[DDE]

On 3/10/2019 at 4:04 AM, ARS said:

ignoring the space travel limitations and energy requirements, what's the potential resources that can be gained from each planets (and moons)?

Nothing. Welcome to the fun world of synthesizing arbitrary elements.

[kerbiloid]

2 hours ago, p1t1o said:

Imagine an alien asking "What resources can be extracted from Earth?" and how long it would take you to answer and what the answer depends on.

Land here.

Edited March 11, 2019 by kerbiloid

[CastleKSide]

Bouncing off of the question of space mining, here is a question I have been speculating on for some time:

Given most of the things we want to mine are heavy/dense (metals) is it a reasonable assumption they would be in higher concentrations in the cores of differentiated bodies? I think so, which leads to the next part. What technological level would you need to be able to mine from the core of the moon? How deep could we reasonably attempt to mine on the moon with current technology? What's the largest differentiated body in the Solar system we could mine the core of? (ignore the probable profitability of such ventures, just looking at could we do it)

[kerbiloid]

42 minutes ago, CastleKSide said:

Given most of the things we want to mine are heavy/dense (metals) is it a reasonable assumption they would be in higher concentrations in the cores of differentiated bodies?

Not necessary.
https://en.wikipedia.org/wiki/Goldschmidt_classification
Uranium is heavy, but it's lithophile, so you don't need the core to mine it.

42 minutes ago, CastleKSide said:

What technological level would you need to be able to mine from the core of the moon?

As we calculated somewhere above, you need to get through 10¹⁴ times greater amount of matter to reach the Earth core than to reach Proxima.

So, the required level is Planet Killer.

42 minutes ago, CastleKSide said:

How deep could we reasonably attempt to mine on the moon with current technology?

Several meters. With a nuke - several hundred.

42 minutes ago, CastleKSide said:

What's the largest differentiated body in the Solar system we could mine the core of?

Jupiter.

Of rocky ones - probably Earth, as we have been happily forced to melt inside when the proto-Moon had arrived.

To reach the core: any metal asteroid, and only them.
The differentiation starts for the bodies of hundreds kilometer size, so the core would always be under tens kilometers of crust, unless the planet is crashed.
So, iron asteroids as crash debris are the core pieces themselves.

As you can see from the table, the goldenoids are siderophiles, so they concentrate in the core.
That's why they hope to mine the metal asteroids for platinum.

Edited March 13, 2019 by kerbiloid

[DDE]

4 hours ago, CastleKSide said:

Bouncing off of the question of space mining, here is a question I have been speculating on for some time:

Given most of the things we want to mine are heavy/dense (metals) is it a reasonable assumption they would be in higher concentrations in the cores of differentiated bodies? I think so, which leads to the next part. What technological level would you need to be able to mine from the core of the moon? How deep could we reasonably attempt to mine on the moon with current technology? What's the largest differentiated body in the Solar system we could mine the core of? (ignore the probable profitability of such ventures, just looking at could we do it)

16 Psyche is an exposed protoplanet core, and some describe Mercury as one.

[Green Baron]

5 hours ago, CastleKSide said:

 What technological level would you need to be able to mine from the core of the moon?

The moon is mostly basaltic, it is assumed to only have small solid iron core of <200 km diameter. No tech can dig that deep. On earth we get to 12km, there where the crust is thick and cool. And you need gravity to keep the borer straight and pointing down. On the moon, a borer will likely divert. But we can't take the necessary mass there anyway.

Quote

How deep could we reasonably attempt to mine on the moon with current technology?

We can't. We don't have the tech to schlepp heavy industry to the moon.

With the stuff that fits in a lander i say 10m. A small borer on Mars just got stuck at a few decimeters because it struck a hard rock or so. Bad luck. But one also needs to take stuff out, (pre-)process it, get it away. This is impossible at the current level.

Quote

What's the largest differentiated body in the Solar system we could mine the core of? (ignore the probable profitability of such ventures, just looking at could we do it)

We can't mine the core of any large asteroid. We can get there and take pictures, analyze gases and if equipped to do so small particles with built in telemetry or sample collection. Maybe we can bring surface samples in the mid future (20, 30 years), like we did with comets. But that'll be a multi-decadal task to plan, build and carry through, to bring a few kgs of something.

For Psyche, several hypotheses are in discussion for its composition, an exposed core of a differentiated asteroid or dwarf planet being one of them. Mercury is a fully differentiated planet with a density slight less than earth's. As it lacks gravitational compression due to its smaller size, its ratio core/mantle volume is higher than earth's. A collision that stripped of a part of its crust and upper mantle after differentiation could hypothetically explain this if we assume that Mercury formed in the same processes as earth and thus should have the same ratio. But Mercury is not an exposed core.

Edited March 13, 2019 by Green Baron

[DDE]

1 hour ago, Green Baron said:

Maybe we can bring surface samples in the mid future (20, 30 years)

Japan would like a word.

[kerbiloid]

Psyche's density is ~3700 kg/m3, i.e. almost equal to the Moon density, or to the terrestrial crust.

As iron is 7800 kg/m3 dense, and the planet cores may be almost twice denser, it looks like the Psyche's core'ity is overestimated.

[Green Baron]

Attention when using mere density, calculated for low g conditions, for comparisons: The moon as a much larger body than Psyche, mostly basalt that would have a density of ~3 on earth's surface, has a mean density of 3.3 due to gravitational compression. But it is mostly basalt (but see below earth). Psyche's density is inferred from other M-types and may just be wrong, as other values are published as well (like 4.6 +/-). Psyche's albedo hints to a metallic surface, so there is a slight contradiction.

 

Earth's crustal density is considerably lower than that: 3-3.3 oceanic, 2.7 continental. This is a difference, huge enough to drive plate tectonics. Earth's mean density, otoh, is much higher due to its iron/nickel core and more so gravitational compression.

Also, earth's density from pure calculations should be a little higher than it is, there must be around 6% lighter elements in the core, like sulphur and maybe silica stuff.

33 minutes ago, DDE said:

Japan would like a word.

With whom and because of what ? If you cite me then do so completely "like we did with comets"

You know, asteroids and comets are different. In all respects. Like gravity. Landing. Leaving.

Edited March 13, 2019 by Green Baron

[DDE]

36 minutes ago, Green Baron said:

With whom and because of what ? If you cite me then do so completely "like we did with comets"

You know, asteroids and comets are different. In all respects. Like gravity. Landing. Leaving.

Well, they returned the samples in 2010, and are acquiring another set.

And no, the dichotomy between asteroids and comets is getting shot full of holes, such as centaurs and main-belt objects with cometary charecteristics.

[kerbiloid]

1 hour ago, Green Baron said:

Psyche's density is inferred from other M-types and may just be wrong, as other values are published as well (like 4.6 +/-)

4.6 is still twice less than iron.

Probably, just a piece of rock with scattered fragments of core on surface.

I guess, just an underdeveloped thing. The differentiation had started, but the mass was too low. So, just a partially extracted iron, not a hall of mountain king.

Edited March 13, 2019 by kerbiloid

[Green Baron]

3 hours ago, DDE said:

Well, they returned the samples in 2010, and are acquiring another set.

And no, the dichotomy between asteroids and comets is getting shot full of holes, such as centaurs and main-belt objects with cometary charecteristics.

IKR ! And in 2023 when and if Osirix Rex returns a sample of a few decigrams from Bennu we'll know some more.

And if you cite me, do so correctly.

2 hours ago, kerbiloid said:

4.6 is still twice less than iron.

Pls. doublecheck that. 4.6 * 2 is 9.2 on my calculator, not 7.8 ?

These density differences may be too small to mention in a pie recipe, but they actually do matter in astronomical scales, like differentiation if bodies and motors of crustal movements.

Quote

Probably, just a piece of rock with scattered fragments of core on surface.

If you say so :-)

 

Edited March 13, 2019 by Green Baron

[kerbiloid]

5 hours ago, Green Baron said:

Pls. doublecheck that. 4.6 * 2 is 9.2 on my calculator, not 7.8 ?

Wow! It's just 1.7 times less not 2.0! This is a gamechanging difference!
And it's only from your words 4.6, the wiki says 3.7 (i.e. 2.1 times less dense that iron), I don't know where did you take that 4.6 from.

Psyche is much less dense than Earth, Venus, and Mercury.
It is as dense as Mars. So, it cannot be a bare core of protoplanet, it is just a piece of protoplanet with partially differentiated metal.
Because its density doesn not differ from the density of a whole planet at that distance from Sun. So, all its rock wastes stay there.