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Skyler4856
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A few questions-

1. What is the likelihood that an external nuclear weapon being carried by a tactical aircraft (like the B61 on an F-16 or the 8U69 on a Su-7B) would detonate upon the aircraft being shot down (by damage/hits that do not completely destroy the engine/power supply, but instead aerodynamic surfaces, like a wing)?

2. Do derelict satellites remain stabilized? Last summer, I observed what appeared to be a satellite transiting the Moon through my telescope, and I wonder whether it was junk or active. It did not appear to be tumbling.

3. What do spacecraft smell like inside? Is scenting used ("that new Soyuz smell"), or is maintaining a "neutral" environment important for detecting things like leaks?

4. Does sinking a nuclear ship or submarine result in contamination of the surrounding environment? In a story, the USS Ronald Reagan (Nimitz class aircraft carrier) is sunk off the coast of Japan by DF-21 ASBMs. It is described as a "looming environmental disaster". Nuclear submarines have sunk before however and I am unaware of any nautical exclusion zones, although that may have been in very deep water (the Ronald Reagan was sunk in relatively shallow waters).

5. Obviously, weapons for use on the Moon would require extensive redesign due to the nature of the lunar surface. But what about Mars? Would it be possible to land something like an M56 Scorpion or ASU-57 (airborne self propelled guns, completely open crew area) and use it on Mars?

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37 minutes ago, SunlitZelkova said:

A few questions-

1. What is the likelihood that an external nuclear weapon being carried by a tactical aircraft (like the B61 on an F-16 or the 8U69 on a Su-7B) would detonate upon the aircraft being shot down (by damage/hits that do not completely destroy the engine/power supply, but instead aerodynamic surfaces, like a wing)?

A nuclear weapon is a very precise and delicate piece of machinery.  The conventional explosives must detonate in a particular pattern/shape/timing to cause the bomb to become super-critical, his cannot happen by chance, and even minor damage could turn it into a very expensive IED that happens to throw around radioactive materials instead of a nuclear bomb.

They also have lots of built-in safeties.  

If they 'push the button' then it has a good chance to explode(if not damaged).  If the bomb has not been armed, no amount of external stimulation will cause it to detonate.

37 minutes ago, SunlitZelkova said:

2. Do derelict satellites remain stabilized? Last summer, I observed what appeared to be a satellite transiting the Moon through my telescope, and I wonder whether it was junk or active. It did not appear to be tumbling.

A satellite should stay 'stable' until something causes its moment of inertia to change, even if it is out of fuel.  A spin stabilized satellite might stay relatively 'stable' through multiple impacts.

37 minutes ago, SunlitZelkova said:

4. Does sinking a nuclear ship or submarine result in contamination of the surrounding environment? In a story, the USS Ronald Reagan (Nimitz class aircraft carrier) is sunk off the coast of Japan by DF-21 ASBMs. It is described as a "looming environmental disaster". Nuclear submarines have sunk before however and I am unaware of any nautical exclusion zones, although that may have been in very deep water (the Ronald Reagan was sunk in relatively shallow waters).

Water is an excellent radiation shield.  The ocean has an estimated 4 bln tons of uranium, which is roughly 500 times the known mineable ore.  

https://www.pnnl.gov/news/release.aspx?id=4514#:~:text=It's estimated that there is,extracting it from the oceans.

If there is a looming environmental crisis, it seems more likely to be due to other materials on the boat(lead, gunpowder, etc.).

Remember, the reactor was shielded well enough for people to stand right next to it and get less additional radiation than an airline flight, and that was before it got covered in water.

37 minutes ago, SunlitZelkova said:

5. Obviously, weapons for use on the Moon would require extensive redesign due to the nature of the lunar surface. But what about Mars? Would it be possible to land something like an M56 Scorpion or ASU-57 (airborne self propelled guns, completely open crew area) and use it on Mars?

Most engines use atmospheric oxygen, so it will not be traveling anywhere.

Most ammunition includes its own oxidizer, so it should fire just fine.  (I would not expect vacuum welding on mars, but lubricant might freeze or evaporate) 

Parachutes tend not to be sufficient on Mars however, so it may need a different form of delivery.

 

Edited by Terwin
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1 hour ago, SunlitZelkova said:

1. What is the likelihood that an external nuclear weapon being carried by a tactical aircraft (like the B61 on an F-16 or the 8U69 on a Su-7B) would detonate upon the aircraft being shot down (by damage/hits that do not completely destroy the engine/power supply, but instead aerodynamic surfaces, like a wing)?

The conventional explosives can explode, and a lower than 1 t nuclear burst like in the subcritical nuclear tests is possible (when they detonate only one of two charge halves to ensure that all other systems work normal without full-scale explosion).

1 hour ago, SunlitZelkova said:

3. What do spacecraft smell like inside?

Previously - like a public toilet with freshener. But happily the sense of scent weakens in zero-G.
But now they use better ventilation.
And drill more holes when it's insufficient.

1 hour ago, SunlitZelkova said:

4. Does sinking a nuclear ship or submarine result in contamination of the surrounding environment?

https://bellona.org/news/nuclear-issues/2019-08-sunken-soviet-sub-leaking-high-levels-of-radiation-norwegian-researchers-say

1 hour ago, SunlitZelkova said:

5. Obviously, weapons for use on the Moon would require extensive redesign due to the nature of the lunar surface. But what about Mars? Would it be possible to land something like an M56 Scorpion or ASU-57 (airborne self propelled guns, completely open crew area) and use it on Mars?

The partially redesigned aviation cannon has been tested on Almaz flight.

But it was just a self-defence weapon to use it once if something approaches, not to be reloaded and used many times like the ground weapons are.

The atmospheric grease would evaporate in the Martian vacuum, making parts dry and damaging the mechanisms. The Martian dust will do the rest,
The combustion engines can't work properly even on mountains.
The pipes and tanks are not designed to withstamd 1 atm pressure difference.

So, Lunokhod-like things would be required.

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3 hours ago, JoeSchmuckatelli said:

What is a good site to learn about entry level telescopes? 

My Intrepid 11 yo is interested - so I would like something decent but not overly expensive or complex 

While I’m no expert by any means, the one bit of advice that stick about looking at telescopes is to make sure it has a good solid mount (sorry, I don’t have any recommendations). It gets frustrating very fast if it won’t stay where you aim it. 

From my limited experience, I find myself wanting a motorized tracking mount since things seem to move out of the FOV far too quickly due to Earths rotation. I think my mount has a knob for that, if I ever set it up/align it properly. 

But I have been able to pick out the pinpricks of the Galilean moons

Sorry I’m not actually answering your question; I don’t know a good site for that

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4 hours ago, JoeSchmuckatelli said:

What is a good site to learn about entry level telescopes? 

My Intrepid 11 yo is interested - so I would like something decent but not overly expensive or complex 

A lot of the sites I looked at included product suggestions and thus felt a bit dubious, but this seems to give some decent general tips- https://www.planetary.org/articles/how-to-pick-the-perfect-beginner-telescope

This also has good information to know when looking for the right product- https://skyandtelescope.org/astronomy-equipment/choosing-astronomy-equipment/telescopes/types-of-telescopes/

These tips are mainly just for picking out for the right telescope-type (specs/performance) for your kid. The actual "entry level" aspects mainly fall into things like ease of maintenance, etc., and those are really only found by searching for the product itself.

Some personal notes-

1. All telescopes will "by default" have an upside down and/or mirrored image. There are some addons that will amend this for some telescopes (at the cost of reducing the amount of light it can collect), but just something to be aware of in case your kid is expecting a "normal" image.

2. This is obvious, but depending on where you live, even if a telescope "can" see things like galaxies and nebulas, does not mean it "will". Again, something you may want to take into account depending on your kid's expectations.

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8 hours ago, JoeSchmuckatelli said:

What is a good site to learn about entry level telescopes? 

My Intrepid 11 yo is interested - so I would like something decent but not overly expensive or complex 

I have a **very** cheap telescope, but it does have a handful of swap-out lenses, inverters, and the like. I am able to resolve the rings of Saturn and the moons of Jupiter, and I can make out Mars as a fuzzy disc and Venus as a crescent (at least, during its crescent phase). And of course I can resolve practically any lunar crater in shimmering glory.

It is my understanding that as telescopes go, there is a fairly substantial jump in price between something like this, and something that can resolve galaxies and nebulae.

So I would say, either get a really good cheap telescope, or a really cheap good telescope.

On 12/14/2021 at 11:28 PM, Terwin said:

A nuclear weapon is a very precise and delicate piece of machinery.  The conventional explosives must detonate in a particular pattern/shape/timing to cause the bomb to become super-critical, his cannot happen by chance, and even minor damage could turn it into a very expensive IED that happens to throw around radioactive materials instead of a nuclear bomb.

Literally everything in your answer is what I was about to say.

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Is it possible to make geostationary orbit on polar region (either north or south)? Or if it's impossible, is there any satellite network design that achieve basically the same result? (continuous survey of the same landscape on polar region) How many satellites (at the bare minimum) required to achieve it?

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10 minutes ago, ARS said:

Is it possible to make geostationary orbit on polar region (either north or south)?

This might be helpful.

Quote

No, a geostationary orbit must be in the plane of the Earth's equator. That way, by matching its orbital speed with the speed of a point on the equator, the moving satellite appears to be stationary over that point. Any other orbit would have the satellite appear to drift above and below the equator during the course of a day.

A geosynchronous orbit matches the Earth's rotational speed, but only allows a satellite to appear over the same spot once per day. Depending on your stretch of that definition, a satellite in a perfect polar orbit would pass over each pole once per day and might be called 'geosynchronous', but like the time of day at the poles the terminology becomes ambiguous.
Answered by: Paul Walorski, B.A., Part-time Physics/Astronomy Instructor

(https://www.physlink.com/education/askexperts/ae513.cfm#)

 

Edited by Admiral Fluffy
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3 hours ago, ARS said:

Or if it's impossible, is there any satellite network design that achieve basically the same result? (continuous survey of the same landscape on polar region) How many satellites (at the bare minimum) required to achieve it?

If you're going for fewest satellites, two in highly elliptical orbit will do the trick. If they are placed about half of the orbit apart, one of them will already have a good overhead coverage of the polar region while going up as the other one is going down. There might be some choices that have to be made about specific eccentricity and inclination to make sure orbital precession keeps the satellites where you want them, but it shouldn't be too hard to find something suitable.

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On 12/7/2021 at 2:32 AM, K^2 said:

Shouldn't. Some integration methods could have trouble, but I would imagine Wolfram to handle it correctly. Is your load something like c1H(L/2 - x)H(L/2 + x) - c2δ(x-xs) - c2δ(x+xs)? (I'm assuming load isn't structural and sags, distributing weight evenly, and supports are applied at a point.) I can't think of any reason why this would result in solutions that aren't symmetric. One thing you could try, and what I'd do to simplify the problem, is to enforce symmetry by solving for positive x only with additional boundary condition that deflection and slope at x=0 are zero. That way your loading is just a Heaviside + delta, which should be a lot easier to integrate, and then maybe do all the math in Fourier space to go back to continuous functions if I was doing this by hand. Of course, that doesn't help explaining what went wrong in your computation. Do you want to share a bit more details about the steps you've taken?

I don't have my work in a format that I can simply drop into the post editor. However what I can say is that it was the way in which I was finding the constants of integration that seemed to have been the problem. Using the deflection equation and applying the boundary conditions at the supports, letting those be distances a and b from the origin point, is 0 m each, and switching on the appropriate singularity functions and manipulating the equation to get the sum of these functions onto the right hand side, I wind up with a system of two equations:

C1(a) + C2 = Sum of Singularity Functions 1

C1(b) + C2 = Sum of Singularity Functions 2

At first, what I did was put this system into matrix form and then row reduce to obtain C1 and C2. Even though the row reduction was done properly (I'd feed Wolfram the matrix and it spit out constants identical to my hand written solution). However, something was not working as I was failing to get constants that would result in the deflection of the free ends being identical in value. Meaning the resulting deflection equation could not be trusted to compute deflection anywhere along the beam.

I happened to be watching this MindYourDecisions video a couple of days ago that showed a method of solving as system equation I did not consider, solving the system by subtracting one equation by another to eliminate terms. I tried the method out, Subtracting the second equation by the first to eliminate the C2 term, then solve for C1. Once C1 was obtained, I plug that value into the first equation to get C2. It worked. For both a test case and for the project problem, I got identical values for deflection at the overhangs.

Edited by Exploro
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At what point in the study of maths does one run into tensors and tensor fields?

I obviously never went that far - but I'm reading about them .  Just wondering where I would have heard of them had I stuck to the sciences rather than having fun arguing with people in coffee shops.

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Q1: To what extent can modern humans survive the collapse of their food industry?

Q2: To what extent could humanity survive climate change induced ecological collapse and famine?

For the purposes of asking these questions, both take place within the same scenario.

Disclaimer- the scenarios themselves may have inaccuracies, but the point is to present a situation in which people don't have access to their "normal" method of getting food. In any case, please feel free to correct me where they are inaccurate.

Q1

A nuclear war occurs in 1983 between NATO + its associates and the Warsaw Pact. "Nuclear winter" does not occur to the extent required to induce crop failure, but, transport networks have been destroyed or rendered inoperable, and the economy has been shattered so even if there was a functioning food distribution system, people could not "get" food.

Millions of people have survived. What are their options?

From what I can gather, their odds would not be good. Fauna will be quickly depleted if tens of millions go out into the forest to hunt them, and foraging is not a viable option as wild plants do not provide enough nutrition to keep people alive. Are they doomed? What am I missing?

Q2

Billions "survived" in nations that did not take part in the war, but with the death of millions of scientists and the destruction of the international order, climate change awareness never occurs. Thus sometime in the latter half of the 21st century, climate change results in sea level rise, widespread extinction of marine life, and crop failure. Food becomes very scarce everywhere.

So what can people do? Again, fauna (that is, the fauna that hasn't gone extinct in the preceding decades) will be depleted very fast if billions go out into the forest to hunt them. Fishing is not an option as most of them are extinct, verging on extinction, or, for inland species, also be depleted very quickly. Foraging doesn't work, because humans are unable to survive on wild plants alone, and even if they were, that won't get them through the winter.

Are they doomed or am I missing something?

Even if small numbers of humans do survive (perhaps tribes that are already isolated, namely in the Amazon- assuming the Amazon hasn't undergone desertification) what stops them from dying out due to inbreeding depression and lack of genetic diversity some thousand or thousands of years in the future?

My final question can also be applied to something like an asteroid impact or, maybe a supernova. Even if people survive in bunkers, won't humanity go extinct anyways in a relatively short amount of time?

Edited by SunlitZelkova
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1 hour ago, SunlitZelkova said:

Q1

Remember that you eliminated most of the people from the city.  Vast swathes of the US are rural.  The trucking industry has survived because of the number of trucks between cities - but mass distribution centers are gone.  Okay - not the truck industry... But the trucks. 

 

Now - think about Harvey and other hurricanes.  The survivors actually help one another.  

So in places where it's easy to grow food - people survive.  Desert farms dry up and whither. 

Still - more people survive than one might expect. 

1 hour ago, SunlitZelkova said:

widespread extinction of marine life

If that happens you might expect a general collapse of the food web. 

1 hour ago, SunlitZelkova said:

y final question can also be applied to something like an asteroid impact

Ever read Lucifer's Hammer? 

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5 hours ago, SunlitZelkova said:

To what extent can modern humans survive the collapse of their food industry?

To add to what I suggest above, this is from that Cold War era Congressional report on Nuclear War scenarios I linked pages back:

Quote

While the absolute level of surviving stocks of materials and products would seem low by prewar standards, there would be a much smaller population to use these stocks. Apart from medicines (which tend to have a short shelf life and which are manufactured exclusively in urban areas), there would probably not be any essential commodity of which supplies were desperately short at first. A lack of medicines wouId accentuate the smallness and hardiness of the surviving population. Restoring production would be a much more difficult task than finding interim stockpiles

 

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6 hours ago, SunlitZelkova said:

To what extent can modern humans survive the collapse of their food industry?

To the extent which was existing before the modern food industry had appeared, but with much better start conditions due to remaining stuff, staff, and knowledge..
And it appeared in early XX, like almost everything we have. https://en.wikipedia.org/wiki/Modernity
XIX was mostly rural.

6 hours ago, SunlitZelkova said:

Fauna will be quickly depleted if tens of millions go out into the forest to hunt them

1. The Northern forests are not so much easy to "tens of millions go out into the forest to hunt".

2.  Historical practices.

Spoiler

Richard-Strange-and-Christian-Slater-in-

They were uncontrollably hunting in sherwood wood instead of doing their social duties among the corporative team.

The same about private looting.
 

6 hours ago, SunlitZelkova said:

What am I missing?

Technologies, agricultural tech, fertilizer stock, 1913 as the beginning of the synthetic ammonia production, hospitable warm countries to the South ready to help.

6 hours ago, SunlitZelkova said:

but with the death of millions of scientists

Millions of vacancies for former students.

Also to the date the millions of scientists and the billions of survivors are geographically separated, so what happened to the scientists?

6 hours ago, SunlitZelkova said:

sea level rise, widespread extinction of marine life

The marine life now can populate new shallow aquatories, full of soil and other organics.

6 hours ago, SunlitZelkova said:

So what can people do?

The same like always.  The strong takes from the weak.
As there are much more weaks than strongs, and the nature would be mostly being eliminated by the weaks,
and the weaks would be not just fishing/hunting but also gathering everything what's not nailed to the floor (what's nailed - first unnailing from the floor, them gathering),
the ecological patrol ships, patrolling the oceans to save the whales from the braconiers and coasts from pirates.

A typical Coast Guard Ecological Patrol Group.

Spoiler

USS_Enterprise_(CVAN-65),_USS_Long_Beach

See, they just have tested a thing to save the ammo and keep guarding the whales until the reactors need a reload.

Spoiler

uss-portland-laser-shot.jpg?quality=85

 

The same about transboundary crop plantations required to let the eco-friendly societies survive.
"Crops instead of drugs!" agricultural initiative supported with soft power of friendly stormtroopers guarding the territory by persecuting the braconiers outside of perimeter.

6 hours ago, SunlitZelkova said:

tribes

Would get extinct first. Because neighbor to simple rural people with excess of guns and lack of niceness, who need the wood for food.

6 hours ago, SunlitZelkova said:

what stops them from dying out due to inbreeding depression and lack of genetic diversity some thousand or thousands of years in the future?

The absence of the future (see above).

Some nations would unite (say, EU) to support the Armed Active Ecology Protection Initiative. 
Some others (let's not show with finger) would split into "20%" of privileged ones and "80%" of expendable survivors, where the latter are also used for foraging breakthrough with army support of the former.

6 hours ago, SunlitZelkova said:

My final question can also be applied to something like an asteroid impact or, maybe a supernova. Even if people survive in bunkers, won't humanity go extinct anyways in a relatively short amount of time?

While the ocean stays liquid, and the atmosphere stays breathable, why?

 

5 hours ago, JoeSchmuckatelli said:

Okay - not the truck industry.

If comparre the truck plants of early XX and modern truck servicing centers, not that it would gone. Just temporary thrown back and redistributed.

5 hours ago, JoeSchmuckatelli said:

Now - think about Harvey and other hurricanes.  The survivors actually help one another.  

While they have enough resources to help.

https://en.wikipedia.org/wiki/John_Steinbeck#Major_works

Edited by kerbiloid
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2 hours ago, kerbiloid said:

The marine life now can populate new shallow aquatories, full of soil and other organics.

Those hypothetical widespread extinctions are related to ocean acidification.

2 hours ago, kerbiloid said:

The absence of the future (see above).

I didn't understand that portion of the answer, but also I myself may not have been clear.

Foraging referred to gathering wild plants. Humans can not survive on that alone.

Now, the answers provided have basically answered question 1, so what follows is within the context of question 2.

With millions of people looking for food, fauna will run out quickly. They can't survive by foraging, and the marine food sources will either be depleted in a similar manner to land animals or be extinct due to the situation in the scenario. Continued farming- at least, enough to feed the entire population- won't be feasible, as either the climate won't allow for it, arable land is gone, or the pollinators are in rapid decline.

What methods of feeding for humans am I missing that might be usable to save millions of people?

3 hours ago, kerbiloid said:

While the ocean stays liquid, and the atmosphere stays breathable, why?

Bunkers don't exactly hold millions. When I said "relative" I meant relatively within the existence of members of the genus Homo for 2.8 million years. So even if people can survive somehow afterwards, inbreeding depression and lack of genetic diversity in the future will doom the species in time.

------

Thanks to you two for the answers on question 1. I clearly missed a lot!

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3 hours ago, SunlitZelkova said:

Foraging referred to gathering wild plants. Humans can not survive on that alone.

Why gather wild plants instead of burning them to use the soil as a plowland for usuak crops?

https://en.wikipedia.org/wiki/Slash-and-burn (by undeveloped peasants) or for modern crop farming.

3 hours ago, SunlitZelkova said:

They can't survive by foraging, and the marine food sources will either be depleted in a similar manner to land animals or be extinct due to the situation in the scenario.

Many people live far from sea and don't depend much on the sea food. It's just a cheap extra food, nothing more. Crops rule.

3 hours ago, SunlitZelkova said:

Bunkers don't exactly hold millions. When I said "relative" I meant relatively within the existence of members of the genus Homo for 2.8 million years. So even if people can survive somehow afterwards, inbreeding depression and lack of genetic diversity in the future will doom the species in time.

So even if people can survive somehow afterwards, inbreeding depression and lack of genetic diversity in the future will doom the species in time.

80k years ago just 10k humans had survived after the supervolcano.

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