For Questions That Don't Merit Their Own Thread

[Racescort666]

2 hours ago, magnemoe said:

Emp should work but would hit other stuff too unless beamed. 
Nets would help, staying indoors, in an car or other places they can not get would work, problem is that they can defeat windows who are not bullet proof or laminated. 
Any sort of body armor including sturdy clothes and helmets with face cover. If nothing else an bucket over you head.
The slaughterbots used an very small shaped charge or an explosively shaped penetrator. 
Range and penetration is minimal. An somewhat larger one would carry an larger warhead to defeat armor and even fire at range, 

Note that this is an military weapon, making an so miniaturized shaped charge or not to talk about penetrator and integrate it is hard to do in small scale but fairly easy to do with mass production. 
An terrorist would rater use one or a few larger drones with an easier to get explosive. 

Now the question is why military would want to use them. See two settings one is hard to reach and dangerous places like underground, second would be to reduce collateral damage they would work very well in hostage or human shield situations. 
Else you could just empty some B52 over target. 

Defeating the tracking system is usually the best way I’d say. That’s basically how most aircraft countermeasures work. 

[DDE]

On 11/20/2017 at 12:21 PM, NSEP said:

Did the Soviets ever had or used SRB's in/on their rockets? It almost seems like the Soviets never had SRB's.

Never, not even once except for Strela, a Topol conversion. The closest you get are the pretty big solid rockets used as Buran’s emergency separation motors.

3 hours ago, magnemoe said:

An terrorist would rater use one or a few larger drones with an easier to get explosive. 

Relevant: 

 

A few well-placed mortar rounds or cluster bomblets can go a long way.

[Deddly]

Off-topic cross-post removed

[ChrisSpace]

17 hours ago, magnemoe said:

Emp should work but would hit other stuff too unless beamed.

Explosives can be "shaped" to direct most of their energy in a certain direction, perhaps the same can be done with EMPs?

17 hours ago, magnemoe said:

Nets would help, staying indoors, in an car or other places they can not get would work, problem is that they can defeat windows who are not bullet proof or laminated. 

In the video I perceived them as being like a flying anti-tank mine, so windows aren't the only thing they can get through.

17 hours ago, magnemoe said:

Any sort of body armor including sturdy clothes and helmets with face cover. If nothing else an bucket over you head.

Again, I think they could break through that.

 

15 hours ago, Racescort666 said:

Defeating the tracking system is usually the best way I’d say. That’s basically how most aircraft countermeasures work. 

This could work, I think.

Also, here's an idea my mum thought of: A modified water hose that shoots really strong acid instead of water. Probably impractical but worth mentioning.

Edited November 23, 2017 by ChrisSpace

[shynung]

1 hour ago, ChrisSpace said:

Also, here's an idea my mum thought of: A modified water hose that shoots really strong acid instead of water. Probably impractical but worth mentioning.

Going all the way on that idea: just dump some chlorine trifluoride in their general direction. It'll eat through most materials, and thoroughly corrode what is left behind.

[magnemoe]

5 minutes ago, ChrisSpace said:

Explosives can be "shaped" to direct most of their energy in a certain direction, perhaps the same can be done with EMPs?

In the video I perceived them as being like a flying anti-tank mine, so windows aren't the only thing they can get through.

Again, I think they could break through that.

 

This could work, I think.

Also, here's an idea my mum thought of: A modified water hose that shoots really strong acid instead of water. Probably impractical but worth mentioning.

Explosive charge is small as in far less than 1 cm^3, you can get half the energy in an narrow beam in one direction, that is an narrow beam making an hole like an low caliber gun. 
This will do for windows who chatter, not much other stuff do. Don't see they getting trough an plank wall without having very good control and using hundreds of them. 
Yes swarming them will defeat body armor, again you want to mass them to make sure you kill the target, this can be hard. 

You would want to jam gps this harms overall deployment, you would also want to jam inter communication so they can not cooperate well. 
Paint would work well in the water gun, block the optic. 

Now having your own drone, not with explosives but with sharp steel propellers might be the best option if you can targeting the enemy drones well enough. An mobility kill would work more than well enough and your drone will probably survive the encounter and can engage the next. Yes it would not work well against an large swarm. 

 

[Racescort666]

I’ve got it:

[Grand Ship Builder]

What would happen if you put salt in an outlet? Would the electricity cause the chlorine and sodium to break up?

[K^2]

17 hours ago, Grand Ship Builder said:

What would happen if you put salt in an outlet? Would the electricity cause the chlorine and sodium to break up?

No. You need to melt salt for it to undergo electrolysis. That is done, and is one of the ways of acquiring metallic sodium, but you'll have to heat salt to about 800°C for it to melt. In solid form, salt is an excellent insulator and will require voltages far greater than these available in the outlet to cause a breakdown across any significant distance, and even then, only a narrow ion channel will be formed.

The other problem is that electrolysis, if that's your goal, requires DC current. What you get out of an outlet is AC. So you'll need a transformer and a rectifier bridge. If you apply an AC voltage to molten salt, current will flow, but no net production of sodium or chlorine will follow.

P.S. NOTE: Chlorine gas is extremely corrosive and toxic. I'm realizing that with sufficient motivation, it's easy enough to heat salt to a melting point, and I should put in a warning that salt electrolysis should not be carried out without a fume hood and proper training in operating one. Id est, don't do this at home, for crying out loud.

Edited November 27, 2017 by K^2

[Racescort666]

2 hours ago, K^2 said:

P.S. NOTE: Chlorine gas is extremely corrosive and toxic. I'm realizing that with sufficient motivation, it's easy enough to heat salt to a melting point, and I should put in a warning that salt electrolysis should not be carried out without a fume hood and proper training in operating one. Id est, don't do this at home, for crying out loud.

I feel like this is something I would see on Cody’s Lab.

[KG3]

I have a question about traveling between objects orbiting as far away from the sun as the Oort cloud.  If I were orbiting Kerbin and I was trying to  rendezvous with another satellite I would line up our orbital planes and then raise or lower my periapsis to change my altitude and speed relative to my target.  Would you need to do basically the same thing if the orbits were 50,000 A.U away from the sun?    

[K^2]

4 hours ago, Racescort666 said:

I feel like this is something I would see on Cody’s Lab.

That's a warning statement in and of itself.

[NSEP]

How much energy would you need to split 1kg of FeO into Fe and O?

Is rust magnetic?

[Grand Ship Builder]

What would happen if two objects, one in a polar orbit, and another in a prograde orbit, docked, while somehow not getting destroyed. Would the collision cause the crafts to get de-orbited?

[Racescort666]

20 minutes ago, Grand Ship Builder said:

What would happen if two objects, one in a polar orbit, and another in a prograde orbit, docked, while somehow not getting destroyed. Would the collision cause the crafts to get de-orbited?

My gut says no, you would have vector addition of the momentum of the 2 objects. I suspect you would change the combined orbit to a 45 degree inclination with 1.414 V_orbit velocity at the intersection point. I'm not as good at calculating orbits as some other people on this forum but I can do vector addition.

[Niccolo]

13 hours ago, KG3 said:

I have a question about traveling between objects orbiting as far away from the sun as the Oort cloud.  If I were orbiting Kerbin and I was trying to  rendezvous with another satellite I would line up our orbital planes and then raise or lower my periapsis to change my altitude and speed relative to my target.  Would you need to do basically the same thing if the orbits were 50,000 A.U away from the sun?    

Essentially, yes. If you wanted to rendezvous with, say, an icy comet that's chilling in the inner Oort cloud (~50,000 AU) then it's much like KSP - burn, and burn, and burn, and burn until your apogee is way out there, then burn once you're out there to match velocity. Of course, you'd better have about 10 millenia's worth of books and batteries, since your travel time is going to be ridiculous.

You could also do as the Voyager craft and New Horizons did and use a gravity assist to save on /\V expenditure. This will rapidly increase your travel time however, and you'd only be able to launch at certain times to take advantage of these windows.

Spiralling on from that, a third (more expensive) option is to burn powerfully and put yourself on an escape trajectory out of the sun. Voyager 1 and 2 did this, essentially - they shot out of the solar system at ludicrous velocities thanks to a lot of burning and a veritable cornucopia of planetary alignments allowing Voyager 2 to hit Jupiter, Saturn, Uranus and Neptune for a chain of gravity assists. The more you burn, the faster you'll get out there, but the more you'll have to burn when you're out there in order to slow down and convert your outwards momentum into orbital momentum and thus match your target's velocity.

As a side note, Voyager 1 has since hit the interstellar medium and thus exited the sun's direct influence (and is considered the first interstellar craft!), but has not actually encountered the Oort cloud yet. NASA anticipates Voyager 1 will be all up in the comet nursery's grill in about 14,000 years.

 

If instead you're aiming for the outer Oort cloud (~200,000 AU), then... uh... good luck. We're not entirely sure if the outer Oort cloud is actually even orbiting the sun, since it's about 3.2 ly out, and thus entirely at the whims of the gravitational field of basically everything that passes by.

But again, same principle. Burn like hell to make your way out there, turn around and burn to slow down.

 

6 hours ago, Racescort666 said:

My gut says no, you would have vector addition of the momentum of the 2 objects. I suspect you would change the combined orbit to a 45 degree inclination with 1.414 V_orbit velocity at the intersection point. I'm not as good at calculating orbits as some other people on this forum but I can do vector addition.

Assuming that the objects had the same mass and orbits, then yeah, their orbital velocity at that point would be at a 45 degree angle and 1.414x increase. Different starting orbits means different vector addition.

Things get weird on the other side of the planet, though. Sudden increase in velocity means that the apoapsis is going to shoot out to compensate.

[peadar1987]

15 hours ago, NSEP said:

How much energy would you need to split 1kg of FeO into Fe and O?

Is rust magnetic?

FeO has a bond dissociation energy of 409 kJ/mol, and a molecular mass of 72, which means 13.9 mol/kg, so to split 1kg you'd need just shy of 5.7MJ of energy (assuming 100% efficiency, which naturally you wouldn't get)

Rust is not magnetic.

 

[KG3]

14 hours ago, peadar1987 said:

FeO has a bond dissociation energy of 409 kJ/mol, and a molecular mass of 72, which means 13.9 mol/kg, so to split 1kg you'd need just shy of 5.7MJ of energy (assuming 100% efficiency, which naturally you wouldn't get)

Rust is not magnetic.

 

Can't you just toss in some powdered aluminum and ignite it? 

[Niccolo]

On 11/28/2017 at 5:12 AM, NSEP said:

How much energy would you need to split 1kg of FeO into Fe and O?

Is rust magnetic?

 

17 hours ago, peadar1987 said:

FeO has a bond dissociation energy of 409 kJ/mol, and a molecular mass of 72, which means 13.9 mol/kg, so to split 1kg you'd need just shy of 5.7MJ of energy (assuming 100% efficiency, which naturally you wouldn't get)

Rust is not magnetic.

 

 

2 hours ago, KG3 said:

Can't you just toss in some powdered aluminum and ignite it? 

 

KG3 's solution is technically correct, and is one type of thermite reaction (the other being Iron (III) Oxide instead of Iron (II) oxide). However, peadar1987 is still correct, you would still need about 5.7MJ of energy in a 100% efficient conversion. It's just that in this instance that energy is provided by the reaction of:

2 AL + 3 O --> AL₂O₃ + (lovetons of heat)

The result would be a crucible (You are doing this in a crucible, right?) that, assuming it hasn't exploded due to containing a 2,500^oC flame, is now full of molten aluminium oxide slag and little pellets of iron that are really, really hot.

 

Regarding the magnetism of rust, peadar1987 is pretty much correct. What we conventionally call rust (the red stuff) is, to all intents and purposes, essentially non-magnetic. Conventional 'red' rust is Iron (III) oxide, or Fe₂O₃, in a hydrated matrix written as Fe₂O₃.H₂O. The  Fe₂O₃ crystal by itself is called haematite and is itself basically non-magnetic but will very, very weakly respond to an external magnetic field. The hydrated form (red rust) is also itself non-magnetic, but as it has that haematite core unit will still respond to an external magnetic field. However, this response is so weak that it requires really powerful electromagnets to generate.

To summarise though, red rust isn't magnetic in the everyday sense.

 

Edited November 29, 2017 by Niccolo

[KG3]

On ‎11‎/‎27‎/‎2017 at 11:25 PM, Niccolo said:

 

 

...As a side note, Voyager 1 has since hit the interstellar medium and thus exited the sun's direct influence (and is considered the first interstellar craft!), but has not actually encountered the Oort cloud yet. NASA anticipates Voyager 1 will be all up in the comet nursery's grill in about 14,000 years....

 

 

 

 NASA says that Voyager 1 is "aiming toward the constellation Ophiuchus" but isn't it just now orbiting the center of the galaxy along a different path than our solar system?  I mean you can't just point in the direction of Ophiuchus and expect to get there right?  If Voyager 1 were being sent to Ophiuchus wouldn't it need to raise or lower it's periapsis and change it's orbital plane in respect to it's orbit around the galaxy and set up an intercept with Ophiuchus?  It takes something like 225 million years to orbit the galaxy!  Ever since playing KSP I'm beginning to realize that space travel is nothing like how they show it on TV.  I guess I'd definitely want to bring a book on tape if I was making that trip.    

[Niccolo]

1 hour ago, KG3 said:

 

 NASA says that Voyager 1 is "aiming toward the constellation Ophiuchus" but isn't it just now orbiting the center of the galaxy along a different path than our solar system?  I mean you can't just point in the direction of Ophiuchus and expect to get there right?  If Voyager 1 were being sent to Ophiuchus wouldn't it need to raise or lower it's periapsis and change it's orbital plane in respect to it's orbit around the galaxy and set up an intercept with Ophiuchus?  It takes something like 225 million years to orbit the galaxy!  Ever since playing KSP I'm beginning to realize that space travel is nothing like how they show it on TV.  I guess I'd definitely want to bring a book on tape if I was making that trip.    

I mean yeah, at it's core the principle of space travel anywhere within a single galaxy is pretty much constant - align your orbit with the target's and burn for an intercept.  The only hiccup comes courtesy of the old N-body problem - and when N is a couple of trillion, then actually mapping your orbit and trajectory gets helluva messy.

Voyager 1 "aiming for the constellation Ophiuchus" though may just mean that its trajectory out of the solar system is in that direction. Although the constellations have no actual influence on our day-to-day lives (no matter what Griselda the tarot reader tells you) they are handy celestial markers for the trajectory of spacefaring objects. Alternatively it may actually be aiming for a flyby of one of the stars of the constellation, which is what some news articles seem to suggest. I'm not really sure.

 

[KG3]

Are Gravity waves effected by gravitational lensing the same way light is?  Is it possible that LIGO could detect multiple signals from a single event if there were something massive enough along it's line of sight?   

[Niccolo]

1 hour ago, KG3 said:

Are Gravity waves effected by gravitational lensing the same way light is?  Is it possible that LIGO could detect multiple signals from a single event if there were something massive enough along it's line of sight?   

I'm by no means an astrophysicist so this is well outside of my comfort zone...

In regards to your first question, it would appear so, yes. Gravitational waves of small enough wavelength and amplitude appear to be affected by gravitational lensing, judging by the very extensive answer given to this Stackexchange physics question. A further Google search reveals a lot of scary math, but the general consensus seems to be yes.

Extrapolating from that, LIGO could potentially detect lensed gravitational waves. Which is awesome.

[KG3]

18 minutes ago, Niccolo said:

I'm by no means an astrophysicist so this is well outside of my comfort zone...

In regards to your first question, it would appear so, yes. Gravitational waves of small enough wavelength and amplitude appear to be affected by gravitational lensing, judging by the very extensive answer given to this Stackexchange physics question. A further Google search reveals a lot of scary math, but the general consensus seems to be yes.

Extrapolating from that, LIGO could potentially detect lensed gravitational waves. Which is awesome.

Thanks!  I've never heard of the Stackexchange before but this certainly does answer my question.

  "So if the light from a region arriving at your instruments is increased through the gravitational effects of something between you and the scrutinized region, so too will the gravitational waves be increased through the same partial focusing.  In particular, you can no more burn space ants with gravitational waves through a gravitational lens than you can with light through a gravitational lens!"

I'm looking forward to hearing about more discoveries from gravitational wave astronomy.  Too bad about the space ants though.

[KG3]

I was wondering if this had ever been tried before and so I googled it before asking.  I couldn't find it in the forums here and thought it was kind of interesting.

https://en.wikipedia.org/wiki/Paper_plane_launched_from_space

"Some 30^[3] to 100^[4] planes had been considered to make the descent, each gliding downward over what was expected to be the course of a week to several months. If one of the planes survived to Earth, it would have made the longest flight ever by a paper plane, traversing the 250 mi./400 km. vertical descent. In a test in Japan in February 2008, a prototype about 2.8 inches long and 2 inches wide survived Mach 7 speeds and temperatures reported to be 200°C in a hypersonic wind tunnel for 10 seconds. Materials designed for use in conventional reentry vehicles, including ceramic composites, withstand temperatures on the order of 2200°C.^[5] The 30 cm planes were to have been made from heat-resistant paper treated with silicon."

They were going to launch the planes from the ISS but decided not to because they couldn't track them to the surface.  There is also a group in Germany called Project Space Planes that dropped 200 paper airplanes 37,339 meters from a weather balloon.  It doesn't seem like they have any real good data on how far any of them went though.   

https://en.wikipedia.org/wiki/Project_Space_Planes