For Questions That Don't Merit Their Own Thread

[Shpaget]

1 hour ago, ARS said:

A bomb mechanism where at the end of it, there's 2 wires that when one is cut, it just stops the timer and if the other is cut, the bomb explodes instantly

If there are two detonators in parallel, you could monitor continuity through each, and if a wire is cut a microcontroller activates the boom.

Finding a wire that is safe to cut would depend on the design, and I'd assume a half competent electronics engineer could come up with a design that is guarded against this approach.

That being said, high explosives are very safe and will not explode unless a detontor goes off in close proximity.

In an unlikely scenario were I find myself in a jigsaw type of picle, I'd try removing the detonator without cutting anything. Otherwise, instead of wire cutters, I'd make use of a pair of running shoes.

[kerbiloid]

3 hours ago, SunlitZelkova said:

*shrugs* helping to know orientation?

To be clear, I meant the green and red. The Gemini, Apollo CSM and LM, Crew Dragon, and maybe Starliner have them.

To know whose orientation when nobody is around, and the lights are always at their places from the crew pov from inside?

***

Soyuzes had the colored lights since the earliest ones.

Soyuz-3 (Beregovoy) and Soyuz-2 (uncrewed) were planned to dock, but Beregovoy confused the Soyuz-2 navigation/docking lights and was trying to dock overturned (at the night side of the planet).
So, the objective was failed, and he just returned to the Earth.
Since that they were planning the dockings on the day side.

2 hours ago, ARS said:

What I want to ask is, does this mechanism really exist in real-life bombs?

Since WWII if not earlier.

https://en.wikipedia.org/wiki/Anti-handling_device

Colored wires were in sea bottom mines, afaik.

Edited April 28, 2021 by kerbiloid

[ARS]

4 hours ago, magnemoe said:

For other stuff like the bomb to blow up the asteroid its no point having it hard to disarm as its nobody who can do it anyway as the bomb would be on an probe in space

It's a joke on nuclear bomb disarming scene on movie Armageddon

Edited April 28, 2021 by ARS

[DDE]

15 hours ago, SunlitZelkova said:

Do any Soviet/Russian spacecraft have/had navigation/running lights? There don't seem to be any from what I can find, only the docking light.

I know there were a few during the early dockings. Beregovoh messed up and approached his target upsidedown because he read those lights wrong.

[magnemoe]

10 hours ago, Shpaget said:

If there are two detonators in parallel, you could monitor continuity through each, and if a wire is cut a microcontroller activates the boom.

Finding a wire that is safe to cut would depend on the design, and I'd assume a half competent electronics engineer could come up with a design that is guarded against this approach.

That being said, high explosives are very safe and will not explode unless a detontor goes off in close proximity.

In an unlikely scenario were I find myself in a jigsaw type of picle, I'd try removing the detonator without cutting anything. Otherwise, instead of wire cutters, I'd make use of a pair of running shoes.

This, also unless you are in an populated area just blowing it up works well enough.
Most cases its very old dudes found as in WW2 stuff, who is now very unstable as its rusted for 60 years. 
Or in more modern settings shooting up cars with tanks is reinforcing the parking rules  

 

[JoeSchmuckatelli]

13 hours ago, Shpaget said:

two detonators in parallel, you could monitor continuity through each, and if a wire is cut a microcontroller activates the boom.

I'd sure want some specialized equipment before trying this.  Definitely not something jury rigged by the meth head in my group. 

 

(My experience with detonators suggests it does not take a whole lot electricity to kick off the charge.) 

 

 

 

[Shpaget]

Hmm, your and mine definition of "not a whole lot" may be different.

Datasheets I've seen all say that safe, no fire current is at least 0,2 A, which is huge compared to currents used for sensing.

 

[JoeSchmuckatelli]

6 hours ago, Shpaget said:

Hmm, your and mine definition of "not a whole lot" may be different.

Datasheets I've seen all say that safe, no fire current is at least 0,2 A, which is huge compared to currents used for sensing.

 

Okay using data sheets is cheating... Or perhaps very 'Army' of you. 

 

I mostly worried about making sure that some helpful idiot didn't hook up the detonator and play with it while I was setting the charge. 

 

 

[kerbiloid]

Don;t they always cut the red?

[K^2]

6 hours ago, JoeSchmuckatelli said:

I mostly worried about making sure that some helpful idiot didn't hook up the detonator and play with it while I was setting the charge. 

It should be relatively easy to add a bit of a grace time after the device is activated in which the fault-checks are active and maybe even notify you that there is a problem, but don't trigger detonation. So if you are installing a demo charge you don't want anybody else removing, maybe you have ten seconds to make sure everything's working properly in which you can safely shut it off.

Granted, we're now adding software complexity on top of circuit complexity, but IMO, that's still the way to go. You can test all your software separately in simulation. This isn't a rocket launch - there are only so many fault conditions, and you can enumerate them all and make sure your software responds correctly.

None of this is going to stop someone from just cutting the secondary with a water jet, of course, but I take it we're just talking about potential enemy finding the device early and trying to prevent destruction of critical asset by cutting wires, etc. For this job, multiple detonators, sense currents, and a simple microcontroller are entirely adequate, and it's easy enough to write the software to quality where you won't have to worry about someone's crap wiring job.

[JoeSchmuckatelli]

I've read that the regular, annual meteor showers are remnants of comets, such as the Eta Aquarid - which has been traced to Halley's Comet.

Question is: how does debris from a comet spread out along the orbital path?

From what little I know about orbital mechanics:

• The comet's orbital path must cut across Earth's so that once (or twice) a year we intersect the path of debris and experience the meteor shower
• Objects in the same orbit all travel at the same speed

... and here's the source of my confusion.  If we get an annual / biannual meteor shower from a comet, what you have is, effectively, a 'ring' of debris with the comet itself being just the most clustered/concentrated part of the ring.  So how does something that we thing of as 'a thing' get broken up into a ring without all the pieces just being flung all over the solar system?

[kerbiloid]

A cloud of bodies moving around the Sun on orbits with very close parameters, and
either orbiting around the comet itself (those with low relative speed, insufficient to leave the Hill sphere of the comet),
or moving separaedly from the comet (if their original speed exceeded the comet escape speed, which is actually several tens of m/s ).

The planets gravity and the tidal forces of the Sun make the cloud blurry by changing the particles speed randomly.

[JoeSchmuckatelli]

54 minutes ago, kerbiloid said:

A cloud of bodies moving around the Sun on orbits with very close parameters, and
either orbiting around the comet itself (those with low relative speed, insufficient to leave the Hill sphere of the comet),
or moving separaedly from the comet (if their original speed exceeded the comet escape speed, which is actually several tens of m/s ).

The planets gravity and the tidal forces of the Sun make the cloud blurry by changing the particles speed randomly.

So... Given Halley's long period, would it be correct to assume that the ice and rocks that we see while the comet itself is far away are not actually part of the comet, but merely co-orbiting remnants of the solar system's formation?  Because if that's true: how or what is making this ring find or remain in Halley's orbital path such that we uniquely encounter these things during our intersections with the orbit, rather than passing through a constant rain of meteors?

or if this is the case:

59 minutes ago, kerbiloid said:

The planets gravity and the tidal forces of the Sun make the cloud blurry by changing the particles speed randomly.

then the particles are / were part of the comet itself -- so how do some of them find themselves on the complete opposite side of the orbit from the comet that we can still experience the Eta Aquarid while Halley's is at its extreme distance from the sun?

[kerbiloid]

25 minutes ago, JoeSchmuckatelli said:

o... Given Halley's long period, would it be correct to assume that the ice and rocks that we see while the comet itself is far away are not actually part of the comet, but merely co-orbiting remnants of the solar system's formation? 

Unlikely of the star formation. Just the comet remnants from random hits (including the hits from other remnants), drifting along the nearly same orbit due to slightly differing orbital periods.
The Hal's commy orbital period is 75 years = 900 months, so every month of the period difference means 0.001 difference in the angular drift rate per turn.

32 minutes ago, JoeSchmuckatelli said:

Because if that's true: how or what is making this ring find or remain in Halley's orbital path

Not a ring, a part of torus along their orbit with the comet in the middle, trying to fill the whole orbit like a full torus.

34 minutes ago, JoeSchmuckatelli said:

so how do some of them find themselves on the complete opposite side of the orbit from the comet that we can still experience the Eta Aquarid while Halley's is at its extreme distance from the sun?

A part of the comet totally disintegrated after drifting?

Like the so-called "Teya" (i.e. the proto-Moon) who presumably drifted from the Lagrange point of the Earth orbit due to different but close orbital period.

[JoeSchmuckatelli]

55 minutes ago, kerbiloid said:

Not a ring, a part of torus along their orbit with the comet in the middle, trying to fill the whole orbit like a full torus

Thanks for the term: it's more in line with what I meant: a 'ring' around the sun, rather than a ring around the comet, like Saturn's.  Torus is closer to what I meant to communicate.

57 minutes ago, kerbiloid said:

The Hal's commy orbital period is 75 years = 900 months, so every month of the period difference means 0.001 difference in the angular drift rate per turn.

So the meteors really could be part of the comet then, given the total time it's been orbiting.  Small perturbations over time, just enough to tug one piece into a slightly longer period, or drop another into a lower orbit, and then over time the shards fill the full orbit?

[kerbiloid]

30 minutes ago, JoeSchmuckatelli said:

Small perturbations over time, just enough to tug one piece into a slightly longer period, or drop another into a lower orbit, and then over time the shards fill the full orbit?

Like rings of Saturn appeared from the disintegrated ice moon and unformly filled the orbit.
Just they are much closer to the gravity center, so the torus is flattened.

[JoeSchmuckatelli]

42 minutes ago, kerbiloid said:

Like rings of Saturn appeared from the disintegrated ice moon and unformly filled the orbit.
Just they are much closer to the gravity center, so the torus is flattened.

This makes a lot of sense: Now I can explain it to my kids!

 

[kerbiloid]

39 minutes ago, JoeSchmuckatelli said:

This makes a lot of sense: Now I can explain it to my kids!

 

Also,  as the regular shower appears in the sky at the same date every year (i.e. every Earth turn), this means that this meteor particles are already distributed uniformly along their orbit.

I.e. its appearance depends only on the Earth orbital position.

The irregular ones are just young and haven't filled the whole orbit.

The periodic ones are old and thus regular.

Edited May 1, 2021 by kerbiloid

[SOXBLOX]

3 hours ago, JoeSchmuckatelli said:

...then the particles are / were part of the comet itself ...

I think what happens is these particles are carried off by outgassing. They get a bit of Δv from that, and it puts them in a very slightly different orbit. Then you have radiation pressure, like how the Sun pushes a lightsail, and the Yarkovsky Effect. The tiny, featherweight particles that become meteors are more affected by this than the massive comet is. So, they get enogh ∆v to leave the vicinity of the comet, but it isn't enough to change their solar orbit (much).

I think. Take this with a bucket of salt.

Edited May 1, 2021 by SOXBLOX
Jest 'Cuz.

[StrandedonEarth]

4 hours ago, SOXBLOX said:

I think what happens is these particles are carried off by outgassing. They get a bit of Δv from that, and it puts them in a very slightly different orbit. Then you have radiation pressure, like how the Sun pushes a lightsail, and the Yarkovsky Effect. The tiny, featherweight particles that become meteors are more affected by this than the massive comet is. So, they get enogh ∆v to leave the vicinity of the comet, but it isn't enough to change their solar orbit (much).

I think. Take this with a bucket of salt.

Sounds about right to me, with my limited knowledge 

[K^2]

9 hours ago, SOXBLOX said:

I think what happens is these particles are carried off by outgassing. They get a bit of Δv from that, and it puts them in a very slightly different orbit. Then you have radiation pressure, like how the Sun pushes a lightsail, and the Yarkovsky Effect. The tiny, featherweight particles that become meteors are more affected by this than the massive comet is. So, they get enogh ∆v to leave the vicinity of the comet, but it isn't enough to change their solar orbit (much).

I think. Take this with a bucket of salt.

The only thing I have to add is that energy and anomaly are two conjugate orbital elements. So slight changes in energy of particles will result in them spreading out along the orbit with very little impact on other parameters. Naturally, over long enough time frame, you expect the debris to defuse all over the star system, but diffusion along the orbit is the fastest process here.

[SOXBLOX]

Robots are cleaning F-16s here in Texas! Kinda cool; saves a lot of time. Here.

[JoeSchmuckatelli]

Fly-through?  Extra service with a full tank of gas? 

[kerbiloid]

(Already posted earlier)

The robots can not just wash. They can many other things.

Spoiler

 

 

[magnemoe]

7 hours ago, JoeSchmuckatelli said:

Fly-through?  Extra service with a full tank of gas? 

Now I wonder that will happen if you have another loadout than 2 drop tanks? 
Yes its pretty simple to test for and its not like you will wash it with live weapons anyway.