For Questions That Don't Merit Their Own Thread

[Terwin]

On 4/1/2022 at 9:50 AM, GearsNSuch said:

Rings in a binary planetary system. The cursory Google search didn’t yield anything. How would these work? Theoretically the ring would just orbit the center of mass, but would a figure-8 configuration be stable as well? I ran a (highly inaccurate) particle-based simulation that seemed to indicate both would work, but I’d be interested to see if there’s hard data on this. 

I am pretty sure that it would need to be at a point where a figure-8 orbit would be (more or less) stable.

Larry Niven proposed ring-worlds which are basically a torus possibly with a shepherd planetary-core.  I do not think that such a structure would be long-term stable however, and would eventually recoalesce around the planetary core back into a gas giant.  (then again, the rings of Saturn are just a transitory feature, so perhaps such a gas torus would last a very long time)

[DDE]

We know the last few years have seen several instances of footage of launches from the International Space Station.

However, has anyone ever tried filming an ICBM?

(inspired by an annoying Telegram thread where most people couldn't believe a NorK ICBM could've reached 6000 km, because that's "higher than the ISS"... and instead insisted it flew at 6000 m )

Edited April 5, 2022 by DDE

[kerbiloid]

They have. But you won't see. Maybe a half-centrury later...

Btw, recall the original purpose of Mir/Spektr, with IR scopes and calibration aim launcher, before it had been cut into scientific.

P.S.
Interesting facts.
Did you know, that during the ICBM launch you can not just film a beautiful footage, but also make a wish on the falling star?

Edited April 5, 2022 by kerbiloid

[DDE]

1 hour ago, kerbiloid said:

They have. But you won't see. Maybe a half-centrury later...

That's why we have the ISS. They can't all have signed the same NDA 

[DDE]

Mars is still churning a little

https://www.nature.com/articles/s41467-022-29329-x

Edited April 5, 2022 by DDE
No Mrs yet

[kerbiloid]

Now it's clear, why have the Martian channels disappeared.

A landslide.

[SunlitZelkova]

During Operation Crossroads, a nuclear bomb was detonated underwater. It was mounted aboard a landing craft, which was apparently completely destroyed because almost no trace of it was ever found. The landing craft was pretty small (62 meters length). But what about if a large ship (~330-340 meter length) like an aircraft carrier is hit at near point blank by a nuclear weapon? What would the damage look like?

IIRC most Soviet anti-ship nuclear weapons had a yield in the 200-300 kiloton range.

[darthgently]

25 minutes ago, SunlitZelkova said:

During Operation Crossroads, a nuclear bomb was detonated underwater. It was mounted aboard a landing craft, which was apparently completely destroyed because almost no trace of it was ever found. The landing craft was pretty small (62 meters length). But what about if a large ship (~330-340 meter length) like an aircraft carrier is hit at near point blank by a nuclear weapon? What would the damage look like?

IIRC most Soviet anti-ship nuclear weapons had a yield in the 200-300 kiloton range.

No math, but I'm guessing that the steel pieces would be very small and all having signs of having partially melted if not having gone completely liquid or vaporized.  Parts underwater far from the impact might not be as affected, but they'd still not be very large pieces.   Total guess

[kerbiloid]

https://en.wikipedia.org/wiki/Operation_Crossroads#Able_target_array

The list of ships and distances.

[ARS]

Does the flight trajectory of an object is affected by the rate of acceleration and how the atmospheric drag behaves during the flight? For example, there are 2 projectiles launched into space at suborbital trajectory. Both has the same delta-V, same mass and same angle of launch. However, projectile A is launched normally using rocket engines while projectile B is shot using mass driver. In this case:

1. Projectile A has a gradual acceleration to max speed and atmospheric drag that steadily rises as it flies through atmosphere before it finally reached space

2. Projectile B has instantaneous acceleration to max speed and the atmospheric drag is instantaneously jumped to max before it finally reached space

Assuming these 2 have the same delta-V (but different flight characteristic), does the trajectory produced are identical to each other?

[AngrybobH]

Projectile B would need more dV to keep the same trajectory as A because the drag on B would be significant.

[Hyperspace Industries]

I read on a university website that deuterium fusion needs 50 million degrees of temperature and 2 atmospheres of pressure. A Farnsworth fusor from the 60's can get 100 million degrees. So, why can't we just pump 2 atmospheres of deuterium in? Unless the reactor is actively reducing the pressure inside it, this should allow for sustained fusion from low power (a Farnsworth fusor can run on mains power).

[Gargamel]

That’s not a reactor, that sounds like a bomb.  

[caecilliusinhorto]

Would it be possible to make a perfectly spherical version of a Prince Rupert's drop in 0g conditions?

[JoeSchmuckatelli]

On 4/5/2022 at 1:47 PM, DDE said:

Mars is still churning a little

https://www.nature.com/articles/s41467-022-29329-x

I read in there that they've discounted any causality from either moon... although I often wonder how seismologists are so certain about this: given that moons can deform liquids on the planet, I'd always assume some sort of magmatic stirring.

2 hours ago, caecilliusinhorto said:

Would it be possible to make a perfectly spherical version of a Prince Rupert's drop in 0g conditions?

Neat question.  I'm not certain of the answer, but I assume the shape has something to do with the tensile properties.

I'd be interested in how you'd go about trying this.  Maybe extrude a blob of liquid glass (to allow it to become spherical) and then 'capture' it in a water container?  Extrude the water around the blob of glass?

(Thing is... I'd not want to do this experiment inside any habitat.  I've seen too many vids of people trying to make Prince Rupert drops with glass shards exploding everywhere on contact with the water.  Likely not good for airway passages or lungs!)

Edited April 9, 2022 by JoeSchmuckatelli

[caecilliusinhorto]

IIRC the shape is only because of gravity, and the tensile properties are because of the way it's cooled.

[darthgently]

48 minutes ago, JoeSchmuckatelli said:

Thing is... I'd not want to do this experiment inside any habitat.  I've seen too many vids of people trying to make Prince Rupert drops with glass shards exploding everywhere on contact with the water.  Likely not good for airway passages or lungs!

Very bad for lungs, but microscopic glass shards couldn't be any good for the air handling/filtering system in general and how would you ever know you ever got it all out?  Definitely something for a dedicated disposable experiment module of a meter cubed or so that can be deorbited later

Edited April 9, 2022 by darthgently

[Shpaget]

21 hours ago, caecilliusinhorto said:

Would it be possible to make a perfectly spherical version of a Prince Rupert's drop in 0g conditions?

I would asume Leidenfrost effect would prevent sufficient contact with water, leading to cooling being too slow.

[SunlitZelkova]

Awhile back I wanted to read more about the concept and Googled “why don’t we launch nuclear reactor waste into space”, however most of the discussions seemed to focus on Earth orbit and the danger of reentry. But why not launch it into solar orbit?

Namely, if it gets to the point where nuclear electric or nuclear thermal rocket space tugs are commuting around deep space (with things like Zeus and DARPA’s recent NTR initiative) and therefore might be economically viable.

[kerbiloid]

https://cen.acs.org/environment/pollution/nuclear-waste-pilesscientists-seek-best/98/i12#:~:text=More than a quarter million,tons in the US alone.

Just a quarter million tonnes of radioactive wastes is accumulated to the date.

I.e. ~250 000 m³, or a cube of 62 m edge. 

So,
1. It's almost nothing to talk about.
2. When the oceanic deuterium fusion powerplants have become a thing, all these wastes will be burnt in neutronic fire for free.

[razark]

3 hours ago, SunlitZelkova said:

“why don’t we launch nuclear reactor waste into space”

Because launch failures are way too common.

[Jacke]

4 hours ago, SunlitZelkova said:

“why don’t we launch nuclear reactor waste into space”

Because launching anything into space is expensive.  And where are you going to send it?  Also, the amount of nuclear waste is small compared to ANY other waste product of our technical society.  It's fairly easy to handle.  And it should actually be reprocessed as it has a lot of nuclear fuel within it.

[wumpus]

4 hours ago, razark said:

Because launch failures are way too common.

Also the stuff you really have to worry about goes away quickly on its own.  It something emits a lot of radiation, each time it emits radiation an atom is decaying into the next (and less energetic) stage.  If something is dangerous *and* has a long half-life, it is because it replaces atoms in your body and emits the radiation entirely inside the body.

I also suspect that at some point fission will become more popular (presumably when it becomes hard to find places for solar panels and windmills) and there is a run on all the spent fuel rods to get that easily obtainable U235.  I'd be curious to see if Jimmy Carter ever regretted his decision on banning reprocessing spent fuel (oddly enough, he was one of the few experts who got a chance to make a call on the political decisions based on technological problems).

[JoeSchmuckatelli]

@K^2 and others deep into the physics / material science spheres:

NTP looks interesting, but apparently only reduces travel time to Mars by 25%.

https://www.energy.gov/ne/articles/6-things-you-should-know-about-nuclear-thermal-propulsion

Are there other papers / info about possible atomic/nuclear rockets that are theoretically practicable but shy of Orion?  Not interested in high ISP low thrust like NERVA but rather solutions to getting significant mass moved quicker. 

(Also looking to leverage your education and experience in cutting through the chaff of crazy but won't work ideas to look at those with potential to succeed in the next 50-70 years or so.)

I've skimmed the wiki and some fairly outlandish sites... But what (in this arena) is worth looking at?

[SunlitZelkova]

8 hours ago, razark said:

Because launch failures are way too common.

I may not have made it clear in the question, but this is supposed to be somewhere in the future where Starship is launching like crazy and costs have come down a bit.

If this is the case, how are we supposed to launch anything nuclear into space? Reactors are planned for Artemis and NTR development has started at DARPA.

8 hours ago, Jacke said:

Because launching anything into space is expensive.

I may not have made it clear in the question, but this is related to the future when launch costs may come down.

8 hours ago, Jacke said:

And where are you going to send it?

As I said-

12 hours ago, SunlitZelkova said:

But why not launch it into solar orbit?