For Questions That Don't Merit Their Own Thread

[DDE]

1 minute ago, Kerwood Floyd said:

Well, that's because no subs can do much more than that. All this nonsense about submarines being able to go 100s of meters down is just a huge lie the naval powers of the world have been telling us for over a century now. It obviously just isn't possible.

 

(This is my personal version of 'the moon landings were faked', 'the earth is flat', 'birds aren't real', etc.)

To be fair, there's been a lot of misinterpretations. Both sides of the Cold War suspected the other had subs that go below 400 m out to 1000 m. The only boat actually confirmed to have done so caught fire and sunk.

[Kerwood Floyd]

2 minutes ago, DDE said:

To be fair, there's been a lot of misinterpretations. Both sides of the Cold War suspected the other had subs that go below 400 m out to 1000 m. The only boat actually confirmed to have done so caught fire and sunk.

To be fair, I'm exaggerating for the sake of my parody of nut-ball conspiracy theorists. 

[kerbiloid]

Nautilus has submerged to the 16 km depth.

http://www.westernexplorers.us/Jules_Vernes_submarine_Nautilus.pdf

And that's by the XIX century technologies.

Jules Verne is a witness.

[Hyperspace Industries]

2 hours ago, Gargamel said:

Stump remover (Potassium Nitrate?) and Sugar?   Those should be available.    I'd stick with solid fuels until you get very very comfortable machining metal parts that can handle liquids.

Unfortunately not, they're not available anywhere over here, and believe me, I've looked.

(Except maybe for some specialized fertilizers, which I can pretty much only get by spending quite a bit buying them online. I could probably afford it but I hate spending money. (I'm what we call "seinig" which apparently translates to frugal.))

Edited March 30, 2022 by Hyperspace Industries

[magnemoe]

On 3/29/2022 at 4:43 PM, JoeSchmuckatelli said:

Somewhere in the middle to right up there.

I'd be surprised if they're not already working on low tech winged drones.  I suspect the copter type drones don't have the lift for the cost of effort; i.e. not enough product shipped vs cost, time and exposure.

What's more likely to happen is a towed-launched wooden or composite 'throw-away' glider type drone that they hope has a low cross section and can be landed with relative accuracy at night.  Given the money we're talking about and the proliferation of off-the-shelf quality optics, that should be pretty easy to acquire.  That's both relatively low cost and relatively low exposure.

Except that once we start finding abandoned drones littering California to Texas... they'll get themselves above the 'irritant' threshold.  The thing is - even a wooden drone is detectable on modern radars; the algorithms alone can spot a moving 'lack of reflection' just as easily as old radars pinged off of moving metal.  So having the military / Homeland increase border surveillance  will result in loss of product and useful mules - and possibly trigger counter-ops in-country to locate and reduce the manufacture / base of these drones.

 

(Heck - there's your story, right there!)

No an lack of reflection is the same as air does and is not detectable, that you detect is the plane launching them. The drone will also has some refection from various metal parts. 
Yes it would have low radar silhouette for its size but is something you could pick up if you locked an targeting radar on the drop plane. 
Then you follow it to it land and looks for some who will collect the cargo, now you could drop the cargo before landing, this would make this countermeasure much harder. 

Wonder if just using an drone with an engine would work just as well here, it can be reused and its no plane involved, if you identify the plane the pilot would be in problems. 
That if if you converting something like an old Cessna to an drone. Take off cross the border drop the payload, fly back over the border and land at another location for recovery. 

 

[JoeSchmuckatelli]

55 minutes ago, magnemoe said:

lack of reflection is the same as air

It's not detecting a lack of reflection, remember it's not invisible; the light (EMR) doesn't pass through the object as if it were not there - the geometry scatters and the coatings absorb.  So with sufficient fidelity and high speed computing what you can get is something moving that isn't identical to the static background... and that is trackable.

There's also the issue of how the 'stealth' is designed; is it for high frequency, high fidelity military radars (and especially tracking/guidance systems)?  Or is it lower frequency radars like civil aviation?  There's some literature that the latter can actually track fighter sized 'stealth' aircraft - even if the fidelity isn't enough to synch it up with a radar guided SAM.

FYI:

Is China Capable of Tracking and Shooting Down the F-22 Raptor? | The National Interest

Edited March 30, 2022 by JoeSchmuckatelli

[kerbiloid]

Afair, in 1990s Gulf War F-117 was operating together with a dozen of F-15.

A cloud of the  non-stealths is the best stealth's friend.

[SOXBLOX]

3 hours ago, kerbiloid said:

Afair, in 1990s Gulf War F-117 was operating together with a dozen of F-15.

A cloud of the  non-stealths is the best stealth's friend.

There's a reason, though, that the F-117 did like 80% of strike missions. Stealth is just that hard to beat.

[SunlitZelkova]

11 hours ago, Gargamel said:

3rd thought...    Wait... there's been tracked rovers before right?   How'd those work out?

There was at least one proposal for Mars- http://spaceflighthistory.blogspot.com/2017/08/prelude-to-mars-sample-return-mars-1984.html None I am aware of for the Moon, either crewed or uncrewed.

Otherwise, no, there have not been. I kind of wonder if that is because wheels are better in some way, or if it is because people prefer to work off of the known data from the Apollo LRV, Lunokhod, and all of the Mars rovers instead of trying something completely new.

[StrandedonEarth]

23 hours ago, JoeSchmuckatelli said:

 

If we could land a bull dozer size and mass and power 'work-rover' on the Moon or Mars, would we use the 6-wheel system of current rovers or tracks like current bulldozers? 

 

IIRC, the main function of tracks is to spread the weight out over soft (muddy) ground, no? They are also “run flat” since there is no air to lose, which is probably why they were favoured for military tanks, at least until non-pneumatic wheel tech advanced more. There are plenty of wheeled excavators out there too, probably partly because (steel) tracks  like to tear up pavement. Although I have seen tracks with rubber cleats, presumably to prevent excessive road damage. So I think it’s likely they’ll stick with wheels; they could use planks or oversized “balloon” tires if they discover any soft “ground”. 

That said, some sort of work vehicle will probably be needed to create berms and bury habitats. I expect it to be challenging because the low gravity will severely reduce how much pushing force can be generated before losing traction. 

[JoeSchmuckatelli]

27 minutes ago, StrandedonEarth said:

the low gravity will severely reduce how much pushing force can be generated before losing traction. 

That's what I've been pondering.  Dozers can push 7 to 10 thousand pounds (based on blade strength) - but at 1g they've got plenty of... Mule-Daddy ...behind them to do the work.  I'm guessing that given the weight difference on a different body they'd be able to push similar yardage - but not cut like they can here.

So the loose stuff and maybe soil-analogs will move, but buried boulders might need an excavator (which pulls down, generally, so I'm confident they'd work).

But as @Gargamel brought up - what I don't know is whether the complexity or problems with cold-welding might mitigate against a tracked vehicle, despite the advantages they have on soft/loose dirt.

 

 

 

 

 

(Interesting side note: aside from Regolith - I don't know any word like 'dirt' that doesn't scream 'life'.  Sand - isn't dirt; and also doesn't support life well, but soil, earth, dirt, etc. are all permeated with life - and most terrestrial sand and dust still contains a healthy volume of organic matter.  Regolith just sounds like shattered rocks on a moon, but what do we call dirt-analogs on planets with atmospheres when we don't know if they contain organics?).

Edited March 31, 2022 by JoeSchmuckatelli

[Gargamel]

Sand is dry dirt

Dirt is slightly moist..... dirt. 
Mud is wet dirt. 
Soil is dirt with organics.  
Regolith is (possibly spherical) dirt in a vacuum.    

Edited March 31, 2022 by Gargamel

[Gargamel]

Huh.... looking up the definition of dirt.... it may be one of the few words that is actually best defined using the word itself.    Dirt is the stuff on the ground that makes you dirty.  It’s just....dirt.  
 

 

[kerbiloid]

7 hours ago, SOXBLOX said:

Stealth is just that hard to beat.

I guess, the cloud of fighters guarding that stealth, would allow do the same for any other plane as well.

It's much easier for a thief to snick into the house through the back window when a dozen of bandits are crashing the doors with sledgehammers, but it looks like they didn't need the thief very much to get in.

5 hours ago, SunlitZelkova said:

There was at least one proposal for Mars- http://spaceflighthistory.blogspot.com/2017/08/prelude-to-mars-sample-return-mars-1984.html 

All these people are thanking the Martian gods for they don't have to do this in spacesuits.

Spoiler

And remember, a track has by orders of magnitude more joints than a simple wheel, and both Mars and Moon are nasty dusty.

***

Just a side note.
The Mars-3 walking probe.

Spoiler

https://en.wikipedia.org/wiki/PrOP-M

 

 

Make it bigger for heavy tech like harvesters. Use wheels for lunar trucks and pickups.

Build concrete roads and areas for the lunar base. Hide the base underground and cover the pits with panels.

[JoeSchmuckatelli]

23 minutes ago, Gargamel said:

Huh.... looking up the definition of dirt.... it may be one of the few words that is actually best defined using the word itself.    Dirt is the stuff on the ground that makes you dirty.  It’s just....dirt.  
 

 

Yep... commonly.

Quote

Soil is also commonly referred to as earth or dirt; some scientific definitions distinguish dirt from soil by restricting the former term specifically to displaced soil.

Soil - Wikipedia

also

Quote

If you were to divide a soil sample into 20 parts, 9 parts would be made up of the stuff we think of as dirt: clay, silt and sand. These are inorganic particles, which means they come from non-living sources. A full half, or 10 parts, would be equally divided between air and water. The last part would be organic, made from dead and decaying organisms. The soil also would contain countless numbers of minuscule microbes, mostly fungi and bacteria.

The dirt on soil | Science News for Students

But - there is a connotation (at least in English) that lends the essence of such a thing as 'dirt' as being a place we can plant something and it will grow.  Yeah, sure, such dirt is actually soil... but again to the commonality; we think stuff grows in dirt - and those of us who think on these thinks know that life feeds on life - thus 'dirt' must in some form have life in it to support life.

Even rocks can be 'et' by lichens!

So what, then, is lifeless dirt?  Is it - still - 'dirt'?

3 minutes ago, kerbiloid said:

And remember

FWIW - I've lived the picture above this quote.

Fun times!

Edited March 31, 2022 by JoeSchmuckatelli

[kerbiloid]

Another side note about the landers and rovers.

In any case a heavy lunar/martian rover absolutely needs the outriggers to let the wheels have a rest between movements.
You don't have a wheel shop there, and the simple pistons are stronger and more reliable than wheels or tracks.

Though, rarely we can see them in sci-fi designs.

***

As the chassis part of the rover will get damaged much faster than its functional part, a rover may have the chassis as a separate part, to be delivered without the whole rover replacement.

This in turn means some bridge workshop to lift the upper and replace the lower.

This in turn means that the chassis type may be switched in the rover's lifetime.

***

A heavy landing spaceship (a Nexus or a Prometheus/Rocinante) should have even three types of gears:

1) Landing gear. For soft landing. To be  retracted under the landing process.
2) Parking gear. The outriggers. To stand.
3) Motion gear. Wheels, stepping platforms, or tracks. To be extended (from the ship) or temporarily attached (to the Nexus, or planetary base modules), when you need to move it from the random landing position to the service pad, launch pad, or to another landed ship to dock them.

***

The Rocinante-like ships should dock with side extendable docking ports of a railroad tunnel size, with extendable rails connecting inside to move cargo.

Edited March 31, 2022 by kerbiloid

[JoeSchmuckatelli]

21 minutes ago, kerbiloid said:

The Rocinante

I still haven't finished the series - but, tbh, I can't look at the Roci (and its capabilities) without wanting one.

Me likey!

[SOXBLOX]

7 hours ago, kerbiloid said:

I guess, the cloud of fighters guarding that stealth, would allow do the same for any other plane as well.

There were no clouds of fighters guarding the F-117. It flew solo strike missions into the heaviest air defense umbrellas. In many cases, other strike packages would be present in the same general area, coming in from different directions. Maybe that confused you?

Edited March 31, 2022 by SOXBLOX

[kerbiloid]

27 minutes ago, SOXBLOX said:

There were no clouds of fighters guarding the F-117. It flew solo strike missions into the heaviest air defense umbrellas. In many cases, other strike packages would be present in the same general area, coming in from different directions. Maybe that confused you?

Idk personally, I read that in "Foreign Military Review".

[JoeSchmuckatelli]

Waaay back in the day, the original BattleStar Galactica had a scene where one of the ships (in deep interstellar space} picked up a television broadcast - IIRC the moon landing or some such. 

How likely would that be? 

Do our incessant emissions in the TV and Radio sphere have enough fidelity to be picked up 70 ly away given the giant yellow ball of static currently warming half the planet? 

[SOXBLOX]

4 minutes ago, JoeSchmuckatelli said:

Waaay back in the day, the original BattleStar Galactica had a scene where one of the ships (in deep interstellar space} picked up a television broadcast - IIRC the moon landing or some such. 

How likely would that be? 

Do our incessant emissions in the TV and Radio sphere have enough fidelity to be picked up 70 ly away given the giant yellow ball of static currently warming half the planet? 

Ehhh... Maybe a teeny tiny bit.

But what they'd really notice would be the early warning radars. Clear AFB, Thule, and Olenegorsk would look like beacons compared to wimpy TV signals. 

[kerbiloid]

They warn the aliens about us.

[JoeSchmuckatelli]

7 hours ago, kerbiloid said:

They warn the aliens about us.

IIRC Spider Robinson wrote a story about this 

[GearsNSuch]

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. 

[magnemoe]

On 3/30/2022 at 6:33 PM, JoeSchmuckatelli said:

It's not detecting a lack of reflection, remember it's not invisible; the light (EMR) doesn't pass through the object as if it were not there - the geometry scatters and the coatings absorb.  So with sufficient fidelity and high speed computing what you can get is something moving that isn't identical to the static background... and that is trackable.

There's also the issue of how the 'stealth' is designed; is it for high frequency, high fidelity military radars (and especially tracking/guidance systems)?  Or is it lower frequency radars like civil aviation?  There's some literature that the latter can actually track fighter sized 'stealth' aircraft - even if the fidelity isn't enough to synch it up with a radar guided SAM.

FYI:

Is China Capable of Tracking and Shooting Down the F-22 Raptor? | The National Interest

This is correct stealth is optimized for high frequency radar who the military prefer is its more accurate and you can use smaller radars or have more elements in an phased array. 
You can use longer frequency, traffic control mostly use transducers but they have radars too. 
Downside is that you can not put an low frequency radar in an missile or fighter jet, but if you locate something you can then hit it with an high power targeting radar or in worse case send an fighter after it.