For Questions That Don't Merit Their Own Thread

[darthgently]

35 minutes ago, farmerben said:

Drill four pilot holes.  Then use band saw to connect the holes.  Then use a wedge to crack the back surface and extract a block.

What I've seen, which isn't a lot, but some, to get a good smooth-ish separation there are typically several holes bored down the plane that is to become the crack.  I'm not seeing how to do this easily through the pilot holes or the saw cuts that are normal to that plane.

Unless a typical "gravel" tunnel is bored above and overlapping the "quarry" tunnel with just enough headroom to get some kind of quarrying type rig in above the proposed cut?  So still some gravel waste, but much less?

[magnemoe]

On 8/11/2024 at 3:51 PM, kerbiloid said:

Not actually a question, but a minor invention for space.

1.1. Take a spherical 360 degree glovebox.

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1.2. Cut off the gloves, but leave the cuffs in place.

2.1. Attach a multi-mode shower head on top.

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2.2.  Attach a canister of hand sanitizer.

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2.3. Attach a hairdryer to blow through the shower head.

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3. Attach the extendable space toilet urinal from below.
When it's on, it's making vacuum, so it will be sucking out the spent water from the box and pumping it to other liquid wastes can.

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4. Attach Arduino to switch between the modes:
15 sec =  water with sanitizer
15 sec = clean water
30 sec = warm air

  Reveal hidden contents

 

PROFIT
Now you have a compact zero-g spherical washbasin without any additional equipment but the shower head and the glovebox.

The urinal, the hairdryer, the sanitizer, and the waste collector/processor already present onboard.
You can use them separately or combine in the way described above.

By making a big hole for head in the glovebox, you can also use it to wash hair or pet animals.

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P.S.
Laughing?
Now tell, how will you deliver tons of expendable napkins to the Martian ship during its 3-year long journey.

I put the shower head at the bottom, this way you wash the palms of your hands. Put hand dryer some distance away pipe to bubble, holes with one way valves. And use the vacuum to remove water. 
Let you take off the top so you can use this to put in items to wash
Might simply use an foot or knee switch to cycle, I say you want some remove water time before drying. 
If you stick your head in you need an breathing mask anyway so just make an shower. 

[magnemoe]

double post because of forum bug

Edited August 14 by magnemoe

[magnemoe]

23 hours ago, farmerben said:

Tunneling would be more economical if the spoil was worth good money.  Granite, Basalt, and even limestone blocks and slabs could easily sell for over $1000 ton.  Conventional tunneling makes gravel which is only worth about $30 ton.  A 3300% increase in spoil revenue is huge.  It would financially make up for going slower.

Main problem is that tunnels are not quarries, quarries are put places there the rock is of uniform good quality. Tunnels is put places there you want tunnels. 
Think long wire cutters are most common but you also have cutting blades like giant angle grinder or even giant chain saws for softer rocks. But in the quarries you have access to the rock from top and at least one side so you can cut blocks. 

In an tunnel you have one angle of attack at least until you cut an initial opening. 
Tunnels in rocks is made either by drilling and blasting, repeat or tunnel boring machines, first is best for hard rock or short tunnels later for long or soft stone or just gravel. 
Now I wonder if water cutting jets could be useful, perhaps combined with explosives, drill deeper use an water jet to make an cavity, pump slurry explosives into them and set off.
People has been thinking of weird stuff like using cannons for drilling if tine critical like rescue missions or simply you have to close an major highway or rail line to start drilling so you want the phase to be fast. 

[kerbiloid]

11 hours ago, magnemoe said:

I put the shower head at the bottom, this way you wash the palms of your hands.

A lifehack: usually human joints allow rotate the palms up. Thus the shower head may stay fixed.

11 hours ago, magnemoe said:

Might simply use an foot or knee switch to cycle

A knock with finger and a hit sensor.

11 hours ago, magnemoe said:

And use the vacuum to remove water. 

The space urinal is exactly what's doing it.
So, it can be made double-purpose.

11 hours ago, magnemoe said:

If you stick your head in you need an breathing mask anyway

Not necessary. Some spa procedures implement such head chamber with shower, and I'm a witness, one can easily breath.

[farmerben]

21 hours ago, magnemoe said:

Main problem is that tunnels are not quarries, quarries are put places there the rock is of uniform good quality. Tunnels is put places there you want tunnels. 
Think long wire cutters are most common but you also have cutting blades like giant angle grinder or even giant chain saws for softer rocks. But in the quarries you have access to the rock from top and at least one side so you can cut blocks. 

In an tunnel you have one angle of attack at least until you cut an initial opening. 
Tunnels in rocks is made either by drilling and blasting, repeat or tunnel boring machines, first is best for hard rock or short tunnels later for long or soft stone or just gravel. 
Now I wonder if water cutting jets could be useful, perhaps combined with explosives, drill deeper use an water jet to make an cavity, pump slurry explosives into them and set off.
People has been thinking of weird stuff like using cannons for drilling if tine critical like rescue missions or simply you have to close an major highway or rail line to start drilling so you want the phase to be fast. 

 

[K^2]

I really want an underground bunker, but I'm not allowed to dig here for "earthquake safety reasons." *kicks sand*

[TheSaint]

1 hour ago, K^2 said:

I really want an underground bunker, but I'm not allowed to dig here for "earthquake safety reasons." *kicks sand*

SPECTRE couldn't be defeated by James Bond. But apparently they were undone by building codes....

[kerbiloid]

2 hours ago, K^2 said:

I really want an underground bunker, but I'm not allowed to dig here for "earthquake safety reasons." *kicks sand*

No need to dig.

Google, images, "winkel tower".

Spoiler

 

[farmerben]

Would carbon monoxide be the ideal fuel for a Mars direct style ISRU fuel system? 

It gets and ISP of only 200s.  So its half as powerful as methane or kerosene.  But you only need 1/9 of the dV to go from surface to orbit.  

The real question is can you the machinery to make carbon monoxide out of CO2 and separate the oxygen as well be made in a compact lightweight form?

You can also blend gaseous fuels (possibly).  Wood gas is about half carbon monoxide and half hydrogen.

Edited August 19 by farmerben

[magnemoe]

10 hours ago, farmerben said:

Would carbon monoxide be the ideal fuel for a Mars direct style ISRU fuel system? 

It gets and ISP of only 200s.  So its half as powerful as methane or kerosene.  But you only need 1/9 of the dV to go from surface to orbit.  

The real question is can you the machinery to make carbon monoxide out of CO2 and separate the oxygen as well be made in a compact lightweight form?

You can also blend gaseous fuels (possibly).  Wood gas is about half carbon monoxide and half hydrogen.

CO has the major benefit that you don't need water so you can just generate it out of Mars atmosphere, you still need plenty of power and no idea how small you can make this. Pretty pointless for sample return as if you have an return capsule in mars orbit you only need something the size of an anti tank missile to launch it. 

[DDE]

14 hours ago, farmerben said:

Would carbon monoxide be the ideal fuel for a Mars direct style ISRU fuel system? 

It gets and ISP of only 200s.  So its half as powerful as methane or kerosene.  But you only need 1/9 of the dV to go from surface to orbit.  

The real question is can you the machinery to make carbon monoxide out of CO2 and separate the oxygen as well be made in a compact lightweight form?

You can also blend gaseous fuels (possibly).  Wood gas is about half carbon monoxide and half hydrogen.

Immediately before Mars Direct, Zubrin & co worked on a CO2 nuclear thermal rocket instead.

Edited August 20 by DDE

[K^2]

6 hours ago, DDE said:

Immediately before Mars Direct, Zubrin & co worked on a CO2 nuclear thermal rocket instead.

Not a bad concept, but CO2 kind of sucks to store. You need a bit over 5 bar in a tank to keep it liquid even at cryogenic temperatures. It's not a huge pressure, but it's more than you typically want in a tank, so it is going to contribute to the weight. You can freeze it solid, obviously, but then getting it out of the tank in a controlled manner becomes a bit problematic. (Solid fuel NTR with radiative heat transfer from core to the fuel is a thought, but that would require a very uniform chunk of ice, so I don't think it's an ISRU kind of idea.)

So I'm kind of looking back at carbon monoxide now. That'll sit liquid at 1 bar and 81K. Much lighter tank, enough pressure to feed it into the tank with just boil-off, and you'll get better I_SP with NTR that way. Oxygen is now a byproduct, and not something you have to hoard for ascent, so you can potentially store it for manned missions (assuming this is like a cargo shuttle or w/e) and you want your nuclear reactor to be able to produce power to condense CO2 out of atmo anyways, so splitting it down to CO doesn't seem like that much overhead.

A CO NTR might be the best ISRU cargo shuttle we can reasonably design with tested tech.

[farmerben]

What is the best propulsion method to perturb a comet so it will impact Mars?

[Terwin]

19 minutes ago, farmerben said:

What is the best propulsion method to perturb a comet so it will impact Mars?

Depends on how big a comet you want and how patient you are.

If you are willing to wait a century for a small comet, an ion drive could work, if you need something large within a decade you would probably need Orion.

 

[darthgently]

22 minutes ago, farmerben said:

What is the best propulsion method to perturb a comet so it will impact Mars?

Timing of the propulsion event would be as critical as the type of propulsion for the same reasons that when and where a maneuver node is placed on an orbital path can make a huge difference in the scale of effect.

Ideally one could leverage gravity assists from other bodies as well.  Perhaps if we launch the entire terran nuke arsenal at the next comet to come near Earth we could get an Oberth-Nuke effect perturbation.  But seriously, same as rocket, we'd want to change the comet's AP at PE and vice versa and do plane changes at the relative node of the planes involved.  So whatever propulsion technique would need to be able to be applied from a variety of thrust vectors and all around the orbit.  For this reason I rule out big ablative beams from Earth SOI doing effective steering.  Better to have something local and traveling with the comet. 

Like a huge Orion drive that can push it from any direction by approaching it along the desired thrust vector, making contact, then boom-boom-boom...

Then it is just a matter of a few millennia 

[farmerben]

I think you need to use the comet itself as propellant.

[DDE]

58 minutes ago, farmerben said:

I think you need to use the comet itself as propellant.

Mass drivers with reusable buckets, then. They don't care what's in the remass. Otherwise you'll run out of water filters pretty quick.

Edited August 21 by DDE

[K^2]

1 hour ago, farmerben said:

I think you need to use the comet itself as propellant.

Which you might be able to achieve by strategically painting the comet.

[AckSed]

7 hours ago, DDE said:

Mass drivers with reusable buckets, then. They don't care what's in the remass. Otherwise you'll run out of water filters pretty quick.

One of the single-player campaigns of the space exploitation boardgame High Frontier is Hermes Fall, where you have to build a factory with a robonaut, power source and a mass driver on a binary asteroid to deflect them before they hit the Earth in 24 years. It is nearly impossible because it models the rocket equation and the solar cycle, you're starting from nothing but your inefficient launch vehicle and carting out two full stacks to the asteroid belt takes a lot of fuel.

[farmerben]

The scenario of deflecting a comet so it misses a planet is very different than deflecting one so it hits.

You want to do most of the pushing way out in Kuiper belt where velocity is slow.  You have to maneuver the comet very precisely.  So I think you need to land on the comet and have variable thrusters.  Nuking it is not precise enough.  The painting strategy might not be precise enough either.

 

[darthgently]

3 hours ago, farmerben said:

The scenario of deflecting a comet so it misses a planet is very different than deflecting one so it hits.

You want to do most of the pushing way out in Kuiper belt where velocity is slow.  You have to maneuver the comet very precisely.  So I think you need to land on the comet and have variable thrusters.  Nuking it is not precise enough.  The painting strategy might not be precise enough either.

 

If the relative plane AN/DN.  is near AP this would be ideal.  One could match planes (closer anyway) and adjust the orbit on a budget in one burn.  It would take many repeated burns even then with near hundreds of years between burns

Edited August 22 by darthgently

[farmerben]

Most of the objects we are interested in have periapsis at the range of Pluto and beyond, namely balls of frozen water and ammonia which will help build an atmosphere on Mars.  We should be able to find plenty of Kuiper belt objects with the inclination close to ideal already.  4000-5000 km/s of delta V should be more than adequate.

If you had a mass driver you might be better off flinging snowballs at mars thousands of times and letting the main comet go into interstellar space.  This would allow you to adjust your aim.  And if some of your shots miss by 1000 years it will not be bad for the Martians as small ice chunks will "burn up" in the atmosphere, where a giant comet might not.

 

[kerbiloid]

A swarm of low-solar-orbit lasers, focused at the huge mirror in front of the comet, reflecting the beams to vaporise the comet matter, and  thus retropush it towards the Mars orbit.

The best place to produce the swarm is the Mars, due to lot of metals and volatile fluids at once, together with low launch and transfer delta-V.

[kerbiloid]

If the entropy is always growing, how can the Universe expansion be determinate?