Big Water On Mars!

[Vertigo]

And a mass driver could also be used to land supply ships, so you don't necessarily need rocket propellant to land.

As far as I'm aware mass drivers could be used for launches but not for landings.

 

[Onyx]

I presume you're not seriously suggesting the next Moonbase would be little more than a few tents?

As I mentioned earlier, if you already have a structure (lava tube) that provides radiation protection and some insulation, the main thing you need to convert that space to a habitat is to make it airtight and regulate the temperature. Call it a "tent", inner tube, airtight lining, whatever you want. But nature already provided walls, ceiling and floor.

In other words - if the Moon wasn't anything like the Moon and more like Earth?

Since the comparison is between the moon and ISS, I'd say a lava tube on the moon is considerably more like the earth than ISS is. Gravity, fewer space restrictions, more radiation protection, etc. So astronauts may be physically and mentally better able to withstand life there from much longer periods than the cramped zero G, higher radiation ISS environment.

And thinking more about the gravity problem, a simple way to "train" while living on the moon is to wear an enormously heavy vest to load the muscles and skeleton like they would be on earth. A 200kg led vest would make it feel like you were standing in earth gravity.

You're going to need something to control any landing, though. I'm curious, though - do you see mass drivers as replacing launch vehicles to the ISS?

Not unless the earth suddenly loses the 100km of atmosphere that any sort of ballistic launch system would have to contend with, or the gravitational pull of the earth dropped to something lower than the moon's:

"Mass driver" is a term for a ballistic launch device, usually one that works magnetically, but it could also be something like a cannon. For a mass driver to work on earth with no atmosphere, the launch velocity would have to be mach 33. With an atmosphere it would have to be mach 33 plus whatever extra velocity is required to make up for the velocity loss due to air drag, which is considerable at mach 33.

And just to make this obvious - mach 33, or thirty three times the speed of sound - is not a speed that anything we could make could withstand the air friction. It would simply burn up as soon as it exited the evacuated barrel of the driver.

In contrast, the moon has 1/6 earth gravity and no atmosphere. So its escape velocity is only mach 7, or 8568 kph. Which isn't really much of a problem when you don't have an atmosphere.

If you wanted to build a mass driver that would accelerate a manned capsule up to lunar escape velocity at no more than 9Gs, it would have to 32 kilometers long. But if you planned to use any fuel, then whatever velocity the driver gave you would add to the stored delta vee in the rocket fuel. Or you could use a shorter, higher G driver and put the passengers in a water bath to mitigate the acceleration. Of course, a US Air Force officer once endured 46 Gs for a few seconds without being buoyant.

 

[Onyx]

As far as I'm aware mass drivers could be used for launches but not for landings.

You would need to have a landing craft that would strip velocity off fired slugs magnetically to scrub its inbound velocity. Once its velocity is low enough, the driver could toss it a locally made landing booster (aluminum and oxygen motor).

Or, the incoming ship simply falls into the barrel of the gun and decelerates in the opposite way of the launches.

 

[Vertigo]

You would need to have a landing craft that would strip velocity off fired slugs magnetically to scrub its inbound velocity. Once its velocity is low enough, the driver could toss it a locally made landing booster (aluminum and oxygen motor).

Or, the incoming ship simply falls into the barrel of the gun and decelerates in the opposite way of the launches.

Sorry I don't really see either of those as practical. For the first part you'd have had to lift all of those slugs in the first place in order to throw them away later, and capturing them for reuse would use as much fuel as you saved in the first place. Fuel seems simpler and more effective.

For the second considering the speeds that would be involved the slightest fault/wobble/misjudgement in the system and you have a major disaster on your hands.

 

[Onyx]

For the first part you'd have had to lift all of those slugs in the first place in order to throw them away later, and capturing them for reuse would use as much fuel as you saved in the first place. Fuel seems simpler and more effective.

You could manufacture the slugs on the moon. They don't have to be iron - you could induce a magnetic field in aluminum wiring wrapped around moon rock. If they are fired at just over escape velocity, they will fall back to the moon once a significant amount of their velocity has been transferred to the incoming ship. Or, they can cargo bound for somewhere else.

For the second considering the speeds that would be involved the slightest fault/wobble/misjudgement in the system and you have a major disaster on your hands.

That really just sounds like a lack of faith in technology. There are no crosswinds in space. If the ship is aligned 10,000 kilometers out will remain aligned from there on. Aligning the ship and the open magnetic driver lattice isn't any more difficult than aligning the docking rings on 1970s spacecraft.

Also, the mass driver doesn't have to be a tightly fitted barrel. It will take more electricity, but it could be much larger in inner diameter than the incoming ship. And the magnetic system of the driver would pull against the ship asymmetrically as needed to keep it aligned with the curvature of the moon's surface. If there was a failure the lattice could pop open and the ship would continue in a straight line away from the moon's surface.

A lot of things that seem difficult become simpler when you aren't dealing with atmospheres. You could orbit a satellite a few inches above the highest point on the moons equator if you wanted to. With the right sort of pre-planning a regular system of rising and falling masses around the moon could allow a lot of things to happen without more than steering propellant.

 

[Brian G Turner]

That really just sounds like a lack of faith in technology.

Sounds like realism to me.

 

[Robert Zwilling]

If people go to the Moon with the idea that they will be staying there for a long time to cut down on costs, that would put a lot of pressure on the infrastructure to immediately perform as planned.

Can the effects of low gravity be offset by working out in a gym 2 hours a day. If the floors were magnetic, would walking around in magnetic boots provide a good workout?

If geological features could be sealed up cheaply, that could offer some savings on the cost. Seems like the Mayflower experience could be up for a reboot. Ironically in the land of plenty, the Mayflower colonists couldn't find anything to put on the return ship trips, they were too busy trying to survive. If you spend over 60 percent of your time trying to survive I don't think you can get much accomplished. Besides low gravity manufactured products are there any known items that could be brought back from the Moon to help offset the costs? Could there be gem pockets on the Moon worth enough to spend time looking for them.

 

[Onyx]

Sounds like realism to me.

Landing a rocket on earth vertically takes much greater precision and control than getting two inert bodies in space to line up with each other. But no one is claiming that SpaceX's vertical landing rockets are doomed. A Patriot missile is working much harder when it cuts through the cockpit of an evading fighter jet at mach 4, and they do that very reliably.

At some point we're going to have to do this sort of trick fairly often if we want to move things around the solar system without constantly mining everything for propellant.

 

[Onyx]

If the floors were magnetic, would walking around in magnetic boots provide a good workout?

Not really, they would just get a little workout from pulling their feet free. But putting weight on their shoulders would work their body from neck to feet.

If you spend over 60 percent of your time trying to survive I don't think you can get much accomplished. Besides low gravity manufactured products are there any known items that could be brought back from the Moon to help offset the costs? Could there be gem pockets on the Moon worth enough to spend time looking for them.

No one on the moon is going to be spending all their time learning to hunt turkey and deer. There would be a struggle to get the aquaculture or whatever kind of farming set up, but the main occupation would be assembling automated refineries to extract aluminum, silicon, oxygen and iron out of the soil, plus water ice and smaller amounts of CO2, methane and ammonia. All of that would be useful for the construction of near earth space stations and ships to go to other places in the solar system.

There has long been an assumption that the best way of getting large projects done in space is by capturing an asteroid to mine. But the moon is a big mineable asteroid we already have, and it looks like it has some structures built in that would make it easier to get labor in place than anywhere else in the solar system.

 

[Brian G Turner]

Landing a rocket on earth vertically takes much greater precision and control than getting two inert bodies in space to line up with each other. But no one is claiming that SpaceX's vertical landing rockets are doomed.

I'd love to share your optimism that just because the Moon is a less complicated place to launch from means accidents are less likely - but that doesn't make the process necessarily safe, especially considering that even modern rocket launches are prone to fail explosively: Rocket developed by Japan startup in flames after liftoff

Even the robust Ariane 5 rocket has a 5% failure rate: Ariane 5 - Wikipedia

Setting up all the necessary equipment on the Moon is bound to be challenging at the best of times, and any system that might be completed may introduces its own degrees of error.

And thinking more about the gravity problem, a simple way to "train" while living on the moon is to wear an enormously heavy vest to load the muscles and skeleton like they would be on earth. A 200kg led vest would make it feel like you were standing in earth gravity.

That wouldn't negate the problems of weightlessness on human biology, though. I linked through to a good piece on space surgery than ran through some of the problems - it's not just about muscle wastage and bone loss: https://onlinelibrary.wiley.com/doi/full/10.1002/bjs.10908

In the meantime, I think we were discussing water on Mars.

 

[Onyx]

I'd love to share your optimism that just because the Moon is a less complicated place to launch from means accidents are less likely - but that doesn't make the process necessarily safe, especially considering that even modern rocket launches are prone to fail explosively: Rocket developed by Japan startup in flames after liftoff

Even the robust Ariane 5 rocket has a 5% failure rate: Ariane 5 - Wikipedia

Setting up all the necessary equipment on the Moon is bound to be challenging at the best of times, and any system that might be completed may introduces its own degrees of error.



That wouldn't negate the problems of weightlessness on human biology, though. I linked through to a good piece on space surgery than ran through some of the problems - it's not just about muscle wastage and bone loss: https://onlinelibrary.wiley.com/doi/full/10.1002/bjs.10908

In the meantime, I think we were discussing water on Mars.

Moon gravity and Mars gravity isn't microgravity. We don't really know how little gravity it takes to maintain healthy fluid distribution in the body. Is 1/6 too little by 1/3 enough?

But the mass catcher I was talking about isn't a rocket and wouldn't suffer the kind of failures chemical rocket motors can. It is more analogous to getting a bearingless electric motor to work correctly - it is a control problem. Just because the closure rate is high that doesn't mean that the degree of control isn't also high while the factors causing error are relatively few. Space is a very controlled environment - the Russians figured out how to place a small satellite in a stable orbit for 3 months using an ICBM in the 1950s. Putting a missile through a hoop on the moon with no atmosphere and multiple ways of checking and controlling alignment should be a relatively simple task - little different than a laser guided bomb.

Sorry about Martian water.

 

[Brian G Turner]

And on-topic about terraforming Mars - apparently there's not enough CO2 to make that possible at the moment: Terraforming Mars might be impossible due to a lack of carbon dioxide

Right now Mars has an atmospheric pressure of about six millibars – tiny compared to the one bar at sea level on Earth. ... At one bar, the temperature would be just above 0°C, allowing liquid water, and thus life, on the surface.

...

But Jakosky and Edwards found that there’s probably only enough carbon dioxide in the Martian polar ice caps, dust and rocks to raise the pressure to 20 millibars at most. So we can’t terraform Mars with existing technology, because there simply isn’t enough carbon dioxide. “It’s not that terraforming itself isn’t possible, it’s just that it’s not as easy as some people are currently saying,” says Jakosky. “We can’t just explode a few nukes over the ice caps.”

 

[Robert Zwilling]

Still off course here, since there isn't enough carbon dioxide on Mars, would carbon be valuable enough to make it practical to export carbon from Earth? If it was exported what would be the best form of it. There is carbon in asteroids but anything of size are few and far between. Would there be more value in collecting the dust than the same effort expended flying around to gather up asteroids of any size?

 

[Robert Zwilling]

Underground water deposits on Mars could contain contain oxygen

Underground Martian water deposits might have plenty of oxygen in them.
Microbial life on Mars is back on the front pages again. It is surmised it would be under the surface where it would be protected and it's resources would also be protected by a thick covering of the upper surface. There could be a reservoir of readily accessible oxygen for microbial life dissolved in a brine solution. I think more likely what is growing under the surface is microbial but not necessarily oxygen based. The physical components of microbial life works in a way similar to mechanical fashion and can use different fuels to to achieve the same results. There is plenty of stuff here on Earth that isn't oxygen or sunlight based and survives perfectly fine. They are called extremophiles, meaning living in extreme conditions compared to normal Earth life. It wouldn't be unlikely if oxygen based life was the extremophile life for for the rest of the solar system, or even the galaxy, and all the stuff we call extreme is the majority format for life in general.

Life on Mars, having evolved under such conditions and knowing that there are organisms that can "eat" metal and plastic on Earth, it might not be unlikely that spacesuits would be on the Martian microbes menus as a tasty after dinner treat.

 

[BAYLOR]

Underground water deposits on Mars could contain contain oxygen

Underground Martian water deposits might have plenty of oxygen in them.
Microbial life on Mars is back on the front pages again. It is surmised it would be under the surface where it would be protected and it's resources would also be protected by a thick covering of the upper surface. There could be a reservoir of readily accessible oxygen for microbial life dissolved in a brine solution. I think more likely what is growing under the surface is microbial but not necessarily oxygen based. The physical components of microbial life works in a way similar to mechanical fashion and can use different fuels to to achieve the same results. There is plenty of stuff here on Earth that isn't oxygen or sunlight based and survives perfectly fine. They are called extremophiles, meaning living in extreme conditions compared to normal Earth life. It wouldn't be unlikely if oxygen based life was the extremophile life for for the rest of the solar system, or even the galaxy, and all the stuff we call extreme is the majority format for life in general.

Life on Mars, having evolved under such conditions and knowing that there are organisms that can "eat" metal and plastic on Earth, it might not be unlikely that spacesuits would be on the Martian microbes menus as a tasty after dinner treat.

Life has a tendency to find a way to survive in harsh conditions.

 

[Robert Zwilling]

I always think of Jurassic Park when Life has a tendency to survive in harsh conditions.