Near-future Expansion of Human Presence in Cislunar Space

[LMT]

this is assuming that profitable deposits of gold can be found in the near-term on the surface of Mars

Given Mars' E-belt impact-capture conditions,

and the nuclear spectroscopy that maps ore groupings from orbit,

the survey suggests itself.

But those are Mars posts, and this is cislunar.

[LMT]

I don't think we on the outside know what engineering aspect that sets the return cargo limit on Starship, or if they will be able to bring 50 tonnes of cargo from Mars, not just from LEO, down to Earth.

A Starship can aerocapture, e.g., to LEO; then EDL. 

Logically, that would be 50 tons delivered from beyond LEO, with no difference in "engineering aspects".

--

Many express doubts about 50 ton return, often just when multi-billion-dollar value is affixed. 

The reasoning is unsound, as we see above, and upthread, and elsewhere.  And it often appears just when there's significant commercial value.

I think it raises sociological questions, likely not allowed here.

[Owlon]

I don't think we on the outside know what engineering aspect that sets the return cargo limit on Starship, or if they will be able to bring 50 tonnes of cargo from Mars, not just from LEO, down to Earth.

A Starship can aerocapture, e.g., to LEO; then EDL. 

Logically, that would be 50 tons delivered from beyond LEO, with no difference in "engineering aspects".

--

Many express doubts about 50 ton return, often just when multi-billion-dollar value is affixed. 

The reasoning is unsound, as we see above, and upthread, and elsewhere.  And it often appears just when there's significant commercial value.

I think it raises sociological questions, likely not allowed here.

I doubt many people question the 50 ton landing capability in general. I suspect the question is more in the corner of whether Starship has the delta-V to launch from Mars surface direct to Earth with 50 tons of cargo. It could certainly be done with refueling in LMO, but that might be logistically difficult early on. Payload return shouldn't be a problem in cislunar space, as it wouldn't be a huge leap to refuel an arbitrary number of times on the Moon-to-Earth journey, just like you would refuel in LEO and maybe somewhere in lunar orbit on the way there.

[LMT]

I don't think we on the outside know what engineering aspect that sets the return cargo limit on Starship, or if they will be able to bring 50 tonnes of cargo from Mars, not just from LEO, down to Earth.

A Starship can aerocapture, e.g., to LEO; then EDL. 

Logically, that would be 50 tons delivered from beyond LEO, with no difference in "engineering aspects".

--

Many express doubts about 50 ton return, often just when multi-billion-dollar value is affixed. 

The reasoning is unsound, as we see above, and upthread, and elsewhere.  And it often appears just when there's significant commercial value.

I think it raises sociological questions, likely not allowed here.

I doubt many people question the 50 ton landing capability in general. I suspect the question is more in the corner of whether Starship has the delta-V to launch from Mars surface direct to Earth with 50 tons of cargo...

Payload return shouldn't be a problem in cislunar space...

Case in point: 

Martian 50-t return cargo is doubted again, above,

even though it's well within stated, matter-of-fact capability.

6.9 km/s delta-v for 100 t translates into 7.6 km/s for 50 t, readily exceeding the ~ 6 km/s required from Mars.

[Mackilroy]

Let's not forget uranium and plutonium. Once we can extract/produce these in space for space (so still a way out), the biggest issue with nuclear power in space is gone. That'll make industries which require a lot of power more compact than big powersats.

My understanding is that uranium beyond Earth (at least among the asteroids) is in concentrations thousands of times smaller than the lowest concentrations we've mined here. If you want nuclear energy in space, funding people building D/D fusion reactors is likely a better bet, as then you can obtain deuterium from water nearly everywhere.

[Nilof]

In the inner solar system and in-space, solar is vastly more practical than nuclear in reliability, cost, and power to weight ratio.

On Mars, Uranium concentrations in the ground are higher than on Earth. Though fuel elements are sufficiently low-weight that shipping them from earth is still perfectly viable, especially assuming that a breeder reactor that burns fuel efficiently is used. The mass of the nuclear fuel needed to sustain a colonists indefinitely is literally small compared to the mass of the colonists themselves, let alone the mass of their surrounding infrastructure.

The issue with nuclear reactors is mainly their operational complexity. Fixing a malfunctioning nuclear reactor in a space environment is an absolute PITA.

[high road]

Let's not forget uranium and plutonium. Once we can extract/produce these in space for space (so still a way out), the biggest issue with nuclear power in space is gone. That'll make industries which require a lot of power more compact than big powersats.

My understanding is that uranium beyond Earth (at least among the asteroids) is in concentrations thousands of times smaller than the lowest concentrations we've mined here. If you want nuclear energy in space, funding people building D/D fusion reactors is likely a better bet, as then you can obtain deuterium from water nearly everywhere.

Where do you get that understanding? Is there some geological process that helps concentrate uranium that wouldn't happen in space? Otherwise, we need far more exploration to estimate what we are likely to find.

In the inner solar system and in-space, solar is vastly more practical than nuclear in reliability, cost, and power to weight ratio.

On Mars, Uranium concentrations in the ground are higher than on Earth. Though fuel elements are sufficiently low-weight that shipping them from earth is still perfectly viable, especially assuming that a breeder reactor that burns fuel efficiently is used. The mass of the nuclear fuel needed to sustain a colonists indefinitely is literally small compared to the mass of the colonists themselves, let alone the mass of their surrounding infrastructure.

The issue with nuclear reactors is mainly their operational complexity. Fixing a malfunctioning nuclear reactor in a space environment is an absolute PITA.

Extracting and refing uranium would be much more complex in space. But the main reason not to use it today is because the risk of something going wrong with the launch. So you're not competing with uranium from Earth. Regardless of how compact and easy to ship they are.

As for easy management: the occasional malfunction notwithstanding, maintaining the output of a solar farm that's growing along with the settlement and fuel production, during seasonal dust storms etc, is not a walk in the park either. Or maintaing solar farms on several sides of the moon (eventually, we'll want to move away from the poles) or batteries big enough to outĺast the lunar night. There may be use cases where nuclear submarine sized reactors would be less complex, I think.

edit: fixed quotes. Quoting multiple posts while on my cellphone is quite tricky.

[ppnl]

Where do you get that understanding? Is there some geological process that helps concentrate uranium that wouldn't happen in space? Otherwise, we need far more exploration to estimate what we are likely to find.

On earth uranium is concentrated by hydrothermal and volcanic processes. These are unlikely to happen on asteroids for example. You probably need a planet sized object with an active geology.  And water.

Some ore is as much as 24% uranium but most is far less than 1%. That is orders of magnitude more than the 2.7 parts per million undifferentiated concentration.

[Mackilroy]

Let's not forget uranium and plutonium. Once we can extract/produce these in space for space (so still a way out), the biggest issue with nuclear power in space is gone. That'll make industries which require a lot of power more compact than big powersats.

My understanding is that uranium beyond Earth (at least among the asteroids) is in concentrations thousands of times smaller than the lowest concentrations we've mined here. If you want nuclear energy in space, funding people building D/D fusion reactors is likely a better bet, as then you can obtain deuterium from water nearly everywhere.

Where do you get that understanding? Is there some geological process that helps concentrate uranium that wouldn't happen in space? Otherwise, we need far more exploration to estimate what we are likely to find.

I'm referencing this paper: https://www.sciencedirect.com/science/article/abs/pii/0039914068800311

As for seasonal dust storms, I read somewhere that they have little affect the performance of solar panels on Mars. I'll have to see if I can find the source for that.