Living on Mars?

[Bucky]

Unless you can show me how that'd even be done, I don't think that is a thing that could happen with the tether-crawler design.

Sure. The crawler gets partway up the tether and then meets and attaches to a separate cable lowered from the station at the geostationary point. The station hooks the other end to the deadweight crawler, which is suspended off to one side of the main tether.

As the ascending crawler climbs, it lowers the deadweight crawler, which provides most of the energy. Motors onboard the station handle the rest. Sometime between when the ascending crawler reaches the geostationary point and when it arrives at the counterweight, the deadweight crawler detaches and falls, taking precautions to avoid striking the tether on the way down.

The main benefit is that reduced energy requirements near the top of the elevator translate to reduced crawler weight at the bottom.

[Rakaydos]

Methane-oxygen rockets are almost certainly not good enough for fuel purposes, and CO2 is far from the only pollutant of concern.

You're welcome to explain that to Elon Musk. He's going all-in on his new methane-burning Raptor engine.

https://www.youtube.com/watch?v=If29t-bEYWM

[Rockphed]

You're welcome to explain that to Elon Musk. He's going all-in on his new methane-burning Raptor engine.

https://www.youtube.com/watch?v=If29t-bEYWM

As with many things, Musk's pursuit of something has very little to do with how effective that thing ends up being.

[LordEntrails]

...
But there's no fundamental reason a rocket cannot me made with enough margin that it refuels and reflies after a single day. (Elon apparently wanted a 12 hour turnaround- the engineers convinced him that 24 hours was reasonably possible.) For the cost of creating a single edge-of-theoretically-possible elevator filament, how many reusable heavy lift rockets can you assemble and get a thousand flights out of, each?...

To be fair, you should say '..how many theoretically reusable heavy lift rockets..'

Because 1000 flight launch vehicles have never been built and are still only theoretical.

[Knaight]

You're welcome to explain that to Elon Musk. He's going all-in on his new methane-burning Raptor engine.

https://www.youtube.com/watch?v=If29t-bEYWM

If this design actually works, I'll eat those words. As is though, I'm roughly as convinced by it as I am by the hyperloop, which appears to be going nowhere fast.

[Lvl 2 Expert]

You're welcome to explain that to Elon Musk. He's going all-in on his new methane-burning Raptor engine.

https://www.youtube.com/watch?v=If29t-bEYWM

He's dropping the car company and the several dozen other projects is funding/advertising?

[monomer]

If this design actually works, I'll eat those words. As is though, I'm roughly as convinced by it as I am by the hyperloop, which appears to be going nowhere fast.

Blue Origin BE-4 is also a Methalox engine. This is the engine that will be used in New Glenn, and probably ULA's Vulcan. I would like to know why you don't think it can be done, though.

(Just as a note, the USAF requires assured access to space, which means they need two distinct launch systems in case one gets grounded. Right now they have Falcon, Atlas, and Delta. Delta is being retired, and they can't use Russian-made RD-180 engines on the Atlas for national security launches. This means they will be dependent on either Vulcan or New Glenn flying. I would be surprised if they were hinging everything on an engine that can't work.)

[Rakaydos]

If this design actually works, I'll eat those words. As is though, I'm roughly as convinced by it as I am by the hyperloop, which appears to be going nowhere fast.

The rocket engine works.

https://www.youtube.com/watch?v=e7kqFt3nID4

The rocket as a whole needs some development and construction, but that's how the world works... the SLS has been in developmenet much longer tha the BFR is expected to, due to the difference between corporate priorities (profit) and govermental priorities. (jobs)

[Bohandas]

As with many things, Musk's pursuit of something has very little to do with how effective that thing ends up being.

Yeah, I have difficulty taking Musk entirely seriously.

Didn't he also once say that he was legitimately worried about the world being overrun by evil robots like in The Matrix or Terminator?

[Rakaydos]

Yeah, I have difficulty taking Musk entirely seriously.

Didn't he also once say that he was legitimately worried about the world being overrun by evil robots like in The Matrix or Terminator?

You clearly havn't been paying attention to modern politics. 'Bots are already being used as a weapon to shape the way people think at a national level. Just because they arnt carrying a gun, doesnt mean they cant be used to change our way of life- just look at the Net Neutrality controversy.

[Bohandas]

Military drones are more Phantom Menace style evil robots, what Musk is worried about is that the robots will take over and turn us into batteries.

[Rakaydos]

Military drones are more Phantom Menace style evil robots, what Musk is worried about is that the robots will take over and turn us into batteries.

Can you source your claim for what musk is worried about? Because twitterbots and facebook fake news pushers are far more dangerous than military drones.

[Lacuna Caster]

Venus is decent, and certain altitudes have survivable air pressures and temperatures. Unfortunately, the denser atmosphere and scarcity of water might make it harder to leave. On the bright side, exosphere skimming during a gravity slingshot could allow Venus to provide Martians with nitrogen for megahabitat atmospheres, and Martians could probably trade a few things for it.

I can buy that Mars is a potential fixer-upper, but colonising Venus seems like a very very long-term project to me. I suppose that if you erected a giant parasol at the lagrange point to cut off sunlight you could cool the surface enough to allow landings, but otherwise you're committed to living in giant blimps above a seething cauldron of volcanic gasses and acid rain, with no particularly easy access to building materials. What's the advantage over living in space?

I vaguely recall that Lunar soil is missing some key elements compared with Mars, so it's not as favourable for long-term settlement projects unless you're willing to trade in large volumes with the asteroid belt. I wouldn't complain if someone wants to fund a settlement, though.

I'm not sure if vertical farming is mature enough to feed a Mars colony, but cultured meat would definitely cut the volume needed to sustain a stable population that doesn't use in vitro fertilization or gametogenesis to resist genetic homogenization.

Explain?

[Lacuna Caster]

The 2017 BFR is fueled with about 4000 tons of Natural Gas (Methane) and Medical grade oxygen. Best estimate put the fuel costs at $500,000 dollars for 150 tons to orbit. (Methane is cheaper per ton than the Falcon 9's Kerosene) The rocket itself is more expensive, but is intended to be flown 1000 times per airframe, amortising the costs significantly.

I personally think that launch loops or space fountains are more plausible than elevators from an engineering perspective, and some analyses put the amortised cost of those approaches as low as 3 dollars per kilo. Still, if Musk is talking about 500K dollars for 150K kilograms of payload, then... that's pretty damn competitive, actually. Huh.

As with many things, Musk's pursuit of something has very little to do with how effective that thing ends up being.

Explain?

[Grey_Wolf_c]

I can buy that Mars is a potential fixer-upper, but colonising Venus seems like a very very long-term project to me. I suppose that if you erected a giant parasol at the lagrange point to cut off sunlight you could cool the surface enough to allow landings, but otherwise you're committed to living in giant blimps above a seething cauldron of volcanic gasses and acid rain, with no particularly easy access to building materials. What's the advantage over living in space?

Does Venus have a half-decent magnetosphere? Protection from solar radiation would be a definite plus.

I would hope that by the time we set up a colony in Venus we'd have mastered robotics to the point they could go down to do the mining for us, rather than send human beings into the mines.

I vaguely recall that Lunar soil is missing some key elements compared with Mars, so it's not as favourable for long-term settlement projects unless you're willing to trade in large volumes with the asteroid belt. I wouldn't complain if someone wants to fund a settlement, though.

Luna's main selling point is the lack of gravity well, and how that makes ship manufacturing, re-servicing and retooling easier (0-g manufacturing might not be that easy). If that is true, then anything missing from Luna will be easy enough to import, precisely because launching ships from Luna will be cheap.

I'm not sure if vertical farming is mature enough to feed a Mars colony, but cultured meat would definitely cut the volume needed to sustain a stable population that doesn't use in vitro fertilization or gametogenesis to resist genetic homogenization.

Explain?

The trivial answer to this would be "because vertical farms are barely mature enough to feed an Earth population". But I suspect you mean the part about IV and genetic homogenization, in which case, I too would like to hear a detailed explanation for that.

GW

[Rakaydos]

I personally think that launch loops or space fountains are more plausible than elevators from an engineering perspective, and some analyses put the amortised cost of those approaches as low as 3 dollars per kilo. Still, if Musk is talking about 500K dollars for 150K kilograms of payload, then... that's pretty damn competitive, actually. Huh.

That's just the fuel costs, but yea. Even allowing for, say, tripling the cost per flight for airframe amortization and maintinance, it's the same order of magnatude as the various launch infrastructure.

Also, check out the Orbital Ring concept- it's basically a space fountain that doesnt touch down anywhere, with relatively short (100-200km) cables to earth keeping it stable.

[Excession]

Does Venus have a half-decent magnetosphere? Protection from solar radiation would be a definite plus.

Venus does not have an internally generated magnetic field, but it's not quite that simple. https://www.astrobio.net/also-in-new...se-from-venus/ has more information. Still sounds like Venus's upper atmosphere is not a great place to be in terms of radiation.

[halfeye]

I can buy that Mars is a potential fixer-upper,

I on the other hand don't think that's so. The gravity is way too low for an Earthlike atmosphere to stay long past it being dropped in.

The lack of gravity is perhaps a problem for child development and human life in general.

It's cold and that can't easily be fixed.

but colonising Venus seems like a very very long-term project to me. I suppose that if you erected a giant parasol at the lagrange point to cut off sunlight you could cool the surface enough to allow landings.

That's what I'm saying, we can make lightsails ten km wide with current tech, and self driving cars look as if they will be here very soon, so that's do-able, and we know that temperate regions drop in temperature 30 degrees centigrade on Earth in half a year, so getting the temperature of Venus down isn't a thousand year problem, though it's not a five week one either.

Once the temperature is somewhere reasonable, plant life would love all the CO2, and bacteria would love the sulphur, then it's a matter of getting some water there, and then it'll be a nice place.

What's the advantage over living in space?

Suitable gravity for Earthlife without messing about with that life. Space is definitely the way to go in the long run, but for a planet other than Earth, Venus looks the best to me.

I vaguely recall that Lunar soil is missing some key elements compared with Mars, so it's not as favourable for long-term settlement projects unless you're willing to trade in large volumes with the asteroid belt. I wouldn't complain if someone wants to fund a settlement, though.

Explain?

The Moon is very near, and the gravity is low enough to get off it again without too much fuss.

It's a couple of weeks away, not a couple of years, so we can get help there, or move someone from there here, if the timescale isn't too tight (appendicitis would have to be dealt with in situ). It's a lot better than Mars in terms of accessibility, and we know the temperature is on average tolerable.

I think a viable Moonbase is one of the first steps we ought to take into space, it's on the way wherever we're going.

[Grey_Wolf_c]

we know the temperature is on average tolerable.

Wait, what?

GW

[Rakaydos]

Wait, what?

GW

Lol... he's not WRONG exactly... but that's the danger of averages. it's too hot during the 14 days of daylight and too cold during the 14 days of night, but if you could average that out somehow, either by being underground or some kind of heat battery, it shouldnt be too bad.

[Grey_Wolf_c]

Lol... he's not WRONG exactly... but that's the danger of averages. it's too hot during the 14 days of daylight and too cold during the 14 days of night, but if you could average that out somehow, either by being underground or some kind of heat battery, it shouldnt be too bad.

Even if I accepted that, wouldn't the likely Lunar base be in the pole, in one of the eternal dark craters where there is a chance to find water?

GW

[Rakaydos]

Even if I accepted that, wouldn't the likely Lunar base be in the pole, in one of the eternal dark craters where there is a chance to find water?

GW

Sure. would be about as "livable" as an antarctic base, if antarctica had no air.

[factotum]

I on the other hand don't think that's so. The gravity is way too low for an Earthlike atmosphere to stay long past it being dropped in.

I'm sure you keep bringing this up, and I keep giving the same answer--define "long". There is evidence that Mars used to have running water on its surface--running water which had time to erode rocks. Therefore, it must have had a decently thick atmosphere for millions of years. I'm pretty sure everybody would be OK with us giving Mars an atmosphere, knowing we'll have to top it up after a few million years.

[Leewei]

@halfeye:

Gravity's impact on child development is potentially a real problem. We need more research on what would happen, but current indications are that microgravity is bad. Mars isn't exactly microgravity (~3/8 G), but could still be problematic. This is your best point against a Martian outpost.

The atmospheric issue is brought on not by gravity, but by solar wind and very weak magnetosphere. Mars' gravity, as low as it is, can sustain an atmosphere with enough pressure to support life. This is supported by the planet's own geological record. We'd still need to somehow produce enough of a magnetic field to deflect the erosive charged particles being kicked out by the sun. Fission plants powering a planet-wide electrical grid would be one possibility. Another one is colliding asteroids in orbit around Mars to produce a substantially larger moon, which would then jump-start convection in the planet's interior by way of tidal forces.

If Mars can sustain an atmosphere, warming is possible using carbon dioxide, methane, or other greenhouse gasses. Between the challenges of heating up or cooling down bodies in a vacuum, heating up is far, far easier to accomplish. (Note that the interior of Mars is toasty. The planet's core is still magma.)

By comparison, Venus has an enormous amount of heat. Even with the sun's radiation blocked, the planet would need ages to cool down. This isn't a thousand year problem, but a million year one. Losing heat into a vacuum is just that slow.

Until we can put structures on Venus that don't immediately melt into slag, we'd be stuck in orbit at microgravity.

I agree with the lunar outpost idea. The moon is certainly the next step in a logical progression from Antarctic stations and ISS. The challenges look similar to those presented by creating an outpost on another planet.

[Tvtyrant]

I imagine the most interesting aspect of colonization is how quickly colonists would become their own species. The gravity on the moon is so low that very large, low muscle humans would quickly become the norm. Less pressure on joints and heart could easily lead to 10+ foot tall humanoids who can't breed with Earthlings at all.

[Grey_Wolf_c]

Another one is colliding asteroids in orbit around Mars to produce a substantially larger moon, which would then jump-start convection in the planet's interior by way of tidal forces.

Oh, there's an interesting idea. It'd take a hellishly large amount of asteroids, though, and I'm not sure how well they'd coalesce into a moon. Wouldn't you need to smack 'em hard enough to melt them together?

Until we can put structures on Venus that don't immediately melt into slag, we'd be stuck in orbit at microgravity.

No, the plan would be to have balloons floating in 1-atm, rather than in orbit. I believe that at that altitude, gravity would still be pretty Earth-like, and the amount of sulfuric acid rain would be manageable. What the people in said balloon cities would do to pass the time, though, that's where "having robots that can go down to the surface to mine" would come in.

ETA:

I imagine the most interesting aspect of colonization is how quickly colonists would become their own species. The gravity on the moon is so low that very large, low muscle humans would quickly become the norm. Less pressure on joints and heart could easily lead to 10+ foot tall humanoids who can't breed with Earthlings at all.

I don't know about that. IVF would allow for a significant period of interbreeding even after the point where it becomes physically unfeasible.

GW

[halfeye]

The atmospheric issue is brought on not by gravity, but by solar wind and very weak magnetosphere. Mars' gravity, as low as it is, can sustain an atmosphere with enough pressure to support life.

Citation needed. The cause of atmosphere loss AIUI is the speed of gas molecules exceeding escape velocity, which is why all that's left is CO2 (which is heavy, and thus has a low enough velocity at current Martian temperatures that it doesn't exceed escape velocity). The kinetic energy of gas molecules depends on temperature, only, that's what temperature is, and thus the speed at a given temperature depends on the mass of the molecule. Hydrogen and helium escape from Earth because their velocity is above escape velocity, luckily hydrogen usually bonds with something else before that happens, but helium is rare and getting rarer.

This is supported by the planet's own geological record.

As guesstimated from Earth. It's possible that at some time a big comet, or a lot of littler ones dumped enough water there to make things flow, but how long that would last is debateable. There can be erosion from sandstorms, and we know there are quite a few of those.

We'd still need to somehow produce enough of a magnetic field to deflect the erosive charged particles being kicked out by the sun. Fission plants powering a planet-wide electrical grid would be one possibility. Another one is colliding asteroids in orbit around Mars to produce a substantially larger moon, which would then jump-start convection in the planet's interior by way of tidal forces.

The gravity is still too low.

If Mars can sustain an atmosphere, warming is possible using carbon dioxide, methane, or other greenhouse gasses. Between the challenges of heating up or cooling down bodies in a vacuum, heating up is far, far easier to accomplish. (Note that the interior of Mars is toasty. The planet's core is still magma.)

That's a very big "if".

By comparison, Venus has an enormous amount of heat. Even with the sun's radiation blocked, the planet would need ages to cool down. This isn't a thousand year problem, but a million year one. Losing heat into a vacuum is just that slow.

As I said, Earth loses 30 degrees celcius in six months, we have less cloud cover, but we aren't half that hot, we need a reasonable simulation of Venus' atmosphere to begin to guess what would happen. If the winds dropped, the back might freeze out too fast.

Until we can put structures on Venus that don't immediately melt into slag, we'd be stuck in orbit at microgravity.

Yeah, we need to get that temperature down, electronics without solder is difficult, iron would hold up, but the electronics would be a problem.

I agree with the lunar outpost idea. The moon is certainly the next step in a logical progression from Antarctic stations and ISS. The challenges look similar to those presented by creating an outpost on another planet.

It's the obvious first place to go after LEO.

[Tvtyrant]

I don't know about that. IVF would allow for a significant period of interbreeding even after the point where it becomes physically unfeasible.

GW

That is fair I suppose. I imagine the communities would seperate pretty quick though, as Mooninites couldn't survive on Earth and Earthlings would be tiny compared to natural Mooninites.

Even 1 generation in would be a big difference, as the cartilidge in a Mooninite would fill with liquid and not compress during the day and would grow more during childhood.

You might get a lot of old folk colonization as it would keep their mobilility more into old age though. The moon as a retirement center is the moat hilarious ending.

[halfeye]

That is fair I suppose. I imagine the communities would seperate pretty quick though, as Mooninites couldn't survive on Earth and Earthlings would be tiny compared to natural Mooninites.

Even 1 generation in would be a big difference, as the cartilidge in a Mooninite would fill with liquid and not compress during the day and would grow more during childhood.

You might get a lot of old folk colonization as it would keep their mobilility more into old age though. The moon as a retirement center is the moat hilarious ending.

I don't think it will happen that quickly, but once people begin to adapt to space, we've achieved it, the colonisation of space is begun, from then on, it's humans in space.

[Grey_Wolf_c]

As I said, Earth loses 30 degrees celcius in six months,

Wait, what? You mean every winter? The heat wasn't lost, it just migrated South.

GW