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Okay, let's talk about that. A (very) small roadheader starts at around 8 metric tonnes, and requires around 20kW of power...just for operating the cutting hea

Okay, let's talk about that. A (very) small roadheader starts at around 8 metric tonnes, and requires around 20kW of power...just for operating the cutting head. And that's a really small one. Again, for comparison, Perseverance: 1025kg, 110W of power > It would either need to be Diesel powered That would be a neat trick on a planet with an atmospheric pressure of 610 pascals, where oxygen registers barely above a trace element. > or we'd need a small solar farm Or maybe a not so small one. Using Tesla solar panels https://www.tesla.com/solarpanels https://www.tesla.com/solarpanels as a reference point, they produce up to 400W and are just shy of 2m². That's on Earth. Solar irradiance on Mars is 59% of Earths, so these panels will probably produce ~240W apiece. So to meet the energy requirements of even a small roadheader, we need 83 of these panels, each of which is ~21.5kg in mass, so a total of 1.784t in solar panels alone. Note, that is without cabling, inverters, electronics, spare panels, support structures, etc. ... or the batteries for that matter. Production numbers are also for peak sunlight conditions on Mars, so best-case daylight during the martian summer, and no dust storms. So depending on how heavy the batteries are, I reckon we are already looking at around 12-14 tons of equipment, just for digging with a single machine. And that doesn't include any prefabricated parts, spare parts, airlocks, other heavy machinery, support beams, other auxilliary materials.... I mean, these roadheaders will require new drill heads every now and then, won't they? What's the payload capacity of our current space ship designs again? Because... > It would take months to dig out a cave large enough for 10 to 20 humans, ...we need food and water and medical supplies and power and space suits, and a lot of other things for all these people. Oh, and habitats, because they will need somewhere to live during all these months bevore the cave is ready.

feoren 3y ago
Good point about running a diesel engine on Mars. > So depending on how heavy the batteries are, I reckon we are already looking at around 12-14 tons of equipment, just for digging with a single machine. So you're saying a single Starship could ferry 7 to 8 full rigs? 14 tons of payload is not a big deal right now, much less with 10 years of project-of-national-importance funding. Let's send 2 (one backup) along with lots of other nice goodies for setting up shop then. > So to meet the energy requirements of even a small roadheader, we need 83 of these panels, each of which is ~21.5kg in mass, so a total of 1.784t in solar panels alone. > ... I mean, these roadheaders will require new drill heads every now and then, won't they? 1.8t in solar panels and some extra for new drill heads is really not that much tonnage for the kind of project we're talking about. And remember, we're re-using all this electrical infrastructure for our habitat. > ...we need food and water and medical supplies and power and space suits, and a lot of other things for all these people. Oh, and habitats, because they will need somewhere to live during all these months bevore the cave is ready. They live on Earth before the cave is ready. Why send them at the same time? Remember: the original point was that digging a habitat-sized cave on Mars is really not the hard part here, and something we could accomplish within 10 years if we wanted to. 15 to 20 tons of payload and some moderate engineering challenges have not really disproved that notion. Yes, there are plenty of other hard parts.
- usrbinbash 3y ago
  > So you're saying a single Starship could ferry 7 to 8 full rigs? https://en.wikipedia.org/wiki/SpaceX_Starship_flight_tests https://en.wikipedia.org/wiki/SpaceX_Starship_flight_tests > 14 tons of payload is not a big deal right now Correct...to low earth orbit, it isn't. But we aren't talking about LEO deployment here. We are talking about a flight to Mars. And we won't be deploying that paylod in space, we have to land it, with the ship, with zero support structures on the ground. > They live on Earth before the cave is ready. Why send them at the same time? Then please show me the robotic infrastructure that is capable, with no pre-existing support structures, of building a sealed habitat, after self-unloading from a landed spaceship, and self-assembling itself from it's packaged form. All steps have to be done with no human help on site. Show me that this works here on Earth. And then show me that same thing, but this time, any remote control has a 6-minute delay (and that's still generous, because 3 light minutes is the lowest possible distance between the 2 planets), and it has to be done at in an antarctic dry valley. Then we can talk about that working on Mars.
  - feoren 3y ago
    > https://en.wikipedia.org/wiki/SpaceX_Starship_flight_tests https://en.wikipedia.org/wiki/SpaceX_Starship_flight_tests So we have a vessel capable of ferrying 100 tons to Mars that's already had 55 seconds of controlled flight from a launch where it was missing 3 engines, developed by a single non-government company. And this is supposed to make me pessimistic about a concerted effort from the United States government being able to make this thing (or something like it) work in the next ten years? > But we aren't talking about LEO deployment here. We are talking about a flight to Mars. I was using the payload-to-Mars number, about 100 tons. That does require refueling in orbit. That's expensive, but a pretty simple orbital rendezvous, which we've been doing since 1965. > And we won't be deploying that paylod in space, we have to land it Parachutes, aerobraking, skycranes ... these are well-solved problems on Mars. You think we've already hit the limit of mass that's possible to land on Mars? > Then please show me the robotic infrastructure that is capable, with no pre-existing support structures, of building a sealed habitat, after self-unloading from a landed spaceship Let's revisit the original point being made: > Pretty sure we could design and launch a digging robot in 10 years, I dont really buy that as the bottleneck to mars exploration An extra ~14 tons (half of which we need anyway) and a couple of months of digging is pretty clearly not the bottleneck. But to actually address your point: the robots don't need to make it move-in-ready, they just need to set up enough that the arriving humans can do it relatively quickly (days). If humans have to IKEA-assemble things and weld* some stuff, that's fine. (*yes, harder on Mars, but possible). Since the spaceship itself will have to be a livable habitat, obviously the hope would be to re-use most of that. We send pre-emptive missions to set things up (dig holes, set up solar panels, gather basic resources), and another manned mission to finalize the hab. Bonus points if we can just scooch the ship into the cave after it lands as the initial hab. I think we're just deeply divided on what we think ten thousand focused engineers with hundreds of billions of dollars in budget can accomplish in 10 years. Remember, we're talking about a national or international focused initiative here.

feoren 3y ago

Good point about running a diesel engine on Mars. > So depending on how heavy the batteries are, I reckon we are already looking at around 12-14 tons of equipment, just for digging with a single machine. So you're saying a single Starship could ferry 7 to 8 full rigs? 14 tons of payload is not a big deal right now, much less with 10 years of project-of-national-importance funding. Let's send 2 (one backup) along with lots of other nice goodies for setting up shop then. > So to meet the energy requirements of even a small roadheader, we need 83 of these panels, each of which is ~21.5kg in mass, so a total of 1.784t in solar panels alone. > ... I mean, these roadheaders will require new drill heads every now and then, won't they? 1.8t in solar panels and some extra for new drill heads is really not that much tonnage for the kind of project we're talking about. And remember, we're re-using all this electrical infrastructure for our habitat. > ...we need food and water and medical supplies and power and space suits, and a lot of other things for all these people. Oh, and habitats, because they will need somewhere to live during all these months bevore the cave is ready. They live on Earth before the cave is ready. Why send them at the same time? Remember: the original point was that digging a habitat-sized cave on Mars is really not the hard part here, and something we could accomplish within 10 years if we wanted to. 15 to 20 tons of payload and some moderate engineering challenges have not really disproved that notion. Yes, there are plenty of other hard parts.

usrbinbash 3y ago
> So you're saying a single Starship could ferry 7 to 8 full rigs? https://en.wikipedia.org/wiki/SpaceX_Starship_flight_tests https://en.wikipedia.org/wiki/SpaceX_Starship_flight_tests > 14 tons of payload is not a big deal right now Correct...to low earth orbit, it isn't. But we aren't talking about LEO deployment here. We are talking about a flight to Mars. And we won't be deploying that paylod in space, we have to land it, with the ship, with zero support structures on the ground. > They live on Earth before the cave is ready. Why send them at the same time? Then please show me the robotic infrastructure that is capable, with no pre-existing support structures, of building a sealed habitat, after self-unloading from a landed spaceship, and self-assembling itself from it's packaged form. All steps have to be done with no human help on site. Show me that this works here on Earth. And then show me that same thing, but this time, any remote control has a 6-minute delay (and that's still generous, because 3 light minutes is the lowest possible distance between the 2 planets), and it has to be done at in an antarctic dry valley. Then we can talk about that working on Mars.
- feoren 3y ago
  > https://en.wikipedia.org/wiki/SpaceX_Starship_flight_tests https://en.wikipedia.org/wiki/SpaceX_Starship_flight_tests So we have a vessel capable of ferrying 100 tons to Mars that's already had 55 seconds of controlled flight from a launch where it was missing 3 engines, developed by a single non-government company. And this is supposed to make me pessimistic about a concerted effort from the United States government being able to make this thing (or something like it) work in the next ten years? > But we aren't talking about LEO deployment here. We are talking about a flight to Mars. I was using the payload-to-Mars number, about 100 tons. That does require refueling in orbit. That's expensive, but a pretty simple orbital rendezvous, which we've been doing since 1965. > And we won't be deploying that paylod in space, we have to land it Parachutes, aerobraking, skycranes ... these are well-solved problems on Mars. You think we've already hit the limit of mass that's possible to land on Mars? > Then please show me the robotic infrastructure that is capable, with no pre-existing support structures, of building a sealed habitat, after self-unloading from a landed spaceship Let's revisit the original point being made: > Pretty sure we could design and launch a digging robot in 10 years, I dont really buy that as the bottleneck to mars exploration An extra ~14 tons (half of which we need anyway) and a couple of months of digging is pretty clearly not the bottleneck. But to actually address your point: the robots don't need to make it move-in-ready, they just need to set up enough that the arriving humans can do it relatively quickly (days). If humans have to IKEA-assemble things and weld* some stuff, that's fine. (*yes, harder on Mars, but possible). Since the spaceship itself will have to be a livable habitat, obviously the hope would be to re-use most of that. We send pre-emptive missions to set things up (dig holes, set up solar panels, gather basic resources), and another manned mission to finalize the hab. Bonus points if we can just scooch the ship into the cave after it lands as the initial hab. I think we're just deeply divided on what we think ten thousand focused engineers with hundreds of billions of dollars in budget can accomplish in 10 years. Remember, we're talking about a national or international focused initiative here.