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> You keep raising these logistical issues like you’re the only person who ever thought of them. Better than to hand-wave them wouldn't you agree? Because thes

> You keep raising these logistical issues like you’re the only person who ever thought of them. Better than to hand-wave them wouldn't you agree? Because these issues are real, hard and very limiting factors, and they don't go away by throwing money at them. And I'm pretty sure I am not the only person who keeps raising these issues. > Serious plans involve sending hundreds of rockets every year That would be a really neat trick. Mars's synodic period with Earth is 780 days (about 26 months) and the resulting transfer window lasts a few weeks at most. So if you want to send even 100 rockets per year, you have to start +200 rockets within that launch window. To put that into perspective, since 1960 there were a grand total of 50 Mars missions, that includes unsuccessful ones, which were more than half: https://en.wikipedia.org/wiki/List_of_missions_to_Mars https://en.wikipedia.org/wiki/List_of_missions_to_Mars Most of these missions didn't land anything on Mars, and not a single one involved landing the spaceship itself, or had even remotely the kind of payload capacity that a colonisation effort requires. So unless someone has a workable idea for a completely new propulsion system, I'm afraid there won't be "hundreds of rockets every year". Edit: Oh, I almost forgot, small question: How do these "hundreds of rockets per year" get back to Earth? Because, if they don't, well, that's gonna up the launch costs somewhat, wouldn't it?

mr_toad 3y ago
It’s more complicated than that. Cargo rockets don’t all need to be launched at once, they just need to be ready to burn in the launch window. In fact because they’ll need to be refuelled in orbit they have to be launched before the launch window anyway. The passenger rockets will be the last to launch. Optimal transfer orbits have short windows, but there are other orbits available if you’re prepared to wait longer, including ballistic capture orbits, elliptic transfer orbits, and making use of aero braking (skimming through the high atmosphere) for orbital capture. As for the return journey, it’s unlikely that many of the initial rockets will be coming back. Return journeys will likely be limited to passenger rockets. There won’t be much else to bring back until there is sufficient infrastructure on Mars.
- usrbinbash 3y ago
  > Cargo rockets don’t all need to be launched at once, they just need to be ready to burn in the launch window. So what's the plan, launch all those rockets into LEO, and then have them sit there for up to 2 years before sending them on their merry way? Whos doing maintenance? Who repairs these rockets when they get hit by space debris? Who'd even know one was damaged? What's the backup plan when almost inevitably some of them will fail come travel-day? More rockets? Whos doing maintenance on them, and who pays for them? Where are all these rockets coming from btw.? Spaceships aint cheap, they have to earn their keep by doing things like ferrying commercial cargo into LEO. Who can afford to have a fleet of them sitting around doing nothing? Look, I'm not saying that any of this is impossible. I'm just saying that a VERY hard task, that we have never done before, just got an order of magnitude harder. At what point in this hardship am I allowed to wave a little cost-benefit-analysis and ask what exactly we gain from sending people to Mars (aka. nothing that can't be done better with robotic probes)? > Return journeys will likely be limited to passenger rockets. Let's start with: return journeys will be limited to rockets that are still operational after landing in a rock-desert, with zero support structures, on a sheet of powdery regolith-dust, and after having been blasted for months with Martian dust-storms, and subjected to extreme temperature differentials.
actionfromafar 3y ago
You could launch 200 rockets the same day if you wanted to. These things are exactly what throwing money at works for. If you have a really deep pipeline of several, the rockets could also be coming home - but cheap transfers take a really long time.
- usrbinbash 3y ago
  > You could launch 200 rockets the same day if you wanted to. No, I can launch 200 rockets the same day if I have sufficient rockets, launch pads, reload-capacity on these pads, fuel, and personnel. We have none of these things, and they cannot be solved by throwing money either. Just one example why not: Launch sites have geographic requirements. > If you have a really deep pipeline of several, the rockets could also be coming home A pipeline of what, rockets!? The fuel-requirements of a spaceship far outstrip it's payload capacity. That's not me saying that, but physics. So I have to launch M rockets to bring N rockets back home, with M being a multiple of N. And then to bring M home, I have to launch L rockets, with L being a multiple of M. Did anyone say "geometric growth"?
  - notfish 3y ago
    Mars has water and CO2, thats why starship uses methane. You can make fuel on mars.
    - usrbinbash 3y ago
      > thats why starship uses methane No, that's not why. Starship uses Methane/LOX because almost all modern rocket engines do: https://en.wikipedia.org/wiki/Category:Rocket_engines_using_methane_propellant https://en.wikipedia.org/wiki/Category:Rocket_engines_using_... > Mars has water and CO2 Yes, it does. What is doesn't have: lots of available energy, industrial facilities, storage tanks, or any of the other things required to actually make in-situ methane/LOX production feasible. You don't have to believe me, the helpful folks at CSS have provided all the numbers and background data: https://www.youtube.com/watch?v=Wum8_8sWdeU https://www.youtube.com/watch?v=Wum8_8sWdeU https://www.youtube.com/watch?v=GHjOXvmuZWQ https://www.youtube.com/watch?v=GHjOXvmuZWQ https://www.youtube.com/watch?v=s-MQrp2P2GI https://www.youtube.com/watch?v=s-MQrp2P2GI

mr_toad 3y ago

It’s more complicated than that. Cargo rockets don’t all need to be launched at once, they just need to be ready to burn in the launch window. In fact because they’ll need to be refuelled in orbit they have to be launched before the launch window anyway. The passenger rockets will be the last to launch. Optimal transfer orbits have short windows, but there are other orbits available if you’re prepared to wait longer, including ballistic capture orbits, elliptic transfer orbits, and making use of aero braking (skimming through the high atmosphere) for orbital capture. As for the return journey, it’s unlikely that many of the initial rockets will be coming back. Return journeys will likely be limited to passenger rockets. There won’t be much else to bring back until there is sufficient infrastructure on Mars.

usrbinbash 3y ago
> Cargo rockets don’t all need to be launched at once, they just need to be ready to burn in the launch window. So what's the plan, launch all those rockets into LEO, and then have them sit there for up to 2 years before sending them on their merry way? Whos doing maintenance? Who repairs these rockets when they get hit by space debris? Who'd even know one was damaged? What's the backup plan when almost inevitably some of them will fail come travel-day? More rockets? Whos doing maintenance on them, and who pays for them? Where are all these rockets coming from btw.? Spaceships aint cheap, they have to earn their keep by doing things like ferrying commercial cargo into LEO. Who can afford to have a fleet of them sitting around doing nothing? Look, I'm not saying that any of this is impossible. I'm just saying that a VERY hard task, that we have never done before, just got an order of magnitude harder. At what point in this hardship am I allowed to wave a little cost-benefit-analysis and ask what exactly we gain from sending people to Mars (aka. nothing that can't be done better with robotic probes)? > Return journeys will likely be limited to passenger rockets. Let's start with: return journeys will be limited to rockets that are still operational after landing in a rock-desert, with zero support structures, on a sheet of powdery regolith-dust, and after having been blasted for months with Martian dust-storms, and subjected to extreme temperature differentials.

actionfromafar 3y ago

You could launch 200 rockets the same day if you wanted to. These things are exactly what throwing money at works for. If you have a really deep pipeline of several, the rockets could also be coming home - but cheap transfers take a really long time.

usrbinbash 3y ago
> You could launch 200 rockets the same day if you wanted to. No, I can launch 200 rockets the same day if I have sufficient rockets, launch pads, reload-capacity on these pads, fuel, and personnel. We have none of these things, and they cannot be solved by throwing money either. Just one example why not: Launch sites have geographic requirements. > If you have a really deep pipeline of several, the rockets could also be coming home A pipeline of what, rockets!? The fuel-requirements of a spaceship far outstrip it's payload capacity. That's not me saying that, but physics. So I have to launch M rockets to bring N rockets back home, with M being a multiple of N. And then to bring M home, I have to launch L rockets, with L being a multiple of M. Did anyone say "geometric growth"?
- notfish 3y ago
  Mars has water and CO2, thats why starship uses methane. You can make fuel on mars.
  - usrbinbash 3y ago
    > thats why starship uses methane No, that's not why. Starship uses Methane/LOX because almost all modern rocket engines do: https://en.wikipedia.org/wiki/Category:Rocket_engines_using_methane_propellant https://en.wikipedia.org/wiki/Category:Rocket_engines_using_... > Mars has water and CO2 Yes, it does. What is doesn't have: lots of available energy, industrial facilities, storage tanks, or any of the other things required to actually make in-situ methane/LOX production feasible. You don't have to believe me, the helpful folks at CSS have provided all the numbers and background data: https://www.youtube.com/watch?v=Wum8_8sWdeU https://www.youtube.com/watch?v=Wum8_8sWdeU https://www.youtube.com/watch?v=GHjOXvmuZWQ https://www.youtube.com/watch?v=GHjOXvmuZWQ https://www.youtube.com/watch?v=s-MQrp2P2GI https://www.youtube.com/watch?v=s-MQrp2P2GI