12 ms·

1m3 of water weights a metric ton, do the astronauts stay in a broom closet for duration of the flight? You still need (literally) tons of water. And every ton

1m3 of water weights a metric ton, do the astronauts stay in a broom closet for duration of the flight? You still need (literally) tons of water. And every ton you take increases fuel cost. Currently you need what 10-20 trips to fuel for moon. How many trips would you need to fuel trip to mars? You would need a fucking conveyor belt of starship to prep the mission. Who is going to pay for it? And why? Just because the materials for shielding/tools are simple it doesnt make the solution simple.

somenameforme 2y ago
You hit on two really different topics at the same time. So let's hit on the fuel topic first. People tend to draw intuitive parallels of rocket fuel with gas. A short trip doesn't need much, while a long trip needs a lot. But it turns out that's not really how it works in space. In space the way you travel is you point at something, accelerate a bunch, and then coast there. So the typical measurement for something analogous to fuel is called delta-v, or the total required change in velocity. The delta-v required to get to the Moon is around 19km/s. The total delta-v required to get to Mars is around 21km/s. Wiki has a nice table for the delta-v required to get to different locations here. [1] Not only are they very close, but you might also notice that you spend about half your delta-v budget just getting off of Earth's surface! That's why in-orbit refueling is so useful. On the water topic, here's [2] a very readable little writeup on the mass inputs required for longterm space missions. Water makes up the overwhelming majority of your requirements. Starship, in its current form, can carry 150 tons. And that will be substantially increased once the tech is stabilized. A sizable chunk of that storage, for Mars missions, will be water. Also, the big threat is not the persistent ambient radiation, but infrequent extremely high energy bursts from solar weather. [1] - https://en.wikipedia.org/wiki/Delta-v_budget#Delta-vs_between_Earth,_Moon_and_Mars https://en.wikipedia.org/wiki/Delta-v_budget#Delta-vs_betwee... [2] - https://ntrs.nasa.gov/api/citations/20190027563/downloads/20190027563.pdf https://ntrs.nasa.gov/api/citations/20190027563/downloads/20...
- imtringued 2y ago
  Why does this matter? The delta V requirements are so steep Starship can't return from the martian surface. It is a completely different game to go to Mars than to the moon unless you are planning on building a mars gateway in orbit and never landing anywhere.
  - somenameforme 2y ago
    Oh this opens a whole bunch of really interesting topics. One of the most interesting is ISRU - in situ resource utilization. Using what you have available to make further progress. The Sabatier Reaction [1] is one of the single most important factors in our future expansion. Basically, CO2 + Hydrogen => Methane + Water. Mars has essentially infinite CO2 and hydrogen. So this means we can produce essentially infinite methane and water. In fact you can carry out electrolysis on some of the produced hydrogen and feed it back into the system. This leaves you with a final excess product of methane, oxygen, and water. The Starship's engines, uncoincidentally, run on oxygen + methane. So we can locally produce basically limitless amounts of water, oxygen, and rocket fuel on Mars. Of course this begs the question of what we do initially. And like all long distance colonization efforts, you're not sending just a single ship, but rather a small group. Those other ships are carrying additional critical supplies, including fuel. Upon landing those ships can also be used as shelters until something more permanent can be constructed. And the extra fuel provides a means of getting back to Earth if necessary while giving you a big window of time to start establishing basic local infrastructure including energy and methane production. [1] - https://en.wikipedia.org/wiki/Sabatier_reaction https://en.wikipedia.org/wiki/Sabatier_reaction
    - me_me_me 2y ago
      more interestingly, the impact on human psyche is basically unknown. We have meh approximations but just like placebo you cannot fake some things, like 'you are not coming back' condition in an experiment. The permanent dwellings and really whole infrastructure would be underground. Lack of atmo and magnetic field basically forces you to dig down. Limited resources - rudimentary food and water. More less bunker life On top of that 0% prospect of return. Essentially you are doomed to penal colony for the rest of your life. I find it hard to believe anyone would want to sign up to that. And the people who would are absolutely people who should not be sent there. And what happens if earth decides supporting mars outpost is pointless, you want alex jones types create conspiracies that colony is fake and its a tax payer scam? What would that do to minds of those stuck on mars?

somenameforme 2y ago

You hit on two really different topics at the same time. So let's hit on the fuel topic first. People tend to draw intuitive parallels of rocket fuel with gas. A short trip doesn't need much, while a long trip needs a lot. But it turns out that's not really how it works in space. In space the way you travel is you point at something, accelerate a bunch, and then coast there. So the typical measurement for something analogous to fuel is called delta-v, or the total required change in velocity. The delta-v required to get to the Moon is around 19km/s. The total delta-v required to get to Mars is around 21km/s. Wiki has a nice table for the delta-v required to get to different locations here. [1] Not only are they very close, but you might also notice that you spend about half your delta-v budget just getting off of Earth's surface! That's why in-orbit refueling is so useful. On the water topic, here's [2] a very readable little writeup on the mass inputs required for longterm space missions. Water makes up the overwhelming majority of your requirements. Starship, in its current form, can carry 150 tons. And that will be substantially increased once the tech is stabilized. A sizable chunk of that storage, for Mars missions, will be water. Also, the big threat is not the persistent ambient radiation, but infrequent extremely high energy bursts from solar weather. [1] - https://en.wikipedia.org/wiki/Delta-v_budget#Delta-vs_between_Earth,_Moon_and_Mars https://en.wikipedia.org/wiki/Delta-v_budget#Delta-vs_betwee... [2] - https://ntrs.nasa.gov/api/citations/20190027563/downloads/20190027563.pdf https://ntrs.nasa.gov/api/citations/20190027563/downloads/20...

imtringued 2y ago
Why does this matter? The delta V requirements are so steep Starship can't return from the martian surface. It is a completely different game to go to Mars than to the moon unless you are planning on building a mars gateway in orbit and never landing anywhere.
- somenameforme 2y ago
  Oh this opens a whole bunch of really interesting topics. One of the most interesting is ISRU - in situ resource utilization. Using what you have available to make further progress. The Sabatier Reaction [1] is one of the single most important factors in our future expansion. Basically, CO2 + Hydrogen => Methane + Water. Mars has essentially infinite CO2 and hydrogen. So this means we can produce essentially infinite methane and water. In fact you can carry out electrolysis on some of the produced hydrogen and feed it back into the system. This leaves you with a final excess product of methane, oxygen, and water. The Starship's engines, uncoincidentally, run on oxygen + methane. So we can locally produce basically limitless amounts of water, oxygen, and rocket fuel on Mars. Of course this begs the question of what we do initially. And like all long distance colonization efforts, you're not sending just a single ship, but rather a small group. Those other ships are carrying additional critical supplies, including fuel. Upon landing those ships can also be used as shelters until something more permanent can be constructed. And the extra fuel provides a means of getting back to Earth if necessary while giving you a big window of time to start establishing basic local infrastructure including energy and methane production. [1] - https://en.wikipedia.org/wiki/Sabatier_reaction https://en.wikipedia.org/wiki/Sabatier_reaction
  - me_me_me 2y ago
    more interestingly, the impact on human psyche is basically unknown. We have meh approximations but just like placebo you cannot fake some things, like 'you are not coming back' condition in an experiment. The permanent dwellings and really whole infrastructure would be underground. Lack of atmo and magnetic field basically forces you to dig down. Limited resources - rudimentary food and water. More less bunker life On top of that 0% prospect of return. Essentially you are doomed to penal colony for the rest of your life. I find it hard to believe anyone would want to sign up to that. And the people who would are absolutely people who should not be sent there. And what happens if earth decides supporting mars outpost is pointless, you want alex jones types create conspiracies that colony is fake and its a tax payer scam? What would that do to minds of those stuck on mars?