4 ms·

Starship feels like the ultimate engineering gamble, so many moving parts (literally) that getting it right might be as hard as building the habitats it’s meant

Starship feels like the ultimate engineering gamble, so many moving parts (literally) that getting it right might be as hard as building the habitats it’s meant to launch. On nitrogen, I keep wondering: if in-space manufacturing matured, couldn’t we generate atmosphere by cracking water for oxygen and synthesizing nitrogen analogues through hydrogen-based pathways? Or is Earth’s air mix so specific that importing nitrogen stays unavoidable?

bryanlarsen 1y ago
> the ultimate engineering gamble It's a no-lose gamble though. If they fail we still end up with SuperHeavy as a massive, cheaper Falcon like architecture. If it succeeds, finally our space dreams can start to be realized.
jitl 1y ago
Where are you going to get the water? What makes water mass cheaper to orbit compared to nitrogen mass?
- TMEHpodcast 1y ago
  Closed-loop systems like on the ISS already reclaim water from humidity, sweat, and urine, and could be scaled up for larger habitats. Air works similarly: CO₂ is scrubbed, oxygen is regenerated from electrolysis, and trace gases are filtered. I realize you still need an initial stock of oxygen and nitrogen, but isn’t this a problem that could be solved eventually with science?
  - jitl 1y ago
    This is like saying “once we solve the problem, the problem will be solved”
    - TMEHpodcast 1y ago
      Now you’re speaking my language! Let’s get started shall we?
      - econ 1y ago
        After we solve it the problem won't exist anymore. No more deals.
- dylan604 1y ago
  Hang out a big butterfly net and capture the dirty snowballs that float past. There have been lots of new releases of frozen water discoveries on various bodies. Typically in craters that pretty much stay in shadow. Water doesn't seem to be that scarce. It's just not as abundant as on Earth
  - jitl 1y ago
    Going to the moon to get water and bring it back to earth orbit is going to be much more expensive than sending water from earth for a long time.
    - PaulHoule 1y ago
      The image of the really big mass driver that looks like a train you get from O’Neill or Heinlein is obsolete. The US Navy built a 2.5km/s railgun you could fit on a ship. A 3.5 km/s coilgun has to look like the Paris gun to be practical and be able to shoot at a high elevation to hit Earth-Moon L1/L2 or near-Earth space. A railroad car worth of material per day in 1kg or so increments seems plausible. A radiation shield for a deep space station or a simulated asteroid to test mining and manufacturing technology might compete with terrestrial materials. O’Neill’s students never came up with believable catcher and I’ve yet to see one I like. I guess you could get to LEO if you could aerobrake but it looks tough because the outer atmosphere is always changing and a wild shot could trash your target, talk about a space junk problem. The moon has at best a large glacier on it and my guess is Lunarians, if they could vote, would not want to export a gram of it but rather incorporate it into a circular economy.
    - numpad0 1y ago
      you just let fleet of Boeing 702 go fetch couples of comets and asteroids into L4/L5, build Manhattan sized pressure cookers around each piles, allow contents to come to boil on solar heat, and boom, pressurized habitats
- schiffern 1y ago
  >What makes water mass cheaper to orbit compared to nitrogen mass? Nitrogen needs a high-pressure bottle which is wasted mass, whereas water you can send to orbit in thin plastic and fabric bags like they do on ISS. Often on ISS they're actually shipping oxygen as water, but still the wasted mass of water being 11% hydrogen plus the wasted mass of the bag is more efficient than a high pressure gas cylinder.
  - PaulHoule 1y ago
    For my baby Bernal sphere it is shipped either as LN2 or NH4. The large airspace needs a lot of it compared to the water inventory. O’Neill’s published designs except for the Stanford torus were much worse. The water inventory of both N2 and H2O on Earth (0.2 cubic km of water per inhabitant) is extravagant. Ceres is roughly 50% water (like the generic outer solar system or interstellar object) and we could use all of it but it adds up to about the mass of our oceans, and that is most of the water inventory the asteroid belt. I’ve looked at various large rotating structures up to the size of the Banks Orbital and concluded you could solve the structural problems if you could make a reliable journal bearing (structural parts don’t need to be spun) that could handle the velocity difference but no matter what you cannot afford tall mountains or deep oceans.
    - schiffern 1y ago
      Agreed, liquid is probably the way to go. Very tempting to swap nitrogen for helium, but AIUI the main downsides are that the speed of sound is higher so air will leak out from a breach faster, and there may be negative effects on flammability due to helium's high thermal conductivity and low specific heat.
      - Terr_ 1y ago
        Helium gas also leaks a lot, even when everything is normal.
  - hotshiitake 1y ago
    Probably a naive question but would it possible for us to skim gasses from LEO for use in space stations?
PaulHoule 1y ago
Starship to LEO is technologically conservative -- it's hard for me to believe that something like that couldn't be made to work. The uncertainty is that there's not a big market right now for launching things that size but the hope is that the low cost creates the market and maybe Starlink bootstraps it. If it succeeds as an LEO cargo hauler it can be successful without getting man rated or perfecting refueling. Refueling to go father is technically risky and the performance often not that exciting. If you aren't able to refuel on the Moon, Starship lands and returns roughly 3.5 tons, not better than the Apollo LEM which a much larger vehicle that is tall and tippy -- landing on inner solar system bodies that it is covered with boulders. Now it might make sense to put a full load of cargo on it, leave it on the Moon and use it as living space, storage tanks or something, but that's not the plan right now. Refueling on the Moon looks tough: water on the moon looks like a good bet, if we're lucky we find frozen carbon sources at the poles or in asteroid residues on the surface [1], but a hydrogen-oxygen rocket looks like a surer thing. As for alternatives to local nitrogen there is: (1) producing it by nuclear processes which looks tough and (2) various other alternative breathing gases such as Argon, Helium, SF6, etc. [1] Not clear though if we want to spend any of those on reaction mass or incorporate them in a circular economy. Actual colonists would see it differently than flatlanders. (See The Moon is a Harsh Mistress and The Martian Way)
- dylan604 1y ago
  > The uncertainty is that there's not a big market right now for launching things that size Is that true? It seems like there have been the want of lifting large payloads that must be shrunk to fit the actual launch capabilities. This usually means sacrificing so the thing that is launched is not what was really wanted originally. I think the market is there and just waiting for the thing to work.
  - PaulHoule 1y ago
    You may be right. The fact is that Falcon 9 was aimed straight at a huge market. So far SpaceX has been brilliantly successful when it has focused on immediate commercial markets. When it comes to things like space telescopes, a cheap 100 tons to LEO would change the paradigm of how things are developed completely. When it comes to deep space missions that are a one way trip it’s not clear Starship does better than something like the SLS which was cost optimized (see big dumb booster) The way Starship is being developed, with failure being very much an option, could get to LEO with cost optimizations. Mars is a different animal —- if takes 10 tries to stick a landing you’re going to wait 25 years. The key problem of deep space colonization or exploitation is the long turnaround time. I did an unpublished study of the problem of turning asteroids into solar sails and concluded that it would be impossible if you disn’t have a physical twin in space near the Earth to teat anything (like fixes to problems) that needs testing. The problem of landing Starship without chopsticks could be tested exhaustively at White Sands, for instance.
deleted 1y ago
[deleted]
boznz 1y ago
Hard challenges are good and setbacks are to be expected if you are pushing every limit. I would love to be on such a fast moving team with such a massive payoff if they succeed.
MarkusQ 1y ago
> synthesizing nitrogen analogues through hydrogen-based pathways What does this even mean? Transmutation?
pbhjpbhj 1y ago
How far forward are we looking - just use a fusion react to synthesis any material from any other by dissociating baryons then running nucleosynthesis. Stars do it, so we know it works!
- lukan 1y ago
  A working fusion reactor would already open up a lot of opportunities.

bryanlarsen 1y ago

> the ultimate engineering gamble It's a no-lose gamble though. If they fail we still end up with SuperHeavy as a massive, cheaper Falcon like architecture. If it succeeds, finally our space dreams can start to be realized.

jitl 1y ago

Where are you going to get the water? What makes water mass cheaper to orbit compared to nitrogen mass?

TMEHpodcast 1y ago
Closed-loop systems like on the ISS already reclaim water from humidity, sweat, and urine, and could be scaled up for larger habitats. Air works similarly: CO₂ is scrubbed, oxygen is regenerated from electrolysis, and trace gases are filtered. I realize you still need an initial stock of oxygen and nitrogen, but isn’t this a problem that could be solved eventually with science?
- jitl 1y ago
  This is like saying “once we solve the problem, the problem will be solved”
  - TMEHpodcast 1y ago
    Now you’re speaking my language! Let’s get started shall we?
    - econ 1y ago
      After we solve it the problem won't exist anymore. No more deals.
dylan604 1y ago
Hang out a big butterfly net and capture the dirty snowballs that float past. There have been lots of new releases of frozen water discoveries on various bodies. Typically in craters that pretty much stay in shadow. Water doesn't seem to be that scarce. It's just not as abundant as on Earth
- jitl 1y ago
  Going to the moon to get water and bring it back to earth orbit is going to be much more expensive than sending water from earth for a long time.
  - PaulHoule 1y ago
    The image of the really big mass driver that looks like a train you get from O’Neill or Heinlein is obsolete. The US Navy built a 2.5km/s railgun you could fit on a ship. A 3.5 km/s coilgun has to look like the Paris gun to be practical and be able to shoot at a high elevation to hit Earth-Moon L1/L2 or near-Earth space. A railroad car worth of material per day in 1kg or so increments seems plausible. A radiation shield for a deep space station or a simulated asteroid to test mining and manufacturing technology might compete with terrestrial materials. O’Neill’s students never came up with believable catcher and I’ve yet to see one I like. I guess you could get to LEO if you could aerobrake but it looks tough because the outer atmosphere is always changing and a wild shot could trash your target, talk about a space junk problem. The moon has at best a large glacier on it and my guess is Lunarians, if they could vote, would not want to export a gram of it but rather incorporate it into a circular economy.
  - numpad0 1y ago
    you just let fleet of Boeing 702 go fetch couples of comets and asteroids into L4/L5, build Manhattan sized pressure cookers around each piles, allow contents to come to boil on solar heat, and boom, pressurized habitats
schiffern 1y ago
>What makes water mass cheaper to orbit compared to nitrogen mass? Nitrogen needs a high-pressure bottle which is wasted mass, whereas water you can send to orbit in thin plastic and fabric bags like they do on ISS. Often on ISS they're actually shipping oxygen as water, but still the wasted mass of water being 11% hydrogen plus the wasted mass of the bag is more efficient than a high pressure gas cylinder.
- PaulHoule 1y ago
  For my baby Bernal sphere it is shipped either as LN2 or NH4. The large airspace needs a lot of it compared to the water inventory. O’Neill’s published designs except for the Stanford torus were much worse. The water inventory of both N2 and H2O on Earth (0.2 cubic km of water per inhabitant) is extravagant. Ceres is roughly 50% water (like the generic outer solar system or interstellar object) and we could use all of it but it adds up to about the mass of our oceans, and that is most of the water inventory the asteroid belt. I’ve looked at various large rotating structures up to the size of the Banks Orbital and concluded you could solve the structural problems if you could make a reliable journal bearing (structural parts don’t need to be spun) that could handle the velocity difference but no matter what you cannot afford tall mountains or deep oceans.
  - schiffern 1y ago
    Agreed, liquid is probably the way to go. Very tempting to swap nitrogen for helium, but AIUI the main downsides are that the speed of sound is higher so air will leak out from a breach faster, and there may be negative effects on flammability due to helium's high thermal conductivity and low specific heat.
    - Terr_ 1y ago
      Helium gas also leaks a lot, even when everything is normal.
- hotshiitake 1y ago
  Probably a naive question but would it possible for us to skim gasses from LEO for use in space stations?

PaulHoule 1y ago

Starship to LEO is technologically conservative -- it's hard for me to believe that something like that couldn't be made to work. The uncertainty is that there's not a big market right now for launching things that size but the hope is that the low cost creates the market and maybe Starlink bootstraps it. If it succeeds as an LEO cargo hauler it can be successful without getting man rated or perfecting refueling. Refueling to go father is technically risky and the performance often not that exciting. If you aren't able to refuel on the Moon, Starship lands and returns roughly 3.5 tons, not better than the Apollo LEM which a much larger vehicle that is tall and tippy -- landing on inner solar system bodies that it is covered with boulders. Now it might make sense to put a full load of cargo on it, leave it on the Moon and use it as living space, storage tanks or something, but that's not the plan right now. Refueling on the Moon looks tough: water on the moon looks like a good bet, if we're lucky we find frozen carbon sources at the poles or in asteroid residues on the surface [1], but a hydrogen-oxygen rocket looks like a surer thing. As for alternatives to local nitrogen there is: (1) producing it by nuclear processes which looks tough and (2) various other alternative breathing gases such as Argon, Helium, SF6, etc. [1] Not clear though if we want to spend any of those on reaction mass or incorporate them in a circular economy. Actual colonists would see it differently than flatlanders. (See The Moon is a Harsh Mistress and The Martian Way)

dylan604 1y ago
> The uncertainty is that there's not a big market right now for launching things that size Is that true? It seems like there have been the want of lifting large payloads that must be shrunk to fit the actual launch capabilities. This usually means sacrificing so the thing that is launched is not what was really wanted originally. I think the market is there and just waiting for the thing to work.
- PaulHoule 1y ago
  You may be right. The fact is that Falcon 9 was aimed straight at a huge market. So far SpaceX has been brilliantly successful when it has focused on immediate commercial markets. When it comes to things like space telescopes, a cheap 100 tons to LEO would change the paradigm of how things are developed completely. When it comes to deep space missions that are a one way trip it’s not clear Starship does better than something like the SLS which was cost optimized (see big dumb booster) The way Starship is being developed, with failure being very much an option, could get to LEO with cost optimizations. Mars is a different animal —- if takes 10 tries to stick a landing you’re going to wait 25 years. The key problem of deep space colonization or exploitation is the long turnaround time. I did an unpublished study of the problem of turning asteroids into solar sails and concluded that it would be impossible if you disn’t have a physical twin in space near the Earth to teat anything (like fixes to problems) that needs testing. The problem of landing Starship without chopsticks could be tested exhaustively at White Sands, for instance.

deleted 1y ago

[deleted]

boznz 1y ago

Hard challenges are good and setbacks are to be expected if you are pushing every limit. I would love to be on such a fast moving team with such a massive payoff if they succeed.

MarkusQ 1y ago

> synthesizing nitrogen analogues through hydrogen-based pathways What does this even mean? Transmutation?

pbhjpbhj 1y ago

How far forward are we looking - just use a fusion react to synthesis any material from any other by dissociating baryons then running nucleosynthesis. Stars do it, so we know it works!

lukan 1y ago
A working fusion reactor would already open up a lot of opportunities.