8 ms·

Of course, cost goes up linearly with mass and thus cubed with `r`. Mars missions are expensive enough as it is without making the launch vehicle much bigger th

by WJW 3y ago

Of course, cost goes up linearly with mass and thus cubed with `r`. Mars missions are expensive enough as it is without making the launch vehicle much bigger than required for the mission.

hiddencost 3y ago
Manufacture in space.
- jusssi 3y ago
  Even though Earth orbit is 2/3 the way there, the rocket equation still applies.
  - dylan604 3y ago
    So? Do it in multiple phases just like we've done for the ISS. Isn't that one of the points of SpaceX building cheap/reusable rockets that can be launched quickly? Even Star Trek did this.
pfdietz 3y ago
If going to Mars is worth doing, it's worth doing at scale. Considerations of "it's too expensive" mean one should work to make it cheaper, typically by reducing launch cost. It looks like we'll have launch costs of a < $10/lb to LEO before anyone seriously goes to Mars. Just say no to flags-and-footprints (and SLS); say yes to large scale Mars activities.
- irjustin 3y ago
  > If going to Mars is worth doing, it's worth doing at scale This has too much chicken-egg problem built into it.
  - ben_w 3y ago
    Fortunately, Musk has a specific goal of "dying on Mars, just not on impact", and might be rich enough to make it happen.
- ramon156 3y ago
  If that's how they made decisions NASA would already be broke in the first 3 years
  - pfdietz 3y ago
    NASA isn't leading this parade anymore.
- posix86 3y ago
  I guess that's where politics comes into play. The reason NASA etc. are trying to push costs down isn't necessairily because it wouldn't be worth it if it was more expensive, it's just that projects that are cheaper have a higher chance of getting funded. Also, the value of going to Mars is still highly speculative. Once we reach it with low-cost, smaller missions, it's going to be less speculative, and the risk/reward profile of sending huge spacecrafts will make them more viable.
- myrmidon 3y ago
  > If going to Mars is worth doing, it's worth doing at scale I don't think this is true. If the main value is getting credit for putting the first human there, and doing a few experiments on soil samples or somesuch, then it definitely wouldn't be worth scaling things up, the same way its not worth doing missions to the deep sea, Antarctica or the Moon at scale...
  - hersko 3y ago
    > the main value is getting credit for putting the first human there, and doing a few experiments on soil samples or somesuch... This is old thinking. I take the goal of self sustainable society on Mars very seriously. Will it happen in our lifetime? Probably not, but it is the goal we should be working towards.
    - pc86 3y ago
      Why? I'm not being snarky (at least not intentionally). But you're saying a thing that is at the very least a superpower-level goal, if not a civilization-level goal, that is very clearly not a current priority, should. What's more you're saying it in a way as if it's completely self-evident that we should change our global priorities to focus on this without the slightest evidence supporting that assertion.
      - somenameforme 3y ago
        Well where do you see humanity in the future? In a realistic but also optimistic future? To me all of these futures involves us being a multiplanetary species, and starting to expand out into the cosmos more broadly. It's not only the only way we'll ever become a post-scarcity species, but also the only way we can secure our own survival as a species. There have been countless mass extinction events on Earth, and we're well overdue for another one, and it will come. You're also probably grossly overestimating the cost. The SpaceX Starship program has been privately funded on a budget of ~$2 billion a year including all costs - research and development, construction, launches, etc. And once built it's expected to revolutionize space (again) sending launch costs to less than $10 million per flight, and price per pound to space into the low dollars! And once we can start transiting massive amounts of cargo to Mars, at a very affordable cost, colonization is very much within the domain of possibilities. I would not contrast prices against NASA. NASA is largely used as a tool for pork and graft by Congress, that occasionally launches something. Their latest ship, the SLS [1], is literally reusing Space Shuttle era tech. I mean literally - the SLS is reusing refurbished Space Shuttle RS-25D engines, solid rocket boosters, and more. Managing to spend tens of billions of dollars over 13 years (and counting) to develop this is the special sort of talent you can only get from a company like Boeing. So colonization will be costly, but it's nothing like a civilizational goal. It's just that our civilization only has governments mostly interested in fighting and dominating one another, just as has been the case for the entirety of human civilization. So we never really get to see what we could actually achieve if we tried. But what's finally changed is that these sort of grand achievements no longer require governments. Costs are plummeting at the same time private capital has skyrocketed. So the future looks brighter than ever! [1] - https://en.wikipedia.org/wiki/Space_Launch_System https://en.wikipedia.org/wiki/Space_Launch_System
AYBABTME 3y ago
Which is why minimizing the mass portion budgeted toward shielding makes sense. If you're going to send 10 smaller ships or 1 large one, you better send the 1 large one.
- yetihehe 3y ago
  But one 10x large ship is 10^2 more expensive.
  - ben_w 3y ago
    10x radius is (10^2)x mass, I'm fairly sure they were suggesting 10x mass.
    - Asraelite 3y ago
      You mean 10^3? I don't know where the previous commenter got 10^2 from.
      - ben_w 3y ago
        Shielding is only ever needed on the surface, not the volume, and has a fixed thickness for any given quality, hence ^2 not ^3. https://en.wikipedia.org/wiki/Square–cube_law https://en.wikipedia.org/wiki/Square–cube_law
        Asraelite 3y ago
        Mb, thought it was referring to the cost of the ship overall.
        ben_w 3y ago
        Rereading, I can see why it was unclear. For small crewed ships, shielding will be the dominant part of the overall cost; for large ships it will be a negligible part of the whole cost.
ethbr1 3y ago
Unless you source the mass from something that's already orbiting, like the moon. Since we're mostly talking water, any moon water doesn't have to pay the rocket tax to launch from Earth surface. And for a recurring trip, it'd make way more sense to keep a larger transit ship continually in either orbit or transit, with smaller barebones Earth/Mars cargo/crew transfer craft at either end.
- PaulHoule 3y ago
  It is hard to pencil out lunar materials being cheap, except maybe for use on the moon. If we're at the point where we are capable of in-situ utilization we probably have some kind of Starship-class rocket. The worst part of the "rocket tax" is not that you have to burn a lot of fuel or screw around with stages and refueling, but rather that you (1) throw the rocket away after one use or (2) it is a Great American Boondoggle like the Space Shuttle. I do like the picture though of a lunar mass driver that sends up regolith, metal, or something like that to a catcher at, say, the L1 point.
- Asraelite 3y ago
  A better option would be near-Earth asteroids. These require significantly less fuel to get to than the Moon and many are rich in ice. If you got really really lucky, you could even find one with an orbit similar to the Hohmann transfer path required to get to Mars and visit the asteroid en route. That way you don't even need to expend much fuel to transport the water to Mars; it's almost free. For a return trip you could use Phobos and Deimos for material. They are also extremely easy to land on.

by WJW 3y ago

Of course, cost goes up linearly with mass and thus cubed with `r`. Mars missions are expensive enough as it is without making the launch vehicle much bigger than required for the mission.

hiddencost 3y ago

Manufacture in space.

jusssi 3y ago
Even though Earth orbit is 2/3 the way there, the rocket equation still applies.
- dylan604 3y ago
  So? Do it in multiple phases just like we've done for the ISS. Isn't that one of the points of SpaceX building cheap/reusable rockets that can be launched quickly? Even Star Trek did this.

pfdietz 3y ago

If going to Mars is worth doing, it's worth doing at scale. Considerations of "it's too expensive" mean one should work to make it cheaper, typically by reducing launch cost. It looks like we'll have launch costs of a < $10/lb to LEO before anyone seriously goes to Mars. Just say no to flags-and-footprints (and SLS); say yes to large scale Mars activities.

irjustin 3y ago
> If going to Mars is worth doing, it's worth doing at scale This has too much chicken-egg problem built into it.
- ben_w 3y ago
  Fortunately, Musk has a specific goal of "dying on Mars, just not on impact", and might be rich enough to make it happen.
ramon156 3y ago
If that's how they made decisions NASA would already be broke in the first 3 years
- pfdietz 3y ago
  NASA isn't leading this parade anymore.
posix86 3y ago
I guess that's where politics comes into play. The reason NASA etc. are trying to push costs down isn't necessairily because it wouldn't be worth it if it was more expensive, it's just that projects that are cheaper have a higher chance of getting funded. Also, the value of going to Mars is still highly speculative. Once we reach it with low-cost, smaller missions, it's going to be less speculative, and the risk/reward profile of sending huge spacecrafts will make them more viable.
myrmidon 3y ago
> If going to Mars is worth doing, it's worth doing at scale I don't think this is true. If the main value is getting credit for putting the first human there, and doing a few experiments on soil samples or somesuch, then it definitely wouldn't be worth scaling things up, the same way its not worth doing missions to the deep sea, Antarctica or the Moon at scale...
- hersko 3y ago
  > the main value is getting credit for putting the first human there, and doing a few experiments on soil samples or somesuch... This is old thinking. I take the goal of self sustainable society on Mars very seriously. Will it happen in our lifetime? Probably not, but it is the goal we should be working towards.
  - pc86 3y ago
    Why? I'm not being snarky (at least not intentionally). But you're saying a thing that is at the very least a superpower-level goal, if not a civilization-level goal, that is very clearly not a current priority, should. What's more you're saying it in a way as if it's completely self-evident that we should change our global priorities to focus on this without the slightest evidence supporting that assertion.
    - somenameforme 3y ago
      Well where do you see humanity in the future? In a realistic but also optimistic future? To me all of these futures involves us being a multiplanetary species, and starting to expand out into the cosmos more broadly. It's not only the only way we'll ever become a post-scarcity species, but also the only way we can secure our own survival as a species. There have been countless mass extinction events on Earth, and we're well overdue for another one, and it will come. You're also probably grossly overestimating the cost. The SpaceX Starship program has been privately funded on a budget of ~$2 billion a year including all costs - research and development, construction, launches, etc. And once built it's expected to revolutionize space (again) sending launch costs to less than $10 million per flight, and price per pound to space into the low dollars! And once we can start transiting massive amounts of cargo to Mars, at a very affordable cost, colonization is very much within the domain of possibilities. I would not contrast prices against NASA. NASA is largely used as a tool for pork and graft by Congress, that occasionally launches something. Their latest ship, the SLS [1], is literally reusing Space Shuttle era tech. I mean literally - the SLS is reusing refurbished Space Shuttle RS-25D engines, solid rocket boosters, and more. Managing to spend tens of billions of dollars over 13 years (and counting) to develop this is the special sort of talent you can only get from a company like Boeing. So colonization will be costly, but it's nothing like a civilizational goal. It's just that our civilization only has governments mostly interested in fighting and dominating one another, just as has been the case for the entirety of human civilization. So we never really get to see what we could actually achieve if we tried. But what's finally changed is that these sort of grand achievements no longer require governments. Costs are plummeting at the same time private capital has skyrocketed. So the future looks brighter than ever! [1] - https://en.wikipedia.org/wiki/Space_Launch_System https://en.wikipedia.org/wiki/Space_Launch_System

AYBABTME 3y ago

Which is why minimizing the mass portion budgeted toward shielding makes sense. If you're going to send 10 smaller ships or 1 large one, you better send the 1 large one.

yetihehe 3y ago
But one 10x large ship is 10^2 more expensive.
- ben_w 3y ago
  10x radius is (10^2)x mass, I'm fairly sure they were suggesting 10x mass.
  - Asraelite 3y ago
    You mean 10^3? I don't know where the previous commenter got 10^2 from.
    - ben_w 3y ago
      Shielding is only ever needed on the surface, not the volume, and has a fixed thickness for any given quality, hence ^2 not ^3. https://en.wikipedia.org/wiki/Square–cube_law https://en.wikipedia.org/wiki/Square–cube_law
      - Asraelite 3y ago
        Mb, thought it was referring to the cost of the ship overall.
        ben_w 3y ago
        Rereading, I can see why it was unclear. For small crewed ships, shielding will be the dominant part of the overall cost; for large ships it will be a negligible part of the whole cost.

ethbr1 3y ago

Unless you source the mass from something that's already orbiting, like the moon. Since we're mostly talking water, any moon water doesn't have to pay the rocket tax to launch from Earth surface. And for a recurring trip, it'd make way more sense to keep a larger transit ship continually in either orbit or transit, with smaller barebones Earth/Mars cargo/crew transfer craft at either end.

PaulHoule 3y ago
It is hard to pencil out lunar materials being cheap, except maybe for use on the moon. If we're at the point where we are capable of in-situ utilization we probably have some kind of Starship-class rocket. The worst part of the "rocket tax" is not that you have to burn a lot of fuel or screw around with stages and refueling, but rather that you (1) throw the rocket away after one use or (2) it is a Great American Boondoggle like the Space Shuttle. I do like the picture though of a lunar mass driver that sends up regolith, metal, or something like that to a catcher at, say, the L1 point.
Asraelite 3y ago
A better option would be near-Earth asteroids. These require significantly less fuel to get to than the Moon and many are rich in ice. If you got really really lucky, you could even find one with an orbit similar to the Hohmann transfer path required to get to Mars and visit the asteroid en route. That way you don't even need to expend much fuel to transport the water to Mars; it's almost free. For a return trip you could use Phobos and Deimos for material. They are also extremely easy to land on.