3 ms·
Also, almost any Mars mission would involve a lot of heavy lifting into low earth orbit to construct a vehicle that would transport people there and bac
by avar 14y ago
Also, almost any Mars mission would involve a lot of heavy lifting
into low earth orbit to construct a vehicle that would transport
people there and back.
I keep seeing this assertion but I'm genuinely curious to know why this is the case.
If you're going to assemble the vehicle in LEO anyway before you send it off to Mars why is it so much better to do so by lifting up X pieces for assembly with X huge rockets instead of lifting up X * N pieces on X * N smaller rockets?
Sure you get into engineering problems eventually if your rockets are too small, since any single component can't be larger than those rockets can carry. But if nobody even has a design for such an in-orbit-assembled vehicle, then just starting out by making a really big rocket seems to be a case of putting the cart before the horse.
- robbiep 14y agoMy guess, and I'm sure someone more knowledgable will chime in, would be efficiencibutton a larger rocket/lift capability- Defintely with the current 'throwaway' model, where whole rocket costs are ~95%+ cf. fuel; but I believe even with re-usable rockets (as they are aiming for) you have significant cost advantage per kg (or pound if you prefer) from a larger rocket. So, as I see it, less cost, less launches, less messy construction (larger modules/however the beast turns out)
- JoeAltmaier 14y agoMaybe. Or maybe it just means a larger payload. The cost per kg could end up anywhere with new technology. At least in the beginning it might be much higher.
- jbri 14y agoIn the long run, you'd expect carrying heavier payloads to be cheaper per-kg (because you're lifting more payload and less rocket, relatively speaking), but carrying larger payloads to be more expensive (because you need to be using a bigger rocket). Those play against each other to some extent. In the very short term a new technology is likely to be pricier than the existing tried, tested and refined version (especially when you include R&D costs), how long it stays that way is hard to predict.
- stcredzero 14y agoActually, someone came up with a variant of Zubrin's Mars Direct plan that involves in-orbit assembly of pieces launched by existing rockets.