Had a fairly over the top thought, certainly not for initial missionsElon Musk talks about getting to a point of sending many ships in a single launch window. What if these all docked with a lightweight central hub for the flight? The central hub would probably be some sort of cycler. This cylindrical arrangement of ships with engines on the outer side would also provide a fair bit of shielding, should that prove to be an issue.
Obvious advantages: less medical problems from zero gravity, easier life on board like eating, toilet, washing, etc. Less problems to find zero g solutions for trivial everyday stuff like washing clothes, pumping liquids, probably easier design of the life support system.Obvious disadvantages: more difficult solar power generation, communication with Earth and Mars, additional mass for the nose connection system, difficult or near impossible to do course corrections, spin up and spin down difficult to Orchestra without introducing oscillations. Oscillations due to mass (people) moving around in both ships. Indifferent: I don't think radiation shielding is a thing in general, can't get much worse than it is already. Maybe a total mass gain, despite extra mass of the cable system. Would require extensive engineering and tradeoff.
Quote from: KelvinZero on 08/06/2017 12:22 amHad a fairly over the top thought, certainly not for initial missionsElon Musk talks about getting to a point of sending many ships in a single launch window. What if these all docked with a lightweight central hub for the flight? The central hub would probably be some sort of cycler. This cylindrical arrangement of ships with engines on the outer side would also provide a fair bit of shielding, should that prove to be an issue.I think that's a very good idea! Would you point the rotational axis of the central hub towards the sun, for easier solar power generation?Would the central hub make steering corrections or the connected ships?
Just saw some issues with the cycler idea. With 3 month earth-mars times it probably needs 4 synods to return home. Maybe it can't be a true cycler in which case how does it brake into mars orbit, or maybe this thing passes mars and visits the asteroid belt, and you have 4 of them. Not as simple as it first sounded.Two ships with cables has a lot less question marks, especially if the ship is already designed to be lifted from the nose under 1g like in the animations.(Off topic, another of my hobby horses is good VR for space travellers. Spin gravity creates a lot of design constraints and you will still be in a cramped spaceship. Good VR, a treadmill and elastic bands could let you jog though expansive fantasy worlds for hours every day.)
How fast would the ships need to spin?, and could this make looking trough a window still pleasant?
Quote from: KelvinZero on 08/06/2017 09:39 amJust saw some issues with the cycler idea. With 3 month earth-mars times it probably needs 4 synods to return home. Maybe it can't be a true cycler in which case how does it brake into mars orbit, or maybe this thing passes mars and visits the asteroid belt, and you have 4 of them. Not as simple as it first sounded.Two ships with cables has a lot less question marks, especially if the ship is already designed to be lifted from the nose under 1g like in the animations.(Off topic, another of my hobby horses is good VR for space travellers. Spin gravity creates a lot of design constraints and you will still be in a cramped spaceship. Good VR, a treadmill and elastic bands could let you jog though expansive fantasy worlds for hours every day.)Assuming a cycler central hub takes to long.I think this central rotating hub structure should brake the same way as it's accelerates, with a few Raptor engines.I know this consumes a lot of fuel, but this amount of fuel/engines could be minimized by pumping from Earth tankers only the required fuel for accelerating.And for braking at mars pumping fuel from the connected Spaceships.The central rotating hub structure can also double as a Mars fluids depot in orbit for mars tankers when they're full at the surface. It makes more sense to store the bulk of the liquids in mars orbit, than on the surface.Spin gravity begins to feel like normal gravity the longer the cable is, so VR would feel similar to VR on earth.Of topic:Does anyone have an idea about how much fuel would be left in a fully loaded Mars tanker when it reaches Mars orbit?
Of topic:Does anyone have an idea about how much fuel would be left in a fully loaded Mars tanker when it reaches Mars orbit?
Quote from: Peter.Colin on 08/06/2017 10:43 amOf topic:Does anyone have an idea about how much fuel would be left in a fully loaded Mars tanker when it reaches Mars orbit?A cargo ITS would lift 300t to LEO and can land 450t on Mars when loaded with extra cargo in LEO and going on a slow trajectory. A tanker should be able to land at least those 450t in propellant on Mars. If that would make sense. Maybe as a rescue mission for the first crew if sabatier fuel ISRU fails. Enough methane but LOX would still need to be produced from atmospheric CO2. An unlikely string of events.
If the ship can reach Mars in under six months, why in the world would you spend so much mass and added complexity to provide artificial gravity? We know that crews can be walking on Earth within a day or two of return from the ISS (with some restrictions), and in an emergency can get themselves out of a Soyuz unaided after a bad landing. The gravity on Mars is one fourth of ours. They don't have to leap out of their couches and start heavy lifting immediately after touchdown. Spending years going to Saturn? Then maybe we need something. But not for Mars.
>Because it would start to smell, washing clothes
washing yourself, going to the toilet is not easy without gravity.
I hope one day there will be a ship with centripetal gravity, but early mars settlement ships don't need that development burden.
Quote from: intrepidpursuit on 08/07/2017 10:42 pmI hope one day there will be a ship with centripetal gravity, but early mars settlement ships don't need that development burden.This is why I suggested maybe moving the goalposts to the saturn mission. (Actually someone else suggested it)
What I mean is, I think it is better to just discuss it as a technical problem. It is after you have sorted out how difficult it is that you have the basis to argue where it could be useful and where it is not worth the bother.
If the ship can reach Mars in under six months, why in the world would you spend so much mass and added complexity to provide artificial gravity?
We know that crews can be walking on Earth within a day or two of return from the ISS