Especially as we talk about longer term stays on Mars, the Moon or other bodies, more research is needed into the effects of low gravity. Those experiments should absolutely be done in LEO though.
Quote from: intrepidpursuit on 10/31/2017 07:02 pmEspecially as we talk about longer term stays on Mars, the Moon or other bodies, more research is needed into the effects of low gravity. Those experiments should absolutely be done in LEO though.Whether such experiments should be done in LEO or not, I think that there's little chance that they will be! Missions to the Moon and Mars will be the experiments. They'll rely on volunteers and waivers etc. Nobody wants to spend either the money*, or especially the time, needed to conduct such experiments.(* Particularly if it's their own money!)
Two ships docked base to base would have a radius in the nose of ~50 meters, only requiring ~2.6 RPM to get Mars gravity. Cargo would only be limited by the tensioned structural strength of the docking mechanisms.The solar panels would have to be capable of taking the rotation, and would have to be oriented about 90 degrees from the deployment shown (in the same plane as the long axis of the vehicle)For a LEO test, I think this is a feasible configuration.
The downside of tail-to-tail is that it would be harder to move between ships. I think being able to move easily between ships would be an advantage of docking ships together when you're flying multiple passenger ships per mission. It means you can reduce the number of specialists (medical staff, technicians, etc), or having specialists able to work together (instead of being scattered across multiple ships, in order to be available on every ship), or being able to empty one ship while doing major ECLSS repairs, or just for socialising. I could see, in the nose-to-nose configuration, you might have a 4-way docking node (launched and retrieved as cargo by one ship) allowing four BFS's to dock in a pin-wheel formation.
I haven't wanted to start a new thread talking about the same thing but base-to-base, but I haven't heard any good reasons why base-to-base docking isn't a much more secure configuration to perform spin-G.
I mean, the presentation actually *showed* two BFS's docking base to base using secure connections, and low-G acceleration was cited as a way to transfer propellents. You don't need to invent a new attachment point - one already exists
though at Mars G it will be quite possible to jump up or down single floors without hurting yourself.
you could have each crewed BFS docked base-to-base to a cargo BFS to form a spin-able unit. You could then have those two units to form a single assembly if they aligned their dorsal surfaces - and docked using dorsal ports that will be used to access the ground. [...] then 2x sets dorsal ports dock (crew-to-crew BFSs, cargo-to-cargo BFSs), then start to spin at Mars G.
Interesting to think how much before EDL you would separate the ships. 4 ships would probably need to be coming in within half an hour of each other if they are to land anywhere near each other, or alternatively you might detach the cargo ships and let them arrive a day earlier.
Quote from: CuddlyRocket on 11/01/2017 10:27 pmQuote from: intrepidpursuit on 10/31/2017 07:02 pmEspecially as we talk about longer term stays on Mars, the Moon or other bodies, more research is needed into the effects of low gravity. Those experiments should absolutely be done in LEO though.Whether such experiments should be done in LEO or not, I think that there's little chance that they will be! Missions to the Moon and Mars will be the experiments. They'll rely on volunteers and waivers etc. Nobody wants to spend either the money*, or especially the time, needed to conduct such experiments.(* Particularly if it's their own money!)No one will spend their time and money to find out if this is even helpful, but they will spend the time, money, and danger to do it in route, even though it's unclear that it will have any benefits? I am not following your logic.
Quote from: mikelepage on 11/02/2017 04:31 amI haven't wanted to start a new thread talking about the same thing but base-to-base, but I haven't heard any good reasons why base-to-base docking isn't a much more secure configuration to perform spin-G.The main argument is that you have to design around 3 gravity regimes: Earth/Mars down-is-down, zero-g there-is-no-down, and tail-to-tail up-is-down. I don't think it's unviable, but it might make things more awkward to design.
Quote from: mikelepage on 11/02/2017 04:31 amI mean, the presentation actually *showed* two BFS's docking base to base using secure connections, and low-G acceleration was cited as a way to transfer propellents. You don't need to invent a new attachment point - one already existsDuring tail-to-tail refuelling, the attachments are under compression. During tail-to-tail spin, they are under quite significant tension.Again, not impossible to design around, and I suspect the thrust frame will be more than capable of handling the loads, it's just not "it already exists".
Quote from: mikelepage on 11/02/2017 04:31 amI haven't wanted to start a new thread talking about the same thing but base-to-base, but I haven't heard any good reasons why base-to-base docking isn't a much more secure configuration to perform spin-G.The main argument is that you have to design around 3 gravity regimes: Earth/Mars down-is-down, zero-g there-is-no-down, and tail-to-tail up-is-down. I don't think it's unviable, but it might make things more awkward to design. (Testing isn't that hard, though, compared to designing for zero-g. You just flip the test-rig.¹)By contrast, nose-to-nose has the same orientation as on Earth/Mars. So your ECLSS and other plumbing only needs to work on Earth and in orbit.
Has SpaceX ever considered tethering two crew Starships to create artificial gravity enroute to Mars?
Yes
I think Elon stated that the nose would be pointing towards the Sun during flight. I expect for a couple of reasons 1 so solar array could get most energy 2) to limit the effects of solar energy on fuel required for landing. Also if you spin up the ships would mean the solar arrays would then need to withstand partial G forces. Great idea but probably not realistic
Quote from: corneliussulla on 10/16/2017 03:40 pmI think Elon stated that the nose would be pointing towards the Sun during flight. I expect for a couple of reasons 1 so solar array could get most energy 2) to limit the effects of solar energy on fuel required for landing. Also if you spin up the ships would mean the solar arrays would then need to withstand partial G forces. Great idea but probably not realisticThe opposite, keeping the rockets pointed toward the sun at all times, gives you several layers of radiation shielding at no additional mass cost. So is zero g or radiation the bigger danger?
I remember reading a paper several years ago They also mentioned that small differences in gravity between your head and feet could cause issues over time.
Quote from: Dave G on 07/07/2021 10:12 pmI remember reading a paper several years ago They also mentioned that small differences in gravity between your head and feet could cause issues over time.Can you find the paper? This is the opposite to what I've seen. Spin-table experiments seem to suggest that there's no effect from even major g-load differences between head/feet.
Quote from: Paul451 on 07/08/2021 09:17 amQuote from: Dave G on 07/07/2021 10:12 pmI remember reading a paper several years ago They also mentioned that small differences in gravity between your head and feet could cause issues over time.Can you find the paper? This is the opposite to what I've seen. Spin-table experiments seem to suggest that there's no effect from even major g-load differences between head/feet.Spincalc has several listed under 'references'.
I think there are several strong arguments in favour of coupling Starships together and generate a little gravity.My proposal is to have docking adapter in the nose of a Starship an couple several (i.e. 6) Starships to a central hub with docking ports at the circumference.
Quote from: michcies on 08/18/2021 10:10 amI think there are several strong arguments in favour of coupling Starships together and generate a little gravity.My proposal is to have docking adapter in the nose of a Starship an couple several (i.e. 6) Starships to a central hub with docking ports at the circumference.To get SpinCalc to go all-green you need 85m radius for 0.38g, and I'm guessing the max habitable radius in your setup is maybe 20m?Obviously SpinCalc isn't authoritative, and hopefully SpaceX will be able to experiment with this in Earth orbit to actually get some real data on the subject, but until they do I think they'll have to rely on long tethers rather than direct attachment.The nice thing about tethers, of course, is that you can change the radius easily. Start long, reel them in slowly until people start to feel the effects, then back off a bit. If you comfortably get the radius down enough to make direct attachment work then maybe start planning for that approach 26 months later.