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#31
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Two Starships in "bolas" rotation
On 19-10-05 23:38 , Alain Fournier wrote:
On Oct/5/2019 at 11:44, Niklas Holsti wrote : On 19-10-03 19:18 , David Spain wrote: There are a TON of issues remaining to get crewed Starships to Mars. Nah, I would say two tons :-) No matter how you slice it, there is complexity to artificial gravity. I have the sneaking suspicion that EM thinks this can be short circuited by routine exercise inside a Starship. If I can compensate for the deleterious effects using exercise, drugs, or alcohol (lol) well... 'tight is right'. :-) I agree that this seems to be the SpaceX plan. And it will probably work, too, at least for the fast and quick transits that SpaceX will probably start with. I think that the SpaceX plan is a bit of a if you build it they will come plan. That is a larger plan than David and I discussed -- we were discussing how SpaceX intends to handle the free-fall physiological problems, and I've seen nothing form Musk or SpaceX that suggests they will have some form of artificial gravity on SS. Your view of the larger SpaceX plan agrees with what Musk has said (some time ago, perhaps he has changed his mind) that SpaceX will focus on the rocket and hope or trust that others will pitch in with life support, Mars suits and habitats, etc. On the other hand, one often stated explanation of SpaceX's success so far is that they have mostly designed and built their own solutions in house, rather than subcontract, at least not subcontract to the "space establishment" companies (and instead engaging water-tower builders, for example). If SS/SH turns out to work, perhaps SpaceX will be inspired and have the resources to solve many of these N tons of other problems. They want to build a rocket that can bring humans to Mars cheaply. They figure that if they send a few people to Mars, even if these few people can't do much on Mars because their spacesuit isn't optimised for Mars and they are unfit to do work because of bone and muscle loss, SpaceX still showed that Mars missions can be done. Others will work on the N tons of details [ choose your value of N, but I agree with you that one is a small value for N :-) ] that will make Mars missions interesting and Mars colonisation possible. Anyway that's my impression. Maybe they are working on all the details and have solutions. But until now they haven't shown so. Shown, no. But from what Musk has said of their plans, SpaceX will not send humans to Mars before there is an operating ISRU propellant plant there, with enough propellant stored for the return trip. ISRU propellant production is one of the larger problems after the rocket. Here some work on the Moon could be good practice, although the in-situ resources on the Moon are different from those on Mars (no carbon dioxide on the Moon, unless the polar ice turns out to be made of fizzy water :-) ). I would have hoped that some people would have started to be vocal about the needs of Mars travellers by now. I mean there should be some company somewhere telling SpaceX, we can make great Mars spacesuits, or we have a great solution for disembarkation and embarkation from a cabin on a rocket on Mars, or artificial gravity or ... Even NASA and other space agencies should be calling SpaceX. Maybe there is some of that going on, but they sure are quiet about it. I suppose many of these people are still skeptical about SS/SH, either of the technical success and/or of Musk's and SpaceX's resources to finish a working SS/SH system (not long ago -- before SS Mk1 started visibly building -- a prominent European space business leader called SS/SH "science fiction"). And of course there is the SLS-mandate-that-must-be-obeyed... -- Niklas Holsti Tidorum Ltd niklas holsti tidorum fi . @ . |
#32
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Two Starships in "bolas" rotation
On 19-10-14 09:47 , JF Mezei wrote:
2 comments/questions: if, after a few months, passengers on ship 1 have consumed more consumables than on ship 2, won't the 2 ships then rotate in really bad way because they wouldn't be at the same mass? If by "consumables" you mean food, it depends on where the "end products" (excrements) go. If they are stored on board, then the ship's mass does not change, and there is no effect on the rotation. If the excrements are ejected, that ship becomes lighter, and the centre of rotation shifts a little towards the other ship. No big deal. Secondly, wouldn't such tethered ships be unable to perform any burns to adjust trajectory/speed during the trip and have to slow their rtation down to 0 before they detach to peform any such burns? Small burns with lateral thrusters could be done during rotation, I think. For larger axial burns with the main engines, stopping the rotation for the burn seems to be simplest. Fancy tricks with forking tethers could perhaps be used to orient the ships properly for axial burns even during rotation. In both cases, the feasibility and efficiency of thrust during rotation depends on the angle between the rotation axis and the desired thrust or delta-V. Lateral thrust along the axis seems simplest, while thrust orthogonal to the axis (in the rotational plane) seems to require pulsing the thrusters at the rotational period. -- Niklas Holsti Tidorum Ltd niklas holsti tidorum fi . @ . |
#33
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Two Starships in "bolas" rotation
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