Why? Being actually docked makes them more susceptible to common failures. On explosion on one may damage both of them.They could still occasionally meet up and hang out or exchange personnel.
Quote from: Robotbeat on 09/19/2022 04:54 pmWhy? Being actually docked makes them more susceptible to common failures. On explosion on one may damage both of them.They could still occasionally meet up and hang out or exchange personnel.Ships floating in tandem could bump against each other, but not if they are firmly docked together. As long term co-travelers, I believe this is safer. …
Quote from: Ionmars on 09/19/2022 05:09 pmQuote from: Robotbeat on 09/19/2022 04:54 pmWhy? Being actually docked makes them more susceptible to common failures. On explosion on one may damage both of them.They could still occasionally meet up and hang out or exchange personnel.Ships floating in tandem could bump against each other, but not if they are firmly docked together. As long term co-travelers, I believe this is safer. …They wouldn’t be merely floating but spinning. No chance of accidental recontact if the cable is cut while spinning as they’d be flying in opposite directions compared to their center of mass.
,,,A simple truss, basically attaching where the chopsticks hook under the forward flaps, could connect the two to spin baton (or nunchuck) style, engines outward. It would solve the problems you get with tethers in space snapping around, wobbling etc. Assemble from a kit in the orbital staging area, maybe it has some solar panels for extra transit power. Discard before Mars interface.
No, I mean send a depot by itself to Mars leave it there. Then use it for all return traffic from Mars. That might make sense, e.g. if you were sending very heavy loads back for some reason. (I thought, though, that a fully fueled Starship could go from Mars surface back to Earth orbit without needing extra fuel. Did I imagine that?)But, even so, that's one depot in LEO and one depot in LMO. Maybe two each for redundancy. But I don't see the value in sending a depot there and back with every starship. Not for refueling purposes, anyway.
One way to accommodate gravity reversals is to design a gravity couch that can adjust to both takeoff and artificial gravity during transit. A gravity couch that could be removed from the floor and latched onto the ceiling would meet this requirement. This couch could be incorporated into an arrangement of sleep/EDL cubicles inside one level of a multi-level crew cabin, as suggested by the sketch below.
Quote from: Ionmars on 09/19/2022 02:28 pmOne way to accommodate gravity reversals is to design a gravity couch that can adjust to both takeoff and artificial gravity during transit. A gravity couch that could be removed from the floor and latched onto the ceiling would meet this requirement. This couch could be incorporated into an arrangement of sleep/EDL cubicles inside one level of a multi-level crew cabin, as suggested by the sketch below.This can't work because the center of rotation is not stable. Reference the intermediate axis theorem (aka tennis racket theorem).Connecting the two Starships end-to-end creates a long cylinder. Any imbalance along the cylinder immediately starts a wobble, which quickly devolves into the two tips of the Starships rotating over each other - while the cylinder is still spinning on its original short axis. So you have rotations happening in two different dimensions at the same time, creating centripetal forces that are not what you want. Not good.In the short term Elon Musk is assuming that humans will be able to get to surface of Mars quick enough before any zero-G issues arise. Long term if this turns out not to be the right strategy then I think we'll see some form of Mars cyclers being built that still can leverage the advantages of the Starship.
I was aiming to kill two birds with one stone. First, you need a counterweight to balance a rotating crew ship to Mars. When preparing for a return trip to Earth you will need an accumulator in LMO in the same way you would employ one in LEO. The same accumulator ship can perform both roles.
...... A single Starship spinning end over end (20-25m radius) will be long enough to keep spin rates at 4rpm or below for Mars equivalent G (not ideal of course, but sufficient). The issue (and ongoing argument across many of these threads) has been about having an internal structure that needs to be reconfigurable for zero-G, upside-down and right-way up operations. Having a dedicated cruise phase starship that would be able to just do nose down spin G helps this issue too.
Quote from: mikelepage on 09/20/2022 10:05 am...... A single Starship spinning end over end (20-25m radius) will be long enough to keep spin rates at 4rpm or below for Mars equivalent G (not ideal of course, but sufficient). The issue (and ongoing argument across many of these threads) has been about having an internal structure that needs to be reconfigurable for zero-G, upside-down and right-way up operations. Having a dedicated cruise phase starship that would be able to just do nose down spin G helps this issue too.Mike, I think you are correct. For the first few flights to Mars, early pioneers will have to put up with a higher rate of spin and its coriolis effects to achieve artificial gravity at 0.38g to Mars. Returning to Earth this way may be problematic for their health because they would not be in good shape to tolerate Earth 1.0g.As far as I can tell, this is not a solved problem in either NASA or SpaceX quarters.When we start getting paid passengers for the Mars trip it may be time to consider my approach to achieve a more comfortable and healthful passage.
......Has anyone shown what the effects of any gravity between 0 and 1g would do to the human body long term?Are we building hypothetical ship designs on assumptions.
......This can't work because the center of rotation is not stable. Reference the intermediate axis theorem (aka tennis racket theorem).Connecting the two Starships end-to-end creates a long cylinder. Any imbalance along the cylinder immediately starts a wobble, which quickly devolves into the two tips of the Starships rotating over each other - while the cylinder is still spinning on its original short axis. So you have rotations happening in two different dimensions at the same time, creating centripetal forces that are not what you want. Not good.In the short term Elon Musk is assuming that humans will be able to get to surface of Mars quick enough before any zero-G issues arise. Long term if this turns out not to be the right strategy then I think we'll see some form of Mars cyclers being built that still can leverage the advantages of the Starship.
Quote from: RamsesBic on 09/20/2022 11:35 am......Has anyone shown what the effects of any gravity between 0 and 1g would do to the human body long term?Are we building hypothetical ship designs on assumptions.We have experience with missions at ISS in essentially zero gravity. Returning after 6 months astronauts are still alive, but not much more. We do not have experience at 0.38g, which is better than ISS but would be for longer duration, at least two years between synods. Some of these conditions are not feasible to simulate on Earth.
Quote from: Ionmars on 09/20/2022 11:24 amQuote from: mikelepage on 09/20/2022 10:05 am...... A single Starship spinning end over end (20-25m radius) will be long enough to keep spin rates at 4rpm or below for Mars equivalent G (not ideal of course, but sufficient). The issue (and ongoing argument across many of these threads) has been about having an internal structure that needs to be reconfigurable for zero-G, upside-down and right-way up operations. Having a dedicated cruise phase starship that would be able to just do nose down spin G helps this issue too.Mike, I think you are correct. For the first few flights to Mars, early pioneers will have to put up with a higher rate of spin and its coriolis effects to achieve artificial gravity at 0.38g to Mars. Returning to Earth this way may be problematic for their health because they would not be in good shape to tolerate Earth 1.0g.As far as I can tell, this is not a solved problem in either NASA or SpaceX quarters.When we start getting paid passengers for the Mars trip it may be time to consider my approach to achieve a more comfortable and healthful passage.Has anyone shown what the effects of any gravity between 0 and 1g would do to the human body long term?Are we building hypothetical ship designs on assumptions.
Quote from: Ionmars on 09/20/2022 11:46 amQuote from: RamsesBic on 09/20/2022 11:35 am......Has anyone shown what the effects of any gravity between 0 and 1g would do to the human body long term?Are we building hypothetical ship designs on assumptions.We have experience with missions at ISS in essentially zero gravity. Returning after 6 months astronauts are still alive, but not much more. We do not have experience at 0.38g, which is better than ISS but would be for longer duration, at least two years between synods. Some of these conditions are not feasible to simulate on Earth.You exaggerate. Polyakov demonstrated 437 days and walked out of his Soyuz.
Ask yourself for how long did he walk? Long enough to take some photos, or was it longer? It only proves he can endure a lot, that's all.I was wondering if anyone did a test with humans living at say 0.3g for months then returning to 1g? To my knowledge no one has. Do we even know if 0.1 g is not enough to be fine after a few days adjusting?I am astounded by the lack of any tests done during the last 50 years. It has only been 0g for all those years - and extrapolations.
Quote from: RamsesBic on 09/20/2022 01:44 pmAsk yourself for how long did he walk? Long enough to take some photos, or was it longer? It only proves he can endure a lot, that's all.I was wondering if anyone did a test with humans living at say 0.3g for months then returning to 1g? To my knowledge no one has. Do we even know if 0.1 g is not enough to be fine after a few days adjusting?I am astounded by the lack of any tests done during the last 50 years. It has only been 0g for all those years - and extrapolations.Polyakov is also a sample size of one. The eye damage is particularly serious and currently irreversible.JAXA actually did some 1/6g experiments in their mouse habitat in 2020 but have never published any results. It's extremely frustrating.
Quote from: RamsesBic on 09/20/2022 01:44 pmAsk yourself for how long did he walk? Long enough to take some photos, or was it longer? It only proves he can endure a lot, that's all.I was wondering if anyone did a test with humans living at say 0.3g for months then returning to 1g? To my knowledge no one has. Do we even know if 0.1 g is not enough to be fine after a few days adjusting?I am astounded by the lack of any tests done during the last 50 years. It has only been 0g for all those years - and extrapolations.Polyakov is also a sample size of one.
The eye damage is particularly serious and currently irreversible.
JAXA actually did some 1/6g experiments in their mouse habitat in 2020 but have never published any results. It's extremely frustrating.
I was wondering if anyone did a test with humans living at say 0.3g for months then returning to 1g? To my knowledge no one has. Do we even know if 0.1 g is not enough to be fine after a few days adjusting?I am astounded by the lack of any tests done during the last 50 years. It has only been 0g for all those years - and extrapolations.