Author Topic: Nose tethered BFS Spaceships for artificial gravity during the coastal phase.  (Read 15339 times)

Offline Aussie_Space_Nut

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Offline corneliussulla

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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

Offline Paul451

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Also if you spin up the ships would mean the solar arrays would then need to withstand partial G forces.

It could make deployment easier, since the (presumably thin-film arrays) wouldn't need a stabilising structure to deploy them, they'd just unroll and "hang", then be rolled back up before despin and landing.

Offline Negan

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Also if you spin up the ships would mean the solar arrays would then need to withstand partial G forces.

I don't see how the arrays could be so flimsy as to not be able to handle this. The arrays will have to be deployed and retracted hundreds of times during the ship's lifetime.
« Last Edit: 10/16/2017 10:05 PM by Negan »

Offline Coastal Ron

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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.

During his recent AMA on Reddit Musk said it was to keep the propellant from boiling, since the tanks are not pressurized.

Quote
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

As currently designed the solar panels would not operate properly if two BFS were connected via their noses and spun.

Also, I'm not sure anyone knows if there are structural attachments at the nose - which if there isn't then there isn't much to discuss...  :o
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Offline envy887

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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.

During his recent AMA on Reddit Musk said it was to keep the propellant from boiling, since the tanks are not pressurized.

Quote
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

As currently designed the solar panels would not operate properly if two BFS were connected via their noses and spun.

Also, I'm not sure anyone knows if there are structural attachments at the nose - which if there isn't then there isn't much to discuss...  :o

It's a convenient place to lift for vertical integration at the pad, which is required if the booster lands on and stays on the pad.

Offline intrepidpursuit

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Apollo astronauts reported that the capsule was barely livable in long duration tests on the ground, but much more spacious in freefall. Anyone landing on mars will be in space 3-6 months and then on mars for 18+ months. Gravity during the flight will cause more harm than good imo.

Offline mikelepage

Interesting article in part on the effects of living in a low g environment log term.

https://www.brisbanetimes.com.au/world/north-america/astronaut-scott-kelly-on-the-devastating-effects-of-a-year-in-space-20170922-gyn9iw.html

Apollo astronauts reported that the capsule was barely livable in long duration tests on the ground, but much more spacious in freefall. Anyone landing on mars will be in space 3-6 months and then on mars for 18+ months. Gravity during the flight will cause more harm than good imo.

Worth reading the Scott Kelly article above if you haven't already.  He describes the return to Earth after 340 days as being okay for the first 24-48 hours followed by systemic pain, bloating and rashes that were "much, much worse" than after his 6-month stint.  Then "A few months after arriving back on Earth, though, I feel distinctly better."

So what I take from that is that adjusting back to life at 1xg after a year at zero gravity is a very severe ordeal.  It takes at least twice as long as adjusting to zero gravity in the first place, and unless Mars gravity is sufficient to reverse all the effects of zero/partial gravity, there's a good chance the astronaut will die upon return to Earth. 

At the very least, it would be worth having some facility/tethered-BFS's in LEO where returning astronauts can be gradually acclimatised back to 1xg rather than returned to the surface immediately.

Offline intrepidpursuit

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Interesting article in part on the effects of living in a low g environment log term.

https://www.brisbanetimes.com.au/world/north-america/astronaut-scott-kelly-on-the-devastating-effects-of-a-year-in-space-20170922-gyn9iw.html

Apollo astronauts reported that the capsule was barely livable in long duration tests on the ground, but much more spacious in freefall. Anyone landing on mars will be in space 3-6 months and then on mars for 18+ months. Gravity during the flight will cause more harm than good imo.

Worth reading the Scott Kelly article above if you haven't already.  He describes the return to Earth after 340 days as being okay for the first 24-48 hours followed by systemic pain, bloating and rashes that were "much, much worse" than after his 6-month stint.  Then "A few months after arriving back on Earth, though, I feel distinctly better."

So what I take from that is that adjusting back to life at 1xg after a year at zero gravity is a very severe ordeal.  It takes at least twice as long as adjusting to zero gravity in the first place, and unless Mars gravity is sufficient to reverse all the effects of zero/partial gravity, there's a good chance the astronaut will die upon return to Earth. 

At the very least, it would be worth having some facility/tethered-BFS's in LEO where returning astronauts can be gradually acclimatised back to 1xg rather than returned to the surface immediately.

By that logic having gravity on BFS is even worse because colonists will be going through this painful adjustment period and possible death while in transit. Much better to deal with that on earth.

Offline whitelancer64

*snip* there's a good chance the astronaut will die upon return to Earth.  *snip*

[Citation Needed]
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Offline Peter.Colin

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Interesting article in part on the effects of living in a low g environment log term.

https://www.brisbanetimes.com.au/world/north-america/astronaut-scott-kelly-on-the-devastating-effects-of-a-year-in-space-20170922-gyn9iw.html

Apollo astronauts reported that the capsule was barely livable in long duration tests on the ground, but much more spacious in freefall. Anyone landing on mars will be in space 3-6 months and then on mars for 18+ months. Gravity during the flight will cause more harm than good imo.

Worth reading the Scott Kelly article above if you haven't already.  He describes the return to Earth after 340 days as being okay for the first 24-48 hours followed by systemic pain, bloating and rashes that were "much, much worse" than after his 6-month stint.  Then "A few months after arriving back on Earth, though, I feel distinctly better."

So what I take from that is that adjusting back to life at 1xg after a year at zero gravity is a very severe ordeal.  It takes at least twice as long as adjusting to zero gravity in the first place, and unless Mars gravity is sufficient to reverse all the effects of zero/partial gravity, there's a good chance the astronaut will die upon return to Earth. 

At the very least, it would be worth having some facility/tethered-BFS's in LEO where returning astronauts can be gradually acclimatised back to 1xg rather than returned to the surface immediately.

By that logic having gravity on BFS is even worse because colonists will be going through this painful adjustment period and possible death while in transit. Much better to deal with that on earth.

Logic states itís always better from a health perspective to have 0,39 G on the BSF than zero G.

The optimal gravity for health during the different stages of the trips is most likely higher than 0,39 G, and will be dependent on what the effect of Mars gravity has on the human body. That effect is unknown. It could even be that for instance prolonged exposure (years) to 0,8G is more optimal for your health than prolonged exposure to 1G. We just donít know.
« Last Edit: 10/25/2017 05:40 PM by Peter.Colin »

Offline Paul451

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So what I take from that is that adjusting back to life at 1xg after a year at zero gravity is a very severe ordeal.  It takes at least twice as long as adjusting to zero gravity in the first place, and unless Mars gravity is sufficient to reverse all the effects of zero/partial gravity, there's a good chance the astronaut will die upon return to Earth.

I don't think the cumulative damage could ever be enough to kill them. Assuming Musk's preferred 100-and-a-bit day transit time, say 4 months worst case, you have 8 months cumulative zero-g. Bad, but demonstrably not fatal, unless you already had a medical issue (thin heart muscle, etc) which would presumably disqualify you from Mars anyway.

So the only issue is whether Mars gravity provides a restorative effect. And IMO, if it's insufficient to restore health after 4-months zero-g, then it's also likely to result in long term damage to permanent settlers even if they landed healthy. That means no colonies on Mars until there's a SF-level revolution in pharma and/or genetic engineering. (Or any base where you weren't on continuous ISS-like health monitoring and exercise/medication regimes.) Which makes the issue of partial-g during transit redundant anyway. Either time on Mars (plus exercise) can undo the damage of 4mths zero-g, or we aren't going to Mars. I can't see a middle-case.

That doesn't mean that expecting to go straight from 4 months zero-g to active work on Mars isn't an issue, and that even partial-g during transit wouldn't be useful, but there's a big jump from "it's an issue" to "it's fatal". [Aside from accidents. Passing out during an EVA (from combined orthostatic hypotension, hypovolemia, and the loss of Vasovagal response) is not going to make you happy.]



Aside: Out of curiosity, what's the shortest time before an astronaut has reflown after, say, more than a month of micro-g? (Ie, more than Apollo/Gemini/STS/etc.) Have NASA or the Russians ever tried the experiment of flying an astronaut for a standard tour on Mir/ISS (say, 3 or 6 months), then bring them home for a short recovery period, then send them back for another tour of the same length, to look at whether damage is worse on the second tour, even though nominal health at launch was the same in each case.

Interesting to think about the BFS crew (not colonists) who are flying a regular schedule back and forth. How often can they fly. How many trips before cumulative damage (from micro-g and/or radiation) ends their career?

Offline envy887

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Paul, what makes you think that crew will make many or even multiple trips?

Offline Paul451

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Paul, what makes you think that crew will make many or even multiple trips?

Passengers will generally make one trip (with some returns.) But crew is crew. It's their job.

If you can only send them once (ie, two trips, out and return), then you have to hire/train entirely new crew for every synod. If Musk can achieve the colonist numbers he imagines, there's going to be a bunch of ships every trip, that's a lot of crew to replace each time, and a lot of experience wasted. Therefore it seems reasonable to assume the crew will fly as many times as medical standards allow.

Has something been said by Musk to suggest one-time only crews?

Online guckyfan

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Has something been said by Musk to suggest one-time only crews?

Nothing has been said to suggest crew at all. Some people on board will need some training to run life support and kitchen facilities. But many of the passengers being highly qualified there is no reason there would be no one of them qualified. The ship and its flight functions will not need any crew as most flights will be unmanned.

Offline mikelepage

*snip* there's a good chance the astronaut will die upon return to Earth.  *snip*

[Citation Needed]

That was in response to intrepidpursuit's timeline of 3-6 month transit + 18 month Mars stay + 3-6 month transit.

I was at the microgravity research symposium at IAC2017, with plenty of NASA, European and Russian medical researchers present.  While everyone thought a flags-and-footprints (~<12 months?) mission to Mars and back was plausible and within the envelope of human endurance, spin-gravity was mentioned multiple times as the only solution anyone can think of for going longer without even more severe symptoms.  The cumulative effects of extended microgravity do not appear to stabilise after any time point so far documented in humans or rodents.

One of the NASA researchers was particularly pessimistic regarding anything less than 1xG - she was the one demonstrating up to 50% reduction in bone mass of rodents spending only 37 days on the ISS.  Her suspicion was that even those astronauts who are retaining bone mass and density due to exercise regimes - would still have considerable bone remodelling similar to the rats in the experiments.  This means more osteoarthritic symptoms, and specifically, a huge increase in the amount of the dense, brittle "cortical" bone that normally makes up the surface of bone, and a massive reduction in the mesh-like "tribecular" bone that normally fills the main body of the bone.  This means you can maintain the same average bone density even as large voids open up in the main structure, and results in a bone that is far more brittle than before.   Obviously time will tell as the current generation of astronauts grows older, but I think it's a bit crazy not to be seriously exploring solutions now. 

I don't think the cumulative damage could ever be enough to kill them. 
Obviously I do  :P  Some astronauts who had been off world for years could end up in an interesting conundrum if they develop a condition that means they need to come back to Earth surface for treatment, but the gravity makes it an impossibility.  Spin gravity could be the only current-technology solution.


Offline philw1776

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Has something been said by Musk to suggest one-time only crews?

Nothing has been said to suggest crew at all. Some people on board will need some training to run life support and kitchen facilities. But many of the passengers being highly qualified there is no reason there would be no one of them qualified. The ship and its flight functions will not need any crew as most flights will be unmanned.

Precisely.  At least for the first crewed synods a significant portion of the passengers will be technically adept.  Some number of them will have specific training to maintain environmental systems, etc.  Sadly including toilet maintenance.  I see no need for pilots, navigators, etc. on a BFS.  Automation in the 2020s or 2030s is only going to be better than today where all SpaceX flights are successfully automated.
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Offline WindyCity

So what I take from that is that adjusting back to life at 1xg after a year at zero gravity is a very severe ordeal.  It takes at least twice as long as adjusting to zero gravity in the first place, and unless Mars gravity is sufficient to reverse all the effects of zero/partial gravity, there's a good chance the astronaut will die upon return to Earth.
So the only issue is whether Mars gravity provides a restorative effect. And IMO, if it's insufficient to restore health after 4-months zero-g, then it's also likely to result in long term damage to permanent settlers even if they landed healthy. That means no colonies on Mars until there's a SF-level revolution in pharma and/or genetic engineering. (Or any base where you weren't on continuous ISS-like health monitoring and exercise/medication regimes.) Which makes the issue of partial-g during transit redundant anyway. Either time on Mars (plus exercise) can undo the damage of 4mths zero-g, or we aren't going to Mars. I can't see a middle-case.

How about centrifuging on Mars? Regular exposure to 1 G in a centrifuge might provide a sufficient prophylactic against the ill effects of long-term low-G exposure.
« Last Edit: 10/26/2017 10:56 PM by WindyCity »

Offline Lars-J

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How about centrifuging on Mars? Regular exposure to 1 G in a centrifuge might provide a sufficient prophylactic against the ill effects of long-term low-G exposure.

If there are ill effects of Mars gravity, something like that could be done. But we just don't know yet. Long term ill effects in the entire span between 0 G and 1 G is an unknown. But we'll only know by trying.

Offline Aussie_Space_Nut

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Interesting article in part on the effects of living in a low g environment log term.

https://www.brisbanetimes.com.au/world/north-america/astronaut-scott-kelly-on-the-devastating-effects-of-a-year-in-space-20170922-gyn9iw.html

Apollo astronauts reported that the capsule was barely livable in long duration tests on the ground, but much more spacious in freefall. Anyone landing on mars will be in space 3-6 months and then on mars for 18+ months. Gravity during the flight will cause more harm than good imo.

Worth reading the Scott Kelly article above if you haven't already.  He describes the return to Earth after 340 days as being okay for the first 24-48 hours followed by systemic pain, bloating and rashes that were "much, much worse" than after his 6-month stint.  Then "A few months after arriving back on Earth, though, I feel distinctly better."

So what I take from that is that adjusting back to life at 1xg after a year at zero gravity is a very severe ordeal.  It takes at least twice as long as adjusting to zero gravity in the first place, and unless Mars gravity is sufficient to reverse all the effects of zero/partial gravity, there's a good chance the astronaut will die upon return to Earth. 

At the very least, it would be worth having some facility/tethered-BFS's in LEO where returning astronauts can be gradually acclimatised back to 1xg rather than returned to the surface immediately.

By that logic having gravity on BFS is even worse because colonists will be going through this painful adjustment period and possible death while in transit. Much better to deal with that on earth.

Logic states itís always better from a health perspective to have 0,39 G on the BSF than zero G.

The optimal gravity for health during the different stages of the trips is most likely higher than 0,39 G, and will be dependent on what the effect of Mars gravity has on the human body. That effect is unknown. It could even be that for instance prolonged exposure (years) to 0,8G is more optimal for your health than prolonged exposure to 1G. We just donít know.

My simple thought is we need an AG staion in LEO to test all this before we go too far.

However if people insist on just going for it I think the easiest on the human body idea would be as follows.

2 Spaceships tetherd together at Earth spin up to 1g.

On the way to Mars they slowly spin down to 0.38g for their arrival at Mars.

On the way back do the reverse. This would give the body time to adjust.

Will this work? I have no idea!  :)

That is why we need an AG station in LEO to test this stuff out.

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