Sounds like Linus is Disagreeing with thunderfoot on the hyper loop not agreeing

[subunit]

re: spaceflight for extended periods.

Please see https://www.ncbi.nlm.nih.gov/pubmed/21715682
FASEB J. 2011 Oct;25(10):3646-60. doi: 10.1096/fj.10-177295. Epub 2011 Jun 29.

Interesting, but hindlimb unloading for 2 weeks at the earth's surface is not even vaguely comparable to 6-9 months in zero g. You'll also notice that the paper includes zero micro-CT structural data which is pretty much de rigeur for this kind of work. Even if it's possible to maintain BMD with some small molecule supplement (very unlikely over the required timeframe- the gene regulatory networks you're perturbing in order to produce increased osteoblast differentiation will densensitize), what matters for the actual load-bearing properties of bone is the microstructure, not the mass. Correct load-bearing microstructure is produced by bearing loads- the osteocytes which are directing osteoblasts to plate out bone are effectively strain gauges. If all you're doing is keeping osteoblasts active and osteoclasts quiescent, you'll keep bone mass, but you're not necessarily going to get an effective load-bearing structure.

[cdev]

Yes, that makes sense.

So "intermittent" is likely what is optimal. I have a number of supplements I take in an on for several days or weeks, off for several days or weeks cycle.

 this kind of learning is still very much ongoing. It may be useful in osteoporosis too. Seems like it is.

[mtdoc]

Wolff's Law

Ain't no med or supplement gonna do it.

[subunit]

this kind of learning is still very much ongoing. It may be useful in osteoporosis too. Seems like it is.

It is, in fact, osteoporosis research in microgravity research drag. There is close to zero money for basic bone research, the two main granting streams are osteoporosis/penia and microgravity stuff, so lots of cash-strapped osteoporosis labs will write up microgravity grants to get access to that cash. This is evident in the paper you linked- published in FASEB, using techniques that were considered dated years before publication, etc.

Wolff's Law

Ain't no med or supplement gonna do it.

Yeah, any solution is almost certain to be mechanical. I remember seeing some interesting stuff about loading bedridden patients' legs with some kind of vibrating platform. Something like that might cut down on the overall size of the craft you need to build- maybe you only need to spin it up to .3g or something if you can get the crew on a vibrating platform for a couple hours a day. Either way, the basic operational problem NASA identified is nowhere near solved, and the quantity of resources required to deal with it is totally unknown. Astronauts are notoriously resistant to the notion that they should submit themselves for post-mission sacrifice and autopsy, and with essentially no funding on the basic side of things, this is unlikely to change by 2024.

[Fungus]

I used to work on bone remodelling, and once had the opportunity to speak to a NASA bone guy about Mars missions. He unequivocally stated that the trip was too long with any plausible near-future rocketry to maintain enough bone density (which is lost relatively quickly in micro/low-g) for the astronauts to have unbroken limbs, rib cages etc. when subjected to the landing deceleration.

And I'm not sure why everybody assumes he hasn't talked to that exact same NASA bone guy.

A possible solution would be to build a craft large enough that you could spin it for centrifugal gravity without causing everyone to puke constantly

So there is a known solution to the problem.

but this would almost certainly require orbital assembly, massively increasing the cost of the mission. None of the proposed craft I've seen are big enough.

Either that, or ... two small craft joined together with a long piece of string.

I'm not sure why anyone takes Musk very seriously.

Maybe because of his history of doing the "impossible".

[Kjelt]

Just build a capsule for one human and launch it into a net a few hundred miles away, proven technology since the 19th century and small infra structure needed 

https://en.m.wikipedia.org/wiki/Human_cannonball

[subunit]

I used to work on bone remodelling, and once had the opportunity to speak to a NASA bone guy about Mars missions. He unequivocally stated that the trip was too long with any plausible near-future rocketry to maintain enough bone density (which is lost relatively quickly in micro/low-g) for the astronauts to have unbroken limbs, rib cages etc. when subjected to the landing deceleration.

And I'm not sure why everybody assumes he hasn't talked to that exact same NASA bone guy.

A possible solution would be to build a craft large enough that you could spin it for centrifugal gravity without causing everyone to puke constantly

So there is a known solution to the problem.

but this would almost certainly require orbital assembly, massively increasing the cost of the mission. None of the proposed craft I've seen are big enough.

Either that, or ... two small craft joined together with a long piece of string.

In other words, an upscaled, orbitally assembled Tempo3, requiring years of prototyping and testing, rather than what SpaceX actually announced?

I'm not sure why anyone takes Musk very seriously.

Maybe because of his history of doing the "impossible".

I don't think anyone considered online payments, solar panels, or electric cars to be impossible before Elon Musk got into them. He's been very successful at pursuing ventures that are good candidates for government subsidies and the like, but it's a bizarre kind of Great Man theory to think that somehow trumps decades of institutional experience built up by the only organisations with actual operational experience with long term manned spaceflight.

[Fungus]

Either that, or ... two small craft joined together with a long piece of string.

In other words, an upscaled, orbitally assembled Tempo3, requiring years of prototyping and testing

Yep. It's quite an old idea for dealing with microgravity without building something the size of a city. Perfectly sound in principle  and already used in many movies.

rather than what SpaceX actually announced?

I think SpaceX announced a three month journey. That system wouldn't be necessary for a three month journey, no.

Here's the thing: They're allowed to change their designs/plans at any time, just like Hyperloop.

I really don't know why people bother going over the fine details of "engineering plans" which are really just artists impressions for press release purposes.

Maybe because of his history of doing the "impossible".

I don't think anyone considered solar panels, or electric cars to be impossible before Elon Musk got into them.

A lot of people said they'd never work out financially.

(...and a lot of people are still saying that, despite the half million pre-orders on the latest car, etc.)

I'm not an Elon Musk fanboy by any means but I am on a Hyperloop team so I know first hand that there's a huge gap between what the press is printing and what people are actually building behind the scenes.

[EEVblog]

All engineering is a compromise between what you would like to do and what can be done efficiently.  Hyperloop is one of those experiments where you try to take away the main drawback with a design, and then see what other problems that creates. A big problem with fast vehicles is air resistance, so the idea is take away the air, then see how that affects the design.

Definitely.
And right there the Hyperloop should have never left the back of the envelope.
Any competent systems design engineer with any sort of sense of commercial and practical reality should have just considered that 1000km of several meters wide vacuum tube and went NOPE, let's try some other way.

Yet look what we have ended up with. This concept being taken as and almost given, countless people and all of the media talking as if it's just a few years away when practically no real enigneering has been done at all on solving the major problem with the concept. It's an embarrassment to engineering.

Compare that to say Space-X. There was a little bit of hype when Musk announced working on reusable rockets, yet it wasn't until full scale tests were happening that people went crazy about it. Hyperloop is arse-backwards.

[Fungus]

Yet look what we have ended up with. This concept being taken as and almost given, countless people and all of the media talking as if it's just a few years away when practically no real enigneering has been done at all on solving the major problem with the concept. It's an embarrassment to engineering.

Is there any difference at all between Hyperloop and uBeam?

[mtdoc]

practically no real enigneering has been done at all on solving the major problem with the concept.

Could you explain how you know this?

[Beamin]

I imagine the people would have to take a lot of things to preserve the bone loss like drugs similar to HGH and testosterone; probably even for females. People going to mars would probably be significantly chemically altered and I'm sure the ones that come back would have permeant health problems and risk of cancer from radiation.

[Kjelt]

Mars is a one way ticket, they can not bring enough fuel for the return journey.
Even then there were alot of volunteers to go, five minutes of fame but when they arrive they might have second thoughts while aur and water is running out and they take the suicide pill.

[orion242]

Richard Branson now tosses an untold sum into hyperpoop.

https://techcrunch.com/2017/10/12/hyperloop-one-becomes-virgin-hyperloop-one-with-virgin-group-investment/

[R005T3r]

I just don't care about the hyperloop anymore: the US goverment/investors are  foolish enought to invest into that? I certanly doubt it!

Anyway, 

[T3sl4co1l]

Wow, SpaceX gets a huge break.  They conned the majority of their liability off on someone else.

Tim

[Z80]

An 'article' by the BBC on Branson's joining the circus.  Most of it is just cringe worthy, un-researched bandwagon jumping sound bytes. 
http://www.bbc.co.uk/news/technology-41595297
There is an interesting statement by hyperloop one's Josh Giegel though:

The combination of our proven technology and Virgin's expertise in transportation, operations, safety and passenger experience will accelerate the commercialisation phase of our company's development

.
  Proven technology, well they are keeping that a well guarded secret, all they have shown are laughable student projects. 

[EEVblog]

Mars is a one way ticket, they can not bring enough fuel for the return journey.

Err, making fuel on Mars isn't hard. Several groups already have working systems.

[EEVblog]

Is there any difference at all between Hyperloop and uBeam?

Yes. uBeam got the world's best acoustic experts to work for them, Hyperloop has, what, student contests?

[Kjelt]

Mars is a one way ticket, they can not bring enough fuel for the return journey.

Err, making fuel on Mars isn't hard. Several groups already have working systems.

Then why does NASA not buy this tech instead of still trying to work things out as they stated last july
http://www.wired.co.uk/article/nasa-rocket-fuel-mars

Then there are many  other problems/challenges : oxygen, cosmic radiation causing cancer, boredom , psychology and we can continue.
The biggest question: what is the point to go to Mars? It is not that there is an alien race we want to meet and start diplomatic relations.
It is cool as a young boys dream but it costs billions of $ and serves zero practical use. The reason we build boats and explore the earth was that we gained more than it cost and it was unknown territory. Mars is well known , well explored and mapped but we haven't put a human on its surface.
I rather wished the world would spent it on practical use as discover new cures, new energy sources, higher crop productivity, influence the weather, distribute fresh water over the planet so people will not die from thirst or hunger etc.

[Fungus]

Is there any difference at all between Hyperloop and uBeam?

Yes. uBeam got the world's best acoustic experts to work for them, Hyperloop has, what, student contests?

uBeam is (now) a deliberate con game, milking VCs for all they can get.

Hyperloop may be frivolous but it has a few "Plan B"s and right now the students are learning some real engineering (and quite a bit of marketing, too - our students have to go around trying to scrounge money from big companies).

[EEVblog]

Is there any difference at all between Hyperloop and uBeam?

Yes. uBeam got the world's best acoustic experts to work for them, Hyperloop has, what, student contests?

uBeam is (now) a deliberate con game, milking VCs for all they can get.

Hyperloop may be frivolous but it has a few "Plan B"s and right now the students are learning some real engineering (and quite a bit of marketing, too - our students have to go around trying to scrounge money from big companies).

Well, to be fair, uBeam could have had a Plan B too and pivoted the idea to niche markets.

Hyperloop will have to pivot too of course, the vacuum parts of it is just plain real world impractical and any team with any clue will quickly come to realise this if they are serious about moving to real full scale testing of something.

[EEVblog]

I rather wished the world would spent it on practical use as discover new cures, new energy sources, higher crop productivity, influence the weather, distribute fresh water over the planet so people will not die from thirst or hunger etc.

Or simply spend slightly less on new military toys and go to mars instead with the leftover change, and you know, re-ignite the dreams of an entire new generation, which, you know, kinda makes life worth living...

[T3sl4co1l]

Heh, here's a thought:

If hyperloop takes off, imagine how many turbopumps will be manufactured.  Just for a short path.

The cost of production will plummet, making high vacuum applications cheaper in general.

And, when hyperloop inevitably crashes and burns, all those massive turbopumps will be sold off for pennies on the dollar.  Ever wanted a vacuum chamber the size of your house, but too afraid to pump it down?  Just wait a few years.

Tim

[Beamin]

Is there any difference at all between Hyperloop and uBeam?

Yes. uBeam got the world's best acoustic experts to work for them, Hyperloop has, what, student contests?

Dude didn't you see the RC car go like 60mph at almost 100 meters? Who do I make the check out to?