Author Topic: Realistic, near-term, rotating Space Station  (Read 694540 times)

Offline LMT

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Re: Realistic, near-term, rotating Space Station
« Reply #1020 on: 07/25/2018 04:25 am »
The reality of the situation is that Elon Musk is going to Mars, and there will likely be a LOT of people that will volunteer to go - without knowing whether 1/3-G has deleterious effects on the human body...

NASA would like to know, beforehand.  The first tenet of a human-rated system:

Quote
Human-rating is the process of designing, evaluating, and assuring that the total system can safely conduct the required human missions.

Emphasis on "missions".  A spacecraft isn't human-rated unless it's safe for the entirety of its intended missions.

Including, of course, Mars missions.

SpaceX must give NASA that assurance -- assurance extending to "safe recovery of the crew from hazardous situations".  Long-duration evaluation of the gravity hazard, with AG testing of flight- and Mars-g options, would be one component of that assurance.  And as we've seen, ITS AG mods could be modest and affordable.

--

Or skip the evaluation and NASA denies human-rating, and mission support.  Probably others would follow NASA's lead, notably the FAA.

--

Is there any reason to think SpaceX will take that uncharacteristic and unnecessary risk?  If you think there is such reason, do any official SpaceX or NASA statements / publications indicate clearly?
« Last Edit: 07/25/2018 04:35 am by LMT »

Offline QuantumG

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Re: Realistic, near-term, rotating Space Station
« Reply #1021 on: 07/25/2018 04:35 am »
The only question that needs to be answered for partial gravity exposure is the effect on human reproduction - which is not really a NASA concern at all.

Over the years, NASA has made it clear that the real concern for a Mars mission is the full radiation exposure. Partial gravity is assumed to be better than none - but even if it's the same as zero-g the mission duration is assumed to be too short to matter.
Human spaceflight is basically just LARPing now.

Offline LMT

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Re: Realistic, near-term, rotating Space Station
« Reply #1022 on: 07/25/2018 04:43 am »
Over the years, NASA has made it clear that the real concern for a Mars mission is the full radiation exposure. Partial gravity is assumed to be better than none - but even if it's the same as zero-g the mission duration is assumed to be too short to matter.

Is there an official statement, translating your "assumption" into a NASA green-light for human-rating without prior AG test?

Offline QuantumG

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Re: Realistic, near-term, rotating Space Station
« Reply #1023 on: 07/25/2018 04:46 am »
Is there an official statement, translating your "assumption" into a NASA green-light for human-rating without prior AG test?

No, because there's zero interest in AG from NASA.
Human spaceflight is basically just LARPing now.

Offline LMT

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Re: Realistic, near-term, rotating Space Station
« Reply #1024 on: 07/25/2018 05:01 am »
Is there an official statement, translating your "assumption" into a NASA green-light for human-rating without prior AG test?

No, because there's zero interest in AG from NASA.

NASA recently invested in the IMSG Turbolift design, as an option for AG in long-duration missions.   

As seen previously.

Agencies invest in things they have interest in. 


« Last Edit: 07/25/2018 11:37 pm by LMT »

Offline QuantumG

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Re: Realistic, near-term, rotating Space Station
« Reply #1025 on: 07/25/2018 05:10 am »
Right, my bad, "zero" is a bit too specific. NIAC Phase I is the ghetto, but it's not nothing.
Human spaceflight is basically just LARPing now.

Offline mikelepage

Re: Realistic, near-term, rotating Space Station
« Reply #1026 on: 07/25/2018 07:36 am »
The only question that needs to be answered for partial gravity exposure is the effect on human reproduction - which is not really a NASA concern at all.

Over the years, NASA has made it clear that the real concern for a Mars mission is the full radiation exposure. Partial gravity is assumed to be better than none - but even if it's the same as zero-g the mission duration is assumed to be too short to matter.

Emphasis mine, and is not even remotely true.

Worth watching the whole thing - an overview of NASA's human research program by Bill Palowski, although most relevant to this thread is from 34 minutes in:

Offline QuantumG

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Re: Realistic, near-term, rotating Space Station
« Reply #1027 on: 07/25/2018 07:56 am »
Emphasis mine, and is not even remotely true.

Huh? Maybe I wasn't clear... the only risk from altered gravity environment that isn't considered sufficiently mitigated already and that a rotating space station might be considered worthwhile building to investigate, is the effect on human reproduction - and NASA is not yet interested in that question.


Human spaceflight is basically just LARPing now.

Offline mikelepage

Re: Realistic, near-term, rotating Space Station
« Reply #1028 on: 07/25/2018 08:28 am »
Emphasis mine, and is not even remotely true.

Huh? Maybe I wasn't clear... the only risk from altered gravity environment that isn't considered sufficiently mitigated already and that a rotating space station might be considered worthwhile building to investigate, is the effect on human reproduction - and NASA is not yet interested in that question.

Your meaning was clear, but repeating the statement doesn't make it true.

As can be seen in the slide 50 minutes into that talk (screenshot attached), there are a number of other microgravity related symptoms considered for 1 year deep space sorties or longer planetary missions, which are considered either partially or completely uncontrolled, and are marked as "requires mitigation".

These include Spaceflight-induced Intracranial hypertension / Vision alterations (VIIP), renal stone formation, immune system alterations and host-microorganism effects.

So even if you accept the risk from all the other musculoskeletal symptoms over that time period - and note that those risks haven't been mitigated, just accepted because no one has a better solution - there are a number of other symptoms that can still render you useless. 

Offline QuantumG

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Re: Realistic, near-term, rotating Space Station
« Reply #1029 on: 07/25/2018 11:01 am »
Sounds like cotton wool to me.
Human spaceflight is basically just LARPing now.

Offline maryalice

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Re: Realistic, near-term, rotating Space Station
« Reply #1030 on: 07/25/2018 12:18 pm »
Apologies if this has already been mentioned but I think in the long term it will depend on the children
born in space or on Mars. These humans will probably never be able to visit Earth, in one short word , evolution.

Mars (or space), will be their home, how can we miss something we have never experienced (Earth)?

Offline Coastal Ron

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Re: Realistic, near-term, rotating Space Station
« Reply #1031 on: 07/25/2018 02:37 pm »
Emphasis mine, and is not even remotely true.

Huh? Maybe I wasn't clear... the only risk from altered gravity environment that isn't considered sufficiently mitigated already and that a rotating space station might be considered worthwhile building to investigate, is the effect on human reproduction - and NASA is not yet interested in that question.

Your meaning was clear, but repeating the statement doesn't make it true.

As can be seen in the slide 50 minutes into that talk (screenshot attached), there are a number of other microgravity related symptoms considered for 1 year deep space sorties or longer planetary missions, which are considered either partially or completely uncontrolled, and are marked as "requires mitigation"...

I don't want to get in the middle of this conversation, but I do just want to make the observation that while SOME in NASA are concerned about the effects of 0G on the human body, those that actually run NASA and those that fund NASA are not yet concerned about it because the U.S. does not have a near-term need where it would be a factor.

And yes, scientists are always trying to solve problems far into the future, but NASA's future plans, as determined by the politicians that make those plans, don't yet require these problems to be solved.

Not sure if I clarified things or just made the waters less clear...  ;)
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline LMT

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Re: Realistic, near-term, rotating Space Station
« Reply #1032 on: 07/25/2018 03:16 pm »
Huh? Maybe I wasn't clear... the only risk from altered gravity environment that isn't considered sufficiently mitigated already and that a rotating space station might be considered worthwhile building to investigate, is the effect on human reproduction - and NASA is not yet interested in that question.

Your meaning was clear, but repeating the statement doesn't make it true.

And it's good to distinguish personal observation from official statement.

So even if you accept the risk from all the other musculoskeletal symptoms over that time period - and note that those risks haven't been mitigated, just accepted because no one has a better solution - there are a number of other symptoms that can still render you useless.

In the past no practical AG solution was available, e.g. on the ISS.  But with ITS SpaceX can have an AG testing option, perhaps the easiest near-term option for a long-duration 0-1 g test system.  It would seem irrational, at this point, for SpaceX or NASA to passively "just accept" grav-med problems on Mars missions.
« Last Edit: 07/26/2018 02:19 am by LMT »

Offline mikelepage

Re: Realistic, near-term, rotating Space Station
« Reply #1033 on: 07/26/2018 04:55 am »
Sounds like cotton wool to me.

Such is the reaction of many engineers and others trained in the hard sciences.  At times it is quite irritating trying to convince engineer-dominated organisations such as NASA, that the multitude of doctors and medical scientists who have studied this do in fact have a clue what we are talking about - that the biological needs should drive the engineering in this case, and that the engineering problem of creating spin gravity is orders of magnitude easier to solve than the biomedical one of dealing without it. 

I swear, in 100 years they'll think us barbaric for even contemplating Lunar/Mars settlement with zero-G spacecraft.  It's not like we have to invent anything new to do spin gravity.  We just have to be a bit more clever in how we implement a lightweight space centrifuge.

Offline QuantumG

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Re: Realistic, near-term, rotating Space Station
« Reply #1034 on: 07/26/2018 05:02 am »
Such is the reaction of many engineers and others trained in the hard sciences.  At times it is quite irritating trying to convince engineer-dominated organisations such as NASA, that the multitude of doctors and medical scientists who have studied this do in fact have a clue what we are talking about

There's no doubt that they do - but it's an acceptable risk.

Quote from: mikelepage
I swear, in 100 years they'll think us barbaric for even contemplating Lunar/Mars settlement with zero-G spacecraft.

Ahh, there's the disconnect - the trip is quick, the stay is long. Putting effort into mitigating the risk of quick dashes is misplaced. The real question is the partial gravity risks of the surface stay.

Human spaceflight is basically just LARPing now.

Offline mikelepage

Re: Realistic, near-term, rotating Space Station
« Reply #1035 on: 07/26/2018 05:55 am »
Such is the reaction of many engineers and others trained in the hard sciences.  At times it is quite irritating trying to convince engineer-dominated organisations such as NASA, that the multitude of doctors and medical scientists who have studied this do in fact have a clue what we are talking about

There's no doubt that they do - but it's an acceptable risk.
Don't equivocate on what "acceptable" means in this context.  NASA HRP says it's acceptable only for the ~1 year timeframe studied.  For longer periods it isn't considered acceptable and experts recommend further mitigation measures.

Quote
Quote from: mikelepage
I swear, in 100 years they'll think us barbaric for even contemplating Lunar/Mars settlement with zero-G spacecraft.

Ahh, there's the disconnect - the trip is quick, the stay is long. Putting effort into mitigating the risk of quick dashes is misplaced. The real question is the partial gravity risks of the surface stay.

That's not at all a disconnect.  If, as you say, the question is the partial gravity risks of the surface stay (forget pregnancy for now - I'm talking serious health effects over a 1-10 year timeframe), then there is a serious possibility that Mars G won't count for enough, meaning that total mission times will put astronauts into the >1 year timeframes of concern.

If we're talking about risk management, it would be prudent to do some partial gravity testing in LEO, for a fraction of the cost of the Mars program.  It need not even delay the program if powers that be were to take this seriously, as medical experts recommend they do.  The timeline of (for example) cargo BFR being able to take large payloads to LEO cheaply, will necessarily pre-date the timeline of crew BFR putting boots on Mars by at least two years, but probably more like 5 or 10 years.  Plenty of time to get some good human partial-gravity data.

If it turns out that Mars-G isn't acceptable for say, periods of greater than 4 years, then part of the Mars settlement program is putting a partial G station in low Mars orbit, so that astronauts don't have to return to Earth and lose a whole synodic period or more just to get their required dose of higher gravity.  And if we already know how to build it, we've saved a serious amount of time and expense for not that much effort in the long run.

EDIT: Just to clarify, I'm not suggesting the whole Mars program should be halted until the partial-G research is done, but that it could be done as a complement to the program, and because of access to LEO versus Mars surface would likely happen much sooner.
« Last Edit: 07/26/2018 06:04 am by mikelepage »

Offline LMT

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Re: Realistic, near-term, rotating Space Station
« Reply #1036 on: 07/26/2018 03:55 pm »
there's zero interest in AG from NASA.

Right, my bad, "zero" is a bit too specific. NIAC Phase I is the ghetto, but it's not nothing.

What did you mean by "ghetto"?   Were you aware of NASA's investment in Turbolift AG?   

Do you think NASA has "zero interest" in MVP results?  NASA sponsored MVP, so you'd think they have interest.

Offline Asteroza

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Re: Realistic, near-term, rotating Space Station
« Reply #1037 on: 07/26/2018 11:45 pm »
A station with AG to deal with a gravitational body's lack of gravity by itself isn't suitable for infrastructure purposes, because the alternative of a ground centrifuge (modules swung on wires, or a full merry-go-round ring AKA the Circus Maximus solution) is in the end cheaper and more appropriate for supporting surface ops.

The place where an AG has serious merit is wherever somebody is stuck in zero-g for a long time, and to a lesser extent training/acclimatization for transiting passengers. Which basically boils down to long term residence/living/working at a fixed site (depot station, or waypoint gateway), and long transits. Semi-fast transits may cut that market out, at least for travel equal to or less than Mars/Venus. Anything farther will be really long in transit, effectively forcing one to have a mobile station in practice, or very dependent on very high speed transit, which reverts to the zero-g case being acceptable due to short transit time (or the propulsion thrust is high enough to provide a measure of AG itself).

Offline QuantumG

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Re: Realistic, near-term, rotating Space Station
« Reply #1038 on: 07/27/2018 12:01 am »
What did you mean by "ghetto"?   Were you aware of NASA's investment in Turbolift AG?   

$125,000 award. That's called "throwing scraps".

Quote from: LMT
Do you think NASA has "zero interest" in MVP results?  NASA sponsored MVP, so you'd think they have interest.

Biomedical research.

It is now, and has always been, the position of NASA that biomedical mediation of negative partial gravity effects is the preferable solution. Until there's integration of AG into the reference design missions, that's still the case.
Human spaceflight is basically just LARPing now.

Offline LMT

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Re: Realistic, near-term, rotating Space Station
« Reply #1039 on: 07/27/2018 04:19 am »
It is now, and has always been, the position of NASA that biomedical mediation of negative partial gravity effects is the preferable solution. Until there's integration of AG into the reference design missions, that's still the case.

Everyone would prefer low-g biomed solutions, if safe and effective, but Mars mission duration nukes that preference.  As mikelepage put it:

NASA HRP says it's acceptable only for the ~1 year timeframe studied.  For longer periods it isn't considered acceptable and experts recommend further mitigation measures.

He's a biomedical Ph.D. at a spaceflight startup, so you might consider his expert opinion there.

--

NASA's interest in AG is well known, and more serious than your "ghetto" posts insinuate.  Even in 2009 NASA's serious interest was clear, and stated plainly in Mars Design Reference Architecture 5.0 and Mars Design Reference Architecture 5.0 Addendum #2.

Quote
7.1.2 Reduced-gravity countermeasures

Space flight experience has shown that significant physiological changes occur during exposure to reduced gravity; most notably bone mineral loss and architectural changes, muscle atrophy, and cardiac de-conditioning, all of which become more severe without proper countermeasures as the stay-time in space increases. Although these effects could be minimized if crews take certain preventive measures while in space, the problem of developing effective countermeasures to reduced gravity is significant.

The major concern relates to the long transit times to Mars coupled with the demands placed on the crews immediately upon arrival at the martian surface. The baseline transit time to and from Mars is 200 days in zero gravity. Exercise, nutrition, and pharmaceutical countermeasures show promise in controlling the adverse physiological effects of long-duration exposure to reduced gravity. Also, three Mars transit options exist: (1) shorten the outbound and return transit times by using advanced propulsion systems, (2) employ artificial gravity countermeasures within the spacecraft either by providing an on-board centrifuge or by spinning the spacecraft itself, or (3) accept the higher risk involved and proceed with the mission using the best available countermeasures. A zero-g countermeasures program is being conducted on the ISS. Appropriate crew stay-time in orbit, combined with the increase in crew size to six, provides an adequate statistical basis for this vital countermeasure information. In addition, countermeasures that are developed to mitigate the deconditioning effects of microgravity would be used at the lunar outpost and on Mars to maintain crew health and performance in these reduced-gravity environments. Zero-g countermeasures alone may not be sufficient to maintain crew health and performance for a Mars mission, however. Adverse physiological changes due to reduced gravity may be prevented by exposure to some level of artificial gravity, but the specific level of gravity and the minimum effective duration of the exposure that is necessary to prevent deconditioning are not yet known. Although artificial gravity should reduce or eliminate the worst deconditioning effects of living in zero gravity, rotating environments frequently cause undesirable side effects, including disorientation, nausea, fatigue, and disturbances in mood and sleep patterns. If artificial gravity is to be employed, significant research must be done to determine appropriate rotation rates and durations for any artificial gravity countermeasures. The decision on whether artificial gravity must be employed to adequately support crews on their transits to and from Mars, as well as the decision on the necessary gravity level and rotation rate, has significant implications for vehicle design and operations.

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12.8. Artificial Gravity

Many of the currently available human health and performance countermeasures compensate for the lack of terrestrial gravity. An alternative approach to a suite of individual countermeasures is to provide artificial gravity (AG) by spinning all or part of the spacecraft.

Two questions must be answered before deciding whether AG is a viable approach:

- What part of the vehicle will spin?

- What are the physiological responses to different AG protocols?

12.8.1. Background

Long-duration crew health can be improved if efforts are aimed at the prevention of health problems induced by the space flight environment, in particular the reduction in gravity. In some cases, countermeasures can prevent some changes by providing alternative methods to maintaining system homeostasis; however, in many cases, they merely ameliorate the negative effects of changes to the body. Each health problem has its own associated countermeasure.

Some countermeasures induce health and other problems of their own, such as the induction of skin abrasions due to the bungee cords that hold one down on a treadmill; the large number of hours of crew time spent exercising; and the mass, power, volume, and maintenance of equipment. A new, serious health issue (vision impairment and intracranial pressure) has been recently identified and is proving difficult to solve, and this relatively new discovery leads to the concern that there may be other potential health risks that have not yet been discovered.

The root cause of many health issues that arise during space flight is the lack of gravity; therefore, providing acceleration that mimics gravity is a rational approach to preventing many issues from arising. AG should be revisited as a way of preventing the detrimental effects of 0-g, thereby minimizing or eliminating the need for many of the developed countermeasures, as well as the resources (mass, volume, power, crew time, development time, and cost) that are associated with them. Many researchers have long felt that AG is the second-best countermeasure for the space flight risks associated with their discipline. Of course, each risk has a different countermeasure that is 'best' suited for it; thus, the total amount of resources necessary to counter all the risks is significant (see section 12.9 below). Alternatively, having one overarching countermeasure, namely AG provided by rotating all or part of a spacecraft, may result in paying one price for the overhead needed to provide a countermeasure that will address most of the risks associated with space flight.

Furthermore, by ensuring that the crew is fully fit and capable of an EVA upon landing on Mars, it may be likely that more robust mission architectures can be developed, rather than requiring their landing craft to serve as their habitat for a week or two during rehabilitation. The benefits of such an approach could have impacts on the way in which the vehicles are designed, packaged, and launched, as well as in the order in which they are sent to Mars, possibly resulting in less expensive launch vehicles...
« Last Edit: 07/27/2018 04:19 am by LMT »

 

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