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...
Human-rating is the process of designing, evaluating, and assuring that the total system can safely conduct the required human missions.
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?
Quote from: LMT on 07/25/2018 04:43 amIs 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.
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.
Quote from: mikelepage on 07/25/2018 07:36 amEmphasis 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.
Quote from: QuantumG on 07/25/2018 07:56 amQuote from: mikelepage on 07/25/2018 07:36 amEmphasis 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"...
Quote from: QuantumG on 07/25/2018 07:56 amHuh? 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.
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.
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.
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
I swear, in 100 years they'll think us barbaric for even contemplating Lunar/Mars settlement with zero-G spacecraft.
Quote from: mikelepage on 07/26/2018 04:55 amSuch 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 aboutThere's no doubt that they do - but it's an acceptable risk.
Quote from: mikelepageI 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.
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.
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.
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.
7.1.2 Reduced-gravity countermeasuresSpace 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.
12.8. Artificial GravityMany 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. BackgroundLong-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...