|
|
Thread Tools | Display Modes |
#31
|
|||
|
|||
"Allen Thomson" :
Ian Stirling wrote: The claim is basically rubbish. No, freeze-dried stuff may not have all of the nutrients it once did ten years out, or be quite as tasty. I checked on MREs and the Army's nutrition lab says that they're nutritionally good beyond 10 years if held unfrozen at 15 C (60 degrees 'murkin). So I agree, the claim that a few-year mission couldn't get along on preserved food plus some supplements looks pretty odd. If you can haul it, of course, but it isn't clear where the mass of a closed or semi-closed system becomes significantly less than that of a fridge full of high-tech TV dinner equivalents. And there are issues of reliability, power, contamination associated with a veggie garden in space, let alone an escargot ranch. See, another problem. Escargot? When you could be growing shrimp, crabs and lobsters? What a waste. Earl Colby Pottinger -- I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos, SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to the time? http://webhome.idirect.com/~earlcp |
#32
|
|||
|
|||
John Schilling wrote:
"Allen Thomson" writes: Ian Stirling wrote: The claim is basically rubbish. No, freeze-dried stuff may not have all of the nutrients it once did ten years out, or be quite as tasty. I checked on MREs and the Army's nutrition lab says that they're nutritionally good beyond 10 years if held unfrozen at 15 C (60 degrees 'murkin). So I agree, the claim that a few-year mission couldn't get along on preserved food plus some supplements looks pretty odd. The Army's nutrition lab also says that MREs, new or old, are nutritionally *bad* if they are the entirety of one's diet for more than a few weeks. If you believe the Army, you can't just And how many tens of millions of people would get better nutrition eating only MREs? For a mars trip, if an orbiter is part of the scheme, it's not horribly difficult to keep a freezer at 100K for the duration. Dehydrated food stored at 100K, some frozen luxuries, and multivitamins. Get some chefs in to compete and produce dishes that taste nice, or at least not too horrible. (100K is arbitrary, I could not quickly find any reference to food nutritional values stored at low temps for long periods) |
#33
|
|||
|
|||
John Schilling wrote: "Allen Thomson" writes: I checked on MREs and the Army's nutrition lab says that they're nutritionally good beyond 10 years if held unfrozen at 15 C (60 degrees 'murkin). So I agree, the claim that a few-year mission couldn't get along on preserved food plus some supplements looks pretty odd. The Army's nutrition lab also says that MREs, new or old, are nutritionally *bad* if they are the entirety of one's diet for more than a few weeks. If you believe the Army, you can't just stock your Mars ship with a three-year supply of MREs and imagine the problem has been solved. Er, I used the MREs as an example of the preservability of food while retaining whatever nutritional virtue it started out with. In the case of MREs, that virtue seems to be considerable, if not long-term adequate. However, the viewgraph that started this seemed to say that the state of the art isn't here for preserving nutritionally adequate food for multi-year Mars missions. So is there some ingredient of a multi-year nutritionally complete diet that can't be preserved by chilling or freezing or dehydration or whatever? If so, what might it be? |
#34
|
|||
|
|||
Derek Lyons wrote:
Earl Colby Pottinger wrote: To me it sounds like some at NASA is fishing for more money instead of storing dehydrated at low temperatures. Right. And the only evidence introduced to date that NASA is wrong is the marketing hyperbole of survivalist websites. Well, it's not all getting posted, but I spent a while looking into this when I first did the One Way to Mars mission architecture back in 1996. I have the actual DOD MRE lifetime specs somewhere. Below 60F, they can be made to last arbitrarily long. Long before you get to liquid nitrogen, MRE and equivalently well packed other storable food will last longer than a human lifetime. Merely keeping them within 5 degrees of freezing is plenty. The specifics of why the DOD recommends you not eat MREs and only MREs for several years have to do with the design of the MRE itself not inherent to long term usage of stored food. The MRE is intended to be a combat ration and to be blunt, grossly overnourishes troops if they're eating the recommended quantity per day. US troops are going into the field and getting fat *in combat* eating MREs these days, a phenomenon previously unheard of in wartime logistics of any era. Their specs for field food prep and environmental condition survival are also extreme as are their ability to be produced by the tens of millions of units. People could theoretically survive adequately on beef jerky and vitamin pills for some years. Though I am not volunteering to be the guinea pig for that one, I think it illustrates the magnitude of how well solved this problem is. There is also a huge difference between needing to be able to grow or have fresh supplies of *everything*, and having a few fresh items which are supplements to a storable base diet. For example, a few strawberries greatly liven up a breakfast or lunch which otherwise is essentially infinitely storable. Or a fresh tomato. Very small addons which are known to be amenable to hydroponics and zero-G cultivation will give taste and texture boosts and largely overcome stored food monotony. I did joke in my presentation at Case for Mars IV that one of the reasons to leave the Lifetime expedition crew there was that if they came back, they might track me down and strangle me for having send them out there with stored food for all that time. But all joking aside, this is not nearly the problem that it's being made out to be. I have never known an ECLSS nutritionist in the last ten years who didn't believe that storable was an entirely practical option. I have also never met an astronaut or astronaut candidate who would seriously reject going on a Mars mission just because the meals for six years were going to be MRE quality. I am wondering if we're seeing a partial repeat of the Bush(41) NASA "all roads to doing anything on Mars must pass through my personal fiefdom" problem. The specifics of the claim on the roadmap presentation defy extensive research and the community consensus within the ECLSS community as far as I have been able to ascertain, and this point directly bears on the validity of One Way missions so I have been asking around and researching it. In my specifically fairly educated opinion, the statements on pp 21 of the human studies powerpoint are not well founded and should not be taken as accurate. If the authors of that document would like to back it up with some additional research which contradicts the institutional assumptions which have been in place for at least the last 10 years then they should feel free to, but baldly asserting that it's true is not reasonable. -george william herbert |
#35
|
|||
|
|||
John Schilling wrote:
"Allen Thomson" writes: Ian Stirling wrote: The claim is basically rubbish. No, freeze-dried stuff may not have all of the nutrients it once did ten years out, or be quite as tasty. I checked on MREs and the Army's nutrition lab says that they're nutritionally good beyond 10 years if held unfrozen at 15 C (60 degrees 'murkin). So I agree, the claim that a few-year mission couldn't get along on preserved food plus some supplements looks pretty odd. The Army's nutrition lab also says that MREs, new or old, are nutritionally *bad* if they are the entirety of one's diet for more than a few weeks. If you believe the Army, you can't just stock your Mars ship with a three-year supply of MREs and imagine the problem has been solved. This is a function of the particulars of the MRE food loadout, not of "equivalent to MRE technology stored food systems in general". MRE is a useful simplification of what one would really want to do, but in reality it wouldn't be anything exactly like a whole bunch of pallets of DOD standard MRE units. The MRE particulars are the proof by demonstration, not the actual final implimentation. Final implimentation will almost certainly make use of a lot more well frozen food and stuff that you just can't reasonably do for field MRE use and field MRE volume requirements. Deep frozen meat and some veggies are obvious, deep frozen fruit in some cases easy in some not, and for some types of fruits and veggies it looks like they just don't store well and won't be on the menu. I wonder how well sushi does in LN2... -george william herbert |
#36
|
|||
|
|||
Allen Thomson wrote:
However, the viewgraph that started this seemed to say that the state of the art isn't here for preserving nutritionally adequate food for multi-year Mars missions. So is there some ingredient of a multi-year nutritionally complete diet that can't be preserved by chilling or freezing or dehydration or whatever? If so, what might it be? I second this question, as my decade of research before and after the One Way to Mars lifetime mission proposal says that the space nutrition community consensus is an overwhelming "storage is fine" and directly contradicts that slide. -george william herbert |
#38
|
|||
|
|||
Michael Smith wrote:
On Wed, 23 Feb 2005 01:09:42 +0000 (UTC) Sander Vesik wrote: Dried fish and meat keeps for years, especially so in cold weather. Now as for not getting scurvy, you need a way to make vitamin C stay around. Concentrated vitamin C tablets are readily available now. I would expect that you could get away with a source of carbohydrate and protein, combined with food additives in tablet form. Yes, but they have limited keeping times - certainly limited to that of dried fish and meat, though.. I don't exct that to be problem wither. But of course, in realty, most humans eat un unbalanced and unhealthy (in way too many ways) diet. Only a small minority manage to develop serious problems over the timeline of a couple of years. More importantly, simulation studies are quite easy to carry out down here on Earth. Its a classical case of way over-complicating and way over-engineering something just because of "space". Why should the astronauts eat way more healily up there than down here? -- Sander +++ Out of cheese error +++ |
#39
|
|||
|
|||
Ian Stirling wrote:
Dehydrated food stored at 100K, some frozen luxuries, and multivitamins. Get some chefs in to compete and produce dishes that taste nice, or at least not too horrible. (100K is arbitrary, I could not quickly find any reference to food nutritional values stored at low temps for long periods) Well, we know at the very least that mammoth stored in permafrost for thousands of years was edible and didn't cause any undesirable side effects. Unfortunately there were no nutrionists in existence back then. Given that AFAIK there is at least one un-melted carcass in teh hands of Russian Academy of sciences, finding out what happens to meat nutitionaly over such long period of time might not be impossible. -- Sander +++ Out of cheese error +++ |
#40
|
|||
|
|||
"Paul F. Dietz" wrote in message ... Michael Smith wrote: Correct me if I am wrong, but I can't see anybody supporting the development of nuclear rocket engines, given the political problems associated with simple RTGs. Why should this follow? RTGs are much more radioactive at launch than are reactors. Because those who oppose RTGs most loudly aren't exactly dealing with rational arguments to begin with. The bigger problem with space reactors is development cost and lack of application. Paul |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Multiple crashes running Boinc/seti last 3 days | Arthur Kimes | SETI | 13 | August 30th 04 03:50 AM |
Multiple crashes undering Boinc/seti last 3 days | Arthur Kimes | SETI | 0 | July 5th 04 09:33 PM |
Beyond Linear Cosmology and Hypnotic Theology | Yoda | Misc | 0 | June 30th 04 07:33 PM |
Multiple systems - How are they determined to be multiple? | Chris L Peterson | Amateur Astronomy | 3 | October 6th 03 06:47 AM |
Whats in the sky today | [email protected] | Amateur Astronomy | 3 | July 14th 03 04:24 AM |