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Running multiple HET in parallel?



 
 
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  #21  
Old February 22nd 05, 04:54 PM
Earl Colby Pottinger
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"Allen Thomson" :

I don't know enough about long-term nutrition and related
matters to have an opinion, but note that the manned-Mars
presentation at the recent Mars roadmap meeting contains
the following assertions at slide 21:

http://www.hq.nasa.gov/office/apio/p...an_studies.ppt

Closing the life-support air and water loops with low
expendables is a key leveraging technology for long
duration human exploration missions

Current food preservation technology is not capable of
providing nutritionally viable food for the longer
mission durations under study. Food production
technologies under the environmental conditions of these
missions is not developed to the point of being the
primary source of food.


This reads like an out and out lie to me. Water storage is basicly forever.
But all the end-of-the-world nuts and people who just want long term safety
incase of a major national problem have been buying freeze-dried, canned,
sealed and stored in extra cold freezer food that is rated for 5-7-even 10
years storage. And that is just goe average calling a local dealer.

A quick google search using 'long term food storage' gives me for example:
http://waltonfeed.com/self/deh-veg.html

To me it sounds like some at NASA is fishing for more money instead of
storing dehydrated at low temperatures.

Earl Colby Pottinger

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  #22  
Old February 22nd 05, 06:12 PM
Ian Stirling
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Jan Vorbr?ggen wrote:
Current food preservation technology is not capable of
providing nutritionally viable food for the longer
mission durations under study.


I wonder...didn't some of the early Artic and Antarctic expeditions
go several years without resupply?


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.
However, add a couple of Kg/year of supplements, and you can live on
practically anything that has enough calories.

No, it may not taste as nice 20 years down the line.

And that's without talking about cryogenic freezing of foods, which may
be almost trivial in some cases, where you've got lots of vacuum and shadow,
the sky is 3K.

If food can take -20C for 6 months, then at -200C, it's going to last for
over a century.
  #23  
Old February 23rd 05, 02:09 AM
Sander Vesik
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Jan Vorbr?ggen wrote:
Current food preservation technology is not capable of
providing nutritionally viable food for the longer
mission durations under study.


I wonder...didn't some of the early Artic and Antarctic expeditions
go several years without resupply?


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.


Jan


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Sander

+++ Out of cheese error +++
  #24  
Old February 23rd 05, 07:20 AM
John Schilling
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Earl Colby Pottinger writes:

"Allen Thomson" :


I don't know enough about long-term nutrition and related
matters to have an opinion, but note that the manned-Mars
presentation at the recent Mars roadmap meeting contains
the following assertions at slide 21:


http://www.hq.nasa.gov/office/apio/p...an_studies.ppt


Closing the life-support air and water loops with low
expendables is a key leveraging technology for long
duration human exploration missions


Current food preservation technology is not capable of
providing nutritionally viable food for the longer
mission durations under study. Food production
technologies under the environmental conditions of these
missions is not developed to the point of being the
primary source of food.


This reads like an out and out lie to me. Water storage is basicly forever.
But all the end-of-the-world nuts and people who just want long term safety
incase of a major national problem have been buying freeze-dried, canned,
sealed and stored in extra cold freezer food that is rated for 5-7-even 10
years storage. And that is just goe average calling a local dealer.



"Rated", by people who have nothing to lose by making the rating on account
of there won't be any courts left in which to sue them if the scenario in
which their product's performance will ever be tested, actually occurs.

More generally, the people who actually eat five-year-old stored food are
not the ones who have kept scientifically vigorous records of the storage
conditions and then conduct detailed analysis of the present nutritional
balance of the food and the performance of the people exclusively eating
that food. And the people who do study the issue with that degree of
rigor, generally have a funding cycle of less than five years.

NASA is right in that there is very little in the way of food with a
*proven* shelf life of five years, and what there is (MREs, lifeboat
rations, and the like) is known to be not healthy if eaten exclusively
for years on end.

This is not to say that it would be terribly hard to do the tests and
find a suitable assortment of off-the-shelf items for the job. NASA
would almost certainly overdo it, but it *does* take more than just
stocking up on Walton's and Mountain House and whatnot and hoping you
don't find out the hard way that the universe has a surprise in store
for you.


Having the first crew of astronauts to reach Mars, slowly die from
malnutrition, on live television, on the return trip, would be Really
Bad for A: the astronauts, B: NASA or whomever else is running the
mission, and C: the future of human spaceflight in general. It's
going to take us more than five years to build the ships; we can
afford to take five years to properly test the provisions.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
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  #25  
Old February 23rd 05, 03:11 PM
Henry Spencer
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In article ,
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.


As others have noted, cryogenic refrigeration is going to thoroughly halt
any deterioration in stored food, vitamins, etc.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |
  #26  
Old February 23rd 05, 10:40 PM
Allen Thomson
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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.

  #27  
Old February 24th 05, 08:41 AM
John Schilling
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"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.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *

  #28  
Old February 24th 05, 09:25 AM
Derek Lyons
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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.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL
  #29  
Old February 24th 05, 10:51 AM
Michael Smith
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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.
--
Michael Smith
Network Applications
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  #30  
Old February 24th 05, 11:06 AM
Michael Smith
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On Fri, 18 Feb 2005 20:04:20 +1100
Malcolm Street wrote:

I'm a great fan of Stephen Baxter, but his novel "Voyage" really
doesn't do the NERVA nuclear-thermal rocket program justice; it was
both saner and more successful than he makes out.


So am I. IMHO the books he has written which explore the current or near
future space program have a more realistic idea of what is possible than
just about anything I have read. Yes the bit in Voyage about the Nerva
did somewhat put me off the idea.

| Of course the problem was that bits of engine
| got spat out the back as well, but it was acceptable by '60's
| standards. Of course you'd have to be more careful now.

The real problem is that it is a partly open loop system. No other
nuclear power system routinely exhausts significant quantities of
radioactive material. I agree that a modern system would have to be more
careful but I think this would take the design back to the drawing
board.
--
Michael Smith
Network Applications
www.netapps.com.au | +61 (0) 416 062 898
Web Hosting | Internet Services
 




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