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It's the year 2050, and you're the planner for a manned mission to Pluto - New New Horizons.

The mission will take 5 years round trip, and there are 40 members of the crew. What's the most efficient way to feed them all, keeping in mind safety margins and contingencies? Efficiency is measured by the amount of mass you need (less is better).

Your astronauts need at least 2,000 calories a day, and a varied diet - if you make them eat nothing but rice they will mutiny and ruin the mission. They come from various nationalities, so you should try and have food for all walks of life.

Why Pluto/Charon - Advanced analysis of New Horizon photography reveals evidence of likely artificial structures around ~2040 (think of something not obvious from any single photograph, but from a statistical computer analysis of all of them). This is also why they don't have existing bases or outposts - this is a recent push.

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    $\begingroup$ Why would they make a push for Pluto/Charon with a infrastructure essentially no different from today? There should be bases or outposts elsewhere already, and mature technologies. A continuous-boost drive like an ion drive would cut the trip time substantially from just-plain-coasting, so 15 years for a single trip doesn't wash. If it's an extended exploration they will have supply runs. $\endgroup$ – JDługosz Jul 25 '15 at 8:49
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    $\begingroup$ Given the high-school physics relation $ x=1/2 a t^2$ with a half way distance of 1.5 billion miles, and a of 2 milli-newtons, that is a total trip time (1 way) of 1 year. Invest in an ion drive before packing so much provisioning. $\endgroup$ – JDługosz Jul 25 '15 at 9:00
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    $\begingroup$ So this may be off topic, but every time I read the title I read "how to cook forty humans." My answers may not be immediately applicable to your question... then again.... $\endgroup$ – Cort Ammon Jul 25 '15 at 15:18
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    $\begingroup$ @CortAmmon: it was intentional on my part, question title is based off of simpsonswiki.com/wiki/How_to_Cook_for_Forty_Humans which does something similar. $\endgroup$ – Dan Smolinske Jul 25 '15 at 16:07
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    $\begingroup$ I read this title as "How to cook forty humans." LOL $\endgroup$ – Ethan Bierlein Jul 25 '15 at 17:22
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Print It

3D Printing of food is right around the corner. As an additive process, your astronauts would plug in what they want to eat, and your printer will create it out of layering and fusing granules together in order to prepare your food for you.

Downside/Upside

The tricky part is that most likely by 2050 technology, the food produced will be very dry, requiring a hydration process. Still, the space requirement for this much food + water for hydration will be dramatically less than today. For example, we know astronauts don't eat bread, because it takes up too much room (and crumbles after a while). Now they can make and eat bread, or let them eat cake.

Requirements

Food

An astronaut is provided three meals a day. I am speculating that an average "meal" is only 50% efficient in size; that is to say, it's 50% air and water, just by looking at MREs, or imagining breads, pastas, and sauces. Others will be shipped as-is, such as condiments.

Therefore a meal that would be transported via (even vacuum sealed) box can be 50% smaller as granules for printing. A tight meal box measuring 150cm3 can now be 75cm3.

  • 75cm3 x 3 meals x 40pax x 5475 days = ~50 cubic meters of storage.
  • Water requirement (additional 25%?) = ~3 cubic meters of water (for food hydration only).
  • Contingency and Miscellany (additional 20%?) = ~2 cubic meters of space.

Drink

Next your astronauts need water, juices, and please let them have at least some alcohol if they're going to be stuck together for 15 years.

If we follow the 2l of hydration per day, this translates to 2,000cm3 per day.

  • 2,000cm3 x 40pax x 5475days = 438 cubic meters of space.
  • Contingency (20%) = 88 cubic meters of space.

All of the contingency should include delivery space, space for your astronauts to collect it, your printer (and backup printers!), and any spillage or spoilage.

Total = 580 cubic meters of space. Your walk-in storage hall could be 2m high, 2m wide, and 145m long. You can store the champagne and glasses "overhead" or "below the walkway" presuming you have gravity.

But, wait, there's more.

Consider a percentage reduction by using the materials in poop (sorry) and recycled urine (sorry), to reduce the space requirements for feeding your 40.

Benchmarking

I ran a restaurant for two years, and a days' worth of food for 40 people could easily be squished into 9000 cubic centimeters, so my numbers might even be too high. Feel free to replace any of the assumptions and percentages to design your space craft.

But, why?

I am keen to understand why on Earth you want to prioritize Pluto in our space program in the next 35 years.

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  • $\begingroup$ Edited for math and removed liquids, thanks. $\endgroup$ – Mikey Jul 25 '15 at 13:58
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A replicator will 3-d print whatever you want out of basic food molecules, based on stored templates and the crew's imaginations.

There is no way to make such a trip without something approaching this level of technology. Either the old fashioned way (farming) or with high-tech shortcuts, atoms must be reused and not stocked for one-time use.

The low end of the technology would be to eat slidge from a vat. In-between is to take the vat products (yeasts and algae) and generate textured protein, fats, sugar, etc. and put those together in some artistic ways, helped along with some herb gardens.

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American MREs are approximately 0.5 kg per 1,000 calories. That means stored food for each astronaut would be approximately 5 tons (assuming a similar composition).

  • Can you build a lighter hydroponic garden system?
  • What if you have to include double or triple redundancy?
  • What is the risk that the ecosphere collapses?
  • Where are you getting the air, and are there synergy effects with basic food production?

I think a significant part of your supplies will be carried in cargo. Perhaps there is a hydroponic garden to produce oxygen, recycle shit, and grow fresh lettuce, but it won't produce a sustainable ecosphere for 40 people.

The food supply will need a low water content and a good shelf life in refrigerated storage.

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  • $\begingroup$ You do not need an ecosystem/sphere, just farming facilities for the people. The concept of ecosystem is that it is self-regulated; an hydroponic farm is vey intensively managed by outside forces (robots/humans); in the same way that modern farms need fertilizers, insecticides, lots of human and mechanical work, etc. $\endgroup$ – SJuan76 Jul 25 '15 at 11:57
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A Closed Loop system is possible by extrapolating from today's technology. Waste such as table scraps, "grey" and "black" water is fed into a device called a Super Critical Water Oxidizer (SCWO), where it is broken down under tremendous heat and pressure into its constituent molecules. The resulting water stream can be sent into algae tanks, hydroponic farms or even used as the basis for aquaculture, providing a large quantity of food and oxygen for the crew.

The SCWO is a pretty important piece of machinery, so there will be at least two for redundancy during the trip. Since the SCWO is running at 200 atm pressure and the fluid is heated to over 300 C, the engineering support will be focused on the efficient function of the device and prevention of failures. Other areas of concern would be the manifolds, to ensure the smooth flow, pressurization and depressurization of the fluid, heat exchangers to reduce energy consumption and monitoring the entire system to ensure there is no corrosion or blockages in the system.

As mentioned, a 15 year trip seems a bit excessive, especially if they use high ISP drives like Ion thrusters or VASMIR, and of course if they are using a nuclear powered ship (fission or fusion) then they have plenty of energy to run the SCWO, as well as carry a warehouse full of freeze dried emergency rations.

For that matter, there is no reason the space agency sending the expedition can't send out smaller, lighter craft full of supplies to establish "cache" points along the way (the smaller spacecraft is sent on a trajectory calculated to bring it close to the main ship at time "x" and makes the final approach much like a SpaceX Dragon bringing supplies to the ISS). A bit of complicated orbital mechanics would be needed (many ships would have to be launched well ahead of the exploration ship to be in the proper place at the proper time and at the proper velocity, for example), and of course another supply depot ship should be sent in advance to be at Pluto once the main ship arrives.

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  • $\begingroup$ Unmanned supply ships can be sent at >> 1g accelerations, so it is easily conceivable that there will be plenty of robotic and supply support that is 'post-faxed' as it were, sent after the fleshy-sack-ship left Earth Orbit $\endgroup$ – Serban Tanasa Jul 26 '15 at 10:33
  • $\begingroup$ While possible, the issue there would be matching velocity with the exploration ship. Your plan might work as a means of sending supplies directly to Pluto and establishing a cache there, with the caveat that you need to bring along enough fuel to slow down once you reach Pluto. $\endgroup$ – Thucydides Jul 26 '15 at 14:31

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