MCT Speculation and Discussion Thread 4

[GalacticIntruder]

If you take COTS freeze dried food as an example, you get 1080 servings, which feeds one person 2000 calories per day for 200 days. All of that food only weights around 100kg, minus daily water rations. (which will be 5-10 Liters per person per day)

It is true, that prepared freeze dried meals have SCARY sodium levels. But basic freeze dried bulk staples, like chicken, rice, beans, milk, potatoes, eggs, and other common fruits and vegetables have very little sodium.

[Hotblack Desiato]

..meat can be freeze-dried, but reconstituting it turns it into a slurry.....

I spent a lot of summers of college and grad school working as a wilderness guide. I never had much problem with any kind of freeze dried meat: beef, chicken, ham, shrimp. And I ate a lot of it over the years.

Good to know, never had to deal with this kind of products.

I worked with another type of freeze dried products (mostly before they were dried, sometimes afterwards). Freeze dried hemophilia products. Once bottled and lyophilized, they were stable for a long period of time. Because of the special nature of these proteins, creating processes was very tricky (A good friend created several of those processes).

[nadreck]

I have my own dehydrator (nominally meant for making jerky) but I have used it with a variety of veggies to make up food for backpacking. Basically I often carry pasta and rice, packets of dried veggies, spices and herbs that I have mixed up with specific mains and soups in mind but made with what I consider appropriate levels of salt, shredded hard cheese, olive oil, powdered eggs and then sometimes I bring canned/pouched preserved meats and fish to use with all that. I have been known to make up stuff like linquine and clam sauce, vindaloo shrimp, pasta with meat sauce, wild rice with walnuts and cranberries (used up half the fuel I brought for cooking on that one!). But judicious work drying some of my own ingredients allows me the luxury of having less weight efficient meats/fish. Though I do often bring dried shrimp, and sometimes dried tuna flakes.

My friends have brought army rations (too heavy to carry and calorie wise), campers freeze dried foods (as others have pointed out too much salt in those for me to enjoy any amount of them), one friend brings in a thermos full of raw eggs shelled and puts it in a cool stream or spring at night to keep them cool.

[guckyfan]

I understand NASA requires all the meals to include the full complement of vitamins and minerals at the end of the projected shelf time. They won't consider supplements for that purpose. That will sure drive requirements.

[Umbrella]

ESA recently held a meeting to discuss possible human hibernation:
http://motherboard.vice.com/read/a-brief-history-of-cryosleep
Obviously, that is still fairly speculative technology.  But given the enormous practical burden of carrying large amounts of food/water and handling the resulting huge amount of human waste, it warrants serious consideration for MCT.  Hibernation would also eliminate potential psychological issues, like boredom, in transit.

[mikelepage]

It is stating the obvious IMO that at some point the Mars colony has to account for the system-level reality of growing real food and fully recycling the waste...  Ya know, an ecosystem.

Assuming this much, I think it's useful to ask at what point in time do you start planning for the initial steps to happen?  If you're going to have this discussion, it's also useful not to talk in absolutes, since it's likely even the first missions will at least have some experimental setup designed to produce something which can be consumed, and at the other end of the scale, even centuries from now, there will be some things which cannot be grown on Mars and are still imported from Earth.

Between those two points, theres a t₅₀... at time point at which half the food is grown at Mars, and half is imported.

I think it's likely that if that t₅₀ occurs during the operational lifetime of the MCT (say the next 3 decades), and it's probable that the MCT itself will incorporate a lot of that technology, in which case we can expect the design process would be in progress now.

[Burninate]

ESA recently held a meeting to discuss possible human hibernation:
http://motherboard.vice.com/read/a-brief-history-of-cryosleep
Obviously, that is still fairly speculative technology.  But given the enormous practical burden of carrying large amounts of food/water and handling the resulting huge amount of human waste, it warrants serious consideration for MCT.  Hibernation would also eliminate potential psychological issues, like boredom, in transit.

Hibernation is a dark horse option.  The tiny chance we can get it working multiplied by the huge difference it would make means scaling up a very large space program another 1% looks like a bad investment relative to taking the risk with low-hanging-fruit hibernation research... but it's much, much more speculative than MCT.  It cannot be a critical-path element.

Sci-fi gets exactly three plausible means of interstellar and outer-system spaceflight for biological humans: Hibernation, new-physics FTL or new-physics CoE/CoM breaking engines, and generation ships.  The payoff on hibernation is much, much larger than the payoff on a Mars colony, but the odds of it working are unknowable and only look good relative to the other two options for interstellar spaceeflight.

[Burninate]

It is stating the obvious IMO that at some point the Mars colony has to account for the system-level reality of growing real food and fully recycling the waste...  Ya know, an ecosystem.

Assuming this much, I think it's useful to ask at what point in time do you start planning for the initial steps to happen?  If you're going to have this discussion, it's also useful not to talk in absolutes, since it's likely even the first missions will at least have some experimental setup designed to produce something which can be consumed, and at the other end of the scale, even centuries from now, there will be some things which cannot be grown on Mars and are still imported from Earth.

Between those two points, theres a t₅₀... at time point at which half the food is grown at Mars, and half is imported.

I think it's likely that if that t₅₀ occurs during the operational lifetime of the MCT (say the next 3 decades), and it's probable that the MCT itself will incorporate a lot of that technology, in which case we can expect the design process would be in progress now.

I think Martian agriculture is especially difficult, and will probably not scale to t₅₀ until there are more than 10^6 person-years spent on Mars, and they're in the process of industrializing.

This is a hell of a lot of food sent from Earth, but them's the breaks.  We won't be able to build greenhouses, LEDs, and solar panels from native materials without a large amount of bootstrapping, and I don't think they start to look especially promising to send from Earth, myself.  There's a lot of learning and a lot of adapting and a lot of failed crops to do to get agriculture to the point that Mars can *rely* on it, so even if they do experimental agriculture earlier on, that food won't be mission-critical resources.

[nadreck]

Mars could very quickly get to the point where more than 100% of the mass of food consumed on Mars was grown on Mars, and that should be an early goal along with exporting some of that food as soon as their packaging industry has hits the point where packaging materials are locally sourced.  There would still be food imported from earth, but by the time a serious volume of grains and legumes were produced the human diet on Mars could be, by mass, 80-90% locally sourced, that means producing 20% more than they need is all that is needed to go beyond that 100% I mentioned.  If it turns out that it is difficult to grow grains, legumes, fruit, rabbits, chickens, fish, etc in zero G then for a long time there will be a market for Mars produce for micro gravity outposts/expeditions and ones that have yet to develop the CHON ISRU to support their own food cultivation.

[Robotbeat]

There are other threads where agriculture on Mars would fit far better than here. Look in the general Mars section.

[guckyfan]

There are other threads where agriculture on Mars would fit far better than here. Look in the general Mars section.

This is the active thread on those matters. Plenty of interesting posts. Please get the discussion there.

http://forum.nasaspaceflight.com/index.php?topic=35877.0

[Vultur]

Sci-fi gets exactly three plausible means of interstellar and outer-system spaceflight for biological humans: Hibernation, new-physics FTL or new-physics CoE/CoM breaking engines, and generation ships.

Interstellar, maybe, but the outer system is entirely plausible without any of the three. You can do Jupiter and Saturn systems at least with nuclear propulsion.

Now, the habitats would have to be long-term, but not generational. There was a NASA study (HOPE - Human Outer Planets Exploration) which had 4-5 year round trip times for Callisto with NTR and NEP, which are both things we could do with no breakthroughs.

[Robotbeat]

You don't need hibernation. With the propulsion systems in Avatar, the crew could be awake.

Beamed propulsion is a big enabler (not just for light sails... Could be dust accelerators, etc) and requires megastructures to harness Terawatts or Petawatts. You'd also need to brake against the interstellar medium. A refined sort of fusion rocket or fission fragment rocket might be useful in combination with those other things.

Another thing not mentioned: biological immortality. Engineer the human body to not age, or have an ability to replace tissue as needed (3D printer?).

[mikelepage]

There are other threads where agriculture on Mars would fit far better than here. Look in the general Mars section.

This is the active thread on those matters. Plenty of interesting posts. Please get the discussion there.

http://forum.nasaspaceflight.com/index.php?topic=35877.0

Thanks - I hadn't seen that one.

Last q for this thread: I only brought up the Martian agriculture aspect to ask the question about MCT.  The consensus here seems to be that all food for occupants of MCT will be prepared on either Earth or Mars and preserved for travel.  Does that not seem a strange assumption?  i.e. nothing fresh grown on MCT itself? - Granted if "landing the whole thing" is what's happening, then the mass cost of equipment for trying to grow things over periods of 3-6 months probably isn't worth it.  If however there is a part of the architecture that stays in space for years at a time, being reused constantly, then it will be a lot easier to implement some type of long term system.


 

[Geron]

Mayo clinic today announced they eliminated senescent cells in mice and added 35% more useful high quality life.

When this is applied to humans we could be looking at 120 years of useful life.

[Vultur]

Why would an MCT arrive in LEO (with around 200 tons, per Shotwell) packing 50 tons of propellant in place of 50 tons of gear?

I was imagining something significantly more than 50 tons.

What does BFR being too large for any existing pad have to do with it?

Because if I run the rocket equation with 100 tons of payload, dV = 9500 m/s, Raptor's claimed Isp, and dry masses that I consider pretty conservative for SpaceX, I get a rocket that's not that big.

Which suggests to me that the delta-V will be a lot higher - either it'll go to a much higher energy orbit or have quite a bit left.

[philw1776]

Why would an MCT arrive in LEO (with around 200 tons, per Shotwell) packing 50 tons of propellant in place of 50 tons of gear?

I was imagining something significantly more than 50 tons.

What does BFR being too large for any existing pad have to do with it?

Because if I run the rocket equation with 100 tons of payload, dV = 9500 m/s, Raptor's claimed Isp, and dry masses that I consider pretty conservative for SpaceX, I get a rocket that's not that big.

Which suggests to me that the delta-V will be a lot higher - either it'll go to a much higher energy orbit or have quite a bit left.

You are not alone in getting such "not that big" results.  Right now we're all over the map with possibly conflicting  years old Elon statements and crazy big BFR/MCT rumors on Reddit.  But the bottom line is that it does not even take the "mid sized" 15 million LB thrust vehicle to meet the LEO payload claims.

Postponing the architecture announcement for the 3rd time indicates to me that everything is in a high state of flux.  They've likely done some next level of detail of engineering analysis and arrived at some key numbers different than expected, which iterates revisions.  With Musk the decisions will not be just space cadet tech driven but will also have a strong best economic model (as he best believes it) influencing size/capability tradeoffs.

[JamesG123]

No it can't. "Space" isn't cold. It's a vacuum. If you keep your food in an open airlock, it will have the same temperature as any other section of the ship's hull...

But vacuum is a great insulator. All you need is a layer or two of mylar and minimal contact with the hull and your cold stuff will stay cold for a very long time.

Astronauts are crew. Crew morale is important. Colonists are cargo. Only their survival rates matter.

I read that novel too.  But...  Colonists are people. It will only take one going koo-koo to jeopardize everyone and the ship.   

[Stardhingy]

Why would an MCT arrive in LEO (with around 200 tons, per Shotwell) packing 50 tons of propellant in place of 50 tons of gear?

I was imagining something significantly more than 50 tons.

What does BFR being too large for any existing pad have to do with it?

Because if I run the rocket equation with 100 tons of payload, dV = 9500 m/s, Raptor's claimed Isp, and dry masses that I consider pretty conservative for SpaceX, I get a rocket that's not that big.

Which suggests to me that the delta-V will be a lot higher - either it'll go to a much higher energy orbit or have quite a bit left.

Don't forget to save fuel for reuse.

[Robotbeat]

BFR is much more than 100 tons to LEO. That much is clearly established.