Taber MacCallum: Learned several things from ISS. Ability to assemble systems, and amazing accomplishments, relative to what was though possible decades ago. Environmental control system is current state of the art. Discussing Biosphere 2. Took five months to make a pizza, starting with mating goats to get milk. Had materials and feedstock to build parts as needed. As time went on, had to fight equipment problems. Psychological problems tougher than technical ones, but can be conquered. ISS different kind of complexity, but helps us calibrate ourselves for the technologies needed for space settlement.
We are not ready to do closed-loop life support. Systems too complex, unreliable for remote planetary bodies. need to look at problem at an architectural level. Have to be tested for at least duration of time you plan to be using it for, so for two year mission, need six years lead time, including development. Could be a decade or two before we know if we’ll have a system for surface of the moon or halfway to Mars. If Bobby Braun wants to change the game, need to start doing ground test facilities now, and really go the duration, including people inside for that duration. And this won’t take into account problems of space environment (low gravity, etc.).
“State of the art is we don’t have a fully regenerative system, and it won’t keep working for very long.”
Lee Valentine: Cleaning air is easy, cleaning water is easy, nutritious food is easy with fish. Hard problem is recycling sewage into food. Have to recycle as much waste as possible. Assumptions: gravity is needed, energy by sunlight, 3600 calories per person per day. Big trade in system is biologic fixation (legumes) versus Haber Bosch method.
Aquaculture unit, vermiculture unit (red worms), fungi unit, waste management system. Two-person system would fit into Bigelow Sundancer. BA-2100 obviously much better for testing. Differences from previous systems: water cycle focuses on plants, which need it more, biological design is self designing and self correcting, and optimal nutrition, rather than wheat and potatoes, which is a highly deleterious diet. Recycling nitrogen and carbon the overriding challenge. Need to focus on deadlocked material. Water for food production several times higher than direct human requirements. Handling toxins and contaminants uses initial anaerobic stage (including the production of methane if desired). Worms can be backup food source. (Ewwws from audience). Mushroom culture provides water and humus which can be mixed with regolith for soil.
Hybrid of biological and physicochemical systems appears optimal. Best mix of plant and animal systems remains unknown. Need to think about synthetic biology and not constrain ourselves to existing species.
Start soon, start small (many can be done with minimal equipment), need not have closed atmosphere for most of experiments.
Must find Amish Terrarium! Okay, aside from totally obscure movie quotes I do have this to add: what about radiation?
I’m concerned that a biological closed loop life support system would be too vulnerable to radiation and catastrophic collapse. A mechanized system can break down, true enough, but might be repaired or have a backup that could go into action before the crew dies.
But what happens with a biologic system during a dreaded solar flare event? The crew may escape by hiding in a radiation storm shelter but what about the biologic life support system? Even if the bio system could be restored after such an event, could it be restored quickly enough to keep the crew alive?
I suspect that for spaceflight at least as far out as Mars that mechanical systems with limited recycling (say 90% water) plus significant reserves will be the life support system of choice. While closed loop biological systems will have to compete with ISRU systems for long term surface/subsurface base life support.
Re: “Optimal nutrition” vs. “wheat and potatoes.”
I think you’re going to reach a point where your “optimal nutrition” is going to lower morale enough that people are going to go through your airlocks without wearing suits.
There’s a reason why the military makes a variety of MREs and keeps changing them.
I don’t mean a totally open system, but how about a compromise? Part of the diet is produced on-board, part is brought up from Earth.
Depot fuel, depot food?
Anybody consider inviting the U.S. Navy to this discussion, with their experience with nuclear submarine crews being isolated on 6 month (?) tours?
Or would talking with the evil Pentagon be Politically Incorrect?
We did take as data the composition of MRE’s. Based on the best research, MRE’s are not optimal, but they work well for young healthy people in trying circumstances.
We give great weight also to a diet sufficiently satisfying that people will be happy eating what’s grown, without being bored. For good operational reasons, the US Navy submarine service is careful to make sure meals are diverse and tasty.
It is a hard problem. I do not expect the first successful iteration to be any more than serviceable.
Submariners might make a good choice for mars crew as well. They’re used to the food.