DeepSeaBase

Bioreactor tubes are stackable because biomass production doesn't fall-off as fast as solar productivity does in less light. The fresnel lens just enhances the irradiance for the entire stack of tubes or wherever its target happens to be. Your question gives me an idea though. The Bioreactor module, if was taller, could have walls that fold down when landed that contain mirrors, and the mirrors can shine up to the bottom of a higher stack. In this way the higher stack is illumined from below which if you think of those solar concentrators on the roof, that below target can be hit and funnel light (by mirror probably) into a lower stack. Depends on if it's worth it to stack the modules. For your statement though it was in reference to the amount of tubes that can be packed into a space. You can stack more and have effectively up to 2 or 3x the tubes on a square meter footprint and still not lose too much. The entire 'window' of the module would be the lens.

So my post that is researched and has sources and logical arguments gets downvoted? What's up with that?

TL:DR Your mind will be blown. Bioreactor/diesel blows Solar out of the water. Bioreactor is approximately 5x more efficient than Solar Panels optimized for Mars. WITHOUT additional efficiency modifiers that can be applied to Bioreactors. Same area of flat bioreactor as Solar Farm (50km^2) = power for 277 astronauts. Bioreactor makes rocket fuel (solar panels do not). Bioreactor is modular and can be built on Earth and shipped to Mars. Bioreactor uses in-situ materials, solar panels cannot. Bioreactor recycles all its nutrients/materials. Bioreactor provides numerous other benefits to Astronauts. So my first thread raised a lot of good questions, I want to attempt to answer them properly. The main questions are: How can this be more efficient than solar? How can it be provided for? Nutrients, offworld elements, etc? How can it operate? Basically it comes down to this: is a bioreactor more efficient and practical than a solar farm or some radiogenic method, etc? I say yes for the following reasons. First, why did I retitle this from "biodiesel"? Because I'm not sold on the closed-cycle diesel generator. There is an even better ethanol fuel cell that is a potential power source that uses elements easily extracted from Martian Regolith to act as the catalyst. So first: technologies used. Photobioreactor - https://www.researchgate.net/publication/318031436_Photobioreactors_for_the_production_of_microalgae Direct Ethanol Fuel Cell - https://en.wikipedia.org/wiki/Direct-ethanol_fuel_cell Or a Closed Cycle Diesel Generator - https://en.wikipedia.org/wiki/Air-independent_propulsion#Closed-cycle_diesel_engines Measurement of success? Generate power on a better scale than solar at less weight-cost than uranium using in situ materials if possible. K, let's get started. So the photobioreactor comes in many forms but its efficiency comes in its space savings and modular design. The module can be pre-built on Earth and shipped to Mars, an advantage to any set-up requiring more labor-intensive construction. Tubular Serpentine Photobioreactors with linear-fresnel lens solar concentrators will be the probable type of photobioreactor used to accomplish biomass production. Why? Because the linear-fresnel lenses will greatly improve efficiency. Such devices theoretically could be used to enhance solar panels, but the weight of a panel is higher than an empty tube and again, not modular or compact and can't be stacked (unlike bioreactors which can stack). The important part of this is dry mass - an acre of open ponds of algae produces at most about 10 grams of algae per day per m^2 footprint. Comparatively - the photobioreactors without additional equipment (such as the fresnel lens) produce 22 grams per liter per day. Key Facts 20 m^2 = 1 gallon of fuel per day. Fuel can be biodiesel (a methyl ester) or ethanol. fresnel lens increases solar irradiance by 3.5x more than enough to make up for Mars's lower insolation. For simplicity I'll keep to 1 gallon a day of either fuel type per 20 m^2. Therefore the module would be roughly a 5m x 5m module and can be constructed on Earth and shipped ready to operate on Mars. How much energy does 1 gallon produce? Roughly speaking you can get 10 kwh's per gallon of diesel. https://energyeducation.ca/encyclopedia/Diesel_generator Key Facts Diesel engine produces approximately 10kwh's per gallon of diesel. 2.4 Gallons of fuel per Martian Day per 1kwh stead load. 2.4 Modules or round up to 3 modules fueling a diesel engine. How does this stack-up with the Martian energy requirements? Not sure...so I'll use this as a source: https://planete-mars.com/a-mars-colony-a-tentative-technical-analysis/8/ 90KW per person or 3.75kwh per person. We can get 1 kwh from 2.4 modules so this conveniently works out to 9 modules. Situation so far I did not stack the modules, so we are going with a short footprint of flat modules, with 20m^2 footprints. If the modules are built upward you can greatly reduce this footprint further. Rough calculation are 180 m^2 per astronaut on Mars. Based on others' statements I've seen 50,000m^2 for solar panels quoted for a base of unknown number of astronauts. But... bioreactor modules using closed cycle diesel can provide for 277 astronauts with the equivalent footprint. What about ethanol fuel cells? There are strains of algae that excrete ethanol and other chemical processes can extract ethanol. So how much energy is produced by an ethanol fuel cell? Source: https://energiforskmedia.blob.core.windows.net/media/18529/direct-ethanol-fuel-cells-ethanol-for-our-future-fuel-cells-energiforskrapport-2015-137.pdf Direct Ethanol Fuel Cells produce 6.4 kwh of electricity per liter. Again a gallon is approximately 4 liters, so 1 gallon per day = approximately 1kwh of electricity. The advantage with direct ethanol fuel cells comes from the materials and the lack of complicated oxidizers for closed cycle diesel engines. These Direct Ethanol Fuel Cells use Iron, Nickel and Cobalt for their catalyst and those can be pulled from the Martian Regolith in sufficient quantity if needed to be replaced or repaired. Key Facts: Direct Ethanol Fuel Cells are not much more efficient than the Diesel Generator. In-situ materials. I'd say the ethanol fuel cell therefore could be more advantageous, but its power consideration comes from how much ethanol versus diesel per biomass can be generated. CONCLUSION My conclusion so far is that basically the bioreactor can provide for 277 Astronauts if it were the size of the solar farm. I don't even want to bother explaining all the other benefits of having a bioreactor, and it's a given that all the materials for the bioreactor are recyclable while the bioreactor converts CO2 into O2 which gives you HALF of your return home fuel requirements. Furthermore - the bioreactor can in fact make METHANE. Dare I say...BOOM *mic drop* NOTES: I didn't give the exact figures for Solar panel efficiency, instead I compared solar panel performance on earth to the bioreactor performance on earth and considered it good enough. Since basically the two suffer the same inefficiency problems and wavelength optimizations are possible for both if you consider strains of algae versus materials of solar panels. Source: https://www.theecoexperts.co.uk/solar-panels/how-much-electricity

I don't disagree with what you said except for one point. The US is investing a lot less money into space exploration than China is, and China has advantages afforded its government organized space agency where as you noted the US is devolving its space industry. As such, in the Angry Astronaut video, he points out how little Congress financed the Axios Space Station request that NASA did give. So NASA awarded them an amount and Congress said no. China is full steam ahead. So maybe I should ask a question. Must US government invest more?

China is going to beat the pants off private industry and militarize space. They also have orbited a space plane. So they are now on par with US but way beyond SpaceX or Axios or ULA. Found a very interesting video on Chinese capabilities and where they are headed. Am I mistaken? I thought the whole reason US is giving money to private billionaires is because they will provide a better service than NASA did at securing space. But now you're telling me it doesn't matter they are failing? Why are we paying them then? So billionaires can vacation in space?

I think this "Angry Astronaut" guy makes a great point. Can private industry compete against China? China has basically hit the tarmac with full afterburners and they already have achieved more than SpaceX or Axios combined. US private companies like SpaceX have had some significant accomplishments such as their finally successful re-landing of Starship, but I think time has ran out. China already has equal lift capacity to SpaceX and ULA and Arianne, and they are going bigger. And they are going for a unilateral space station approach which has some very interesting speculative militarization aspects.

I agree, sometimes it's hard for enthusiasts or even industry-professionals to separate the complexities of adding "safety" and "assurance" and stagnation. So often times we get pushed onto timeframes that are unrealistic, or expectations that compromise safety and think of that as progress but really we could have done it better had we remained focused. That's an oversimplification. Just before JFK said that h spent 5 minutes detailing the national security risks of allowing Russia to advance rocket technology while the US remains behind, and made the other point that Russia was poised to militarize space unopposed and the US better seize the opportunity of space exploration before that happens. I see an opposite trend. Test flights have increasing frequencies of failures which is a strong indicator of the manufacturing methods employed. What's happening is the mainstreaming of space. The question is can we tolerate the current hazard levels it is at?

I'm pretty sure that since people can now build computers in minecraft, that can run sizeable programs even, that running these programs in the game still constitutes running a program on the hardware running the game. Therefore that host running the game can be hacked in similar principles to how a host can be used to hack the virtual machines it hosts and vice versa. From me, this is a prediction, not an estimation of how it will be pulled off.

At this point I'm just concerned about the immediate claims. They seem a bit far fetched. I suppose that's OK as long as some progress is made but not at the integrity of the mission. If people get jaded because of tall tales that never turn into anything, then eventually it erodes public support.

We're not having this discussion until you admit that you can't have a $23Billion industry ($23Billion as in profit) unless you earn $5million profit from each seat you sell which works out to 4,600 tourists a year. An absurd number to claim possible in next 10 years, and at current accident rates would kill 460 passengers a year. (I detail this in a thread more appropriate for this whole side of the discussion)

An interesting point developed in another thread but because it's not directly related to that thread I'll just ask the question here and see what discussion forms of it. It fascinates me that NASA actually has asked this question in response to the loss of the Columbia. Brief background, Columbia is just one of many missions that had foam insulation come off the tank and break off tiles. Before whoever throws NASA under the bus, they actually ran through a lot of scenarios to evaluate the tiles and see if the Atlantis should be sent or a jury-rigged repair be made. They determined an unplanned spacewalk is a far higher risk than what had been happening. In hindsight this is now called "normalization and deviance". We normalize recurring mistakes that did not reveal themselves to be mistakes because of no consequence until we deviate so far from a standard that a consequence is probable or certain. K -------------------- having set that aside we can get on with the question of space travel. Is it right to think that risk acceptance is built into space travel? Another way of asking: is it reasonable to think we can accept higher amounts of risk to make it more affordable? I think a lot of us who would love to go into space, I'm certainly one of them, say we would accept a higher tolerance of risk, but when that risk rises above a certain threshold would we really? https://www.intechopen.com/books/into-space-a-journey-of-how-humans-adapt-and-live-in-microgravity/the-mortality-of-space-explorers Let me really start to blow your mind. Astronaut deaths are actually quite high. Job related fatalities are in the 10% range. 1 out of 10 Astronauts are killed by being Astronauts, whether that's training accidents or dying in actual spacecraft related incidents. So where does all this stand? My opinion is that space travel is so infrequent that we as people have no clue how dangerous it really is. Airplane crashes: Chance of death 1 in 5,882,352 https://www.paddleyourownkanoo.com/2020/04/07/the-chance-of-dying-in-a-plane-crash-more-than-halved-last-year-according-to-new-research/#:~:text=IATA concluded that the chance,accident with just one fatality. Car crashes: Chance of death 1 in 103 https://valientemott.com/blog/chances-of-dying-in-a-car-crash/#:~:text=According to the National Safety,crash is 1 in 103. Ok, so let's put that into perspective. If we were sending 4,600 tourists into space at current statistics, 460 of them would die in fatal accidents. These statistics are muted by the fact that Apollo 13 did not end in disaster (took a huge amount of effort to pull that off) and Mir didn't kill everyone on board in a docking accident (3 Astronauts), so we are missing 6 probable deaths from the statistics. ----------------------------------------------------------------------------- I'm not saying we should halt space travel. I'm saying that there's so little of it that we haven't had exposure to how dangerous it really is. As such, people are grossly underestimating that danger. If car crashes were as fatal as space travel then: 365,690 Americans would die each year from driving their car, or almost as many Americans as died in all of WW2. That put into perspective: ---------------------------------------------------------------------------- Can we afford even higher risk to cheapen space flight further for tourism? Can we afford to be complacent? Can we afford to normalize and deviate from already standard practices when the cost is this high already?

How about you address the fact that to achieve $23Billion in revenue at $5million per seat you need to fly 4,600 seats per year. How about you just focus on that absurd prediction and stop hiding behind some non-technical, non-peer reviewed, opinion paper from a bank? That's all I really want you to acknowledge is how do you think space tourism will achieve that kind of lift capacity?

I agree with Tom Booth. It's fine to present observation, in order to understand what went wrong versus our understanding of 2nd law of Thermodynamics, the problem isn't Tom Booth's observation being "speculation" the problem is the thread failed to achieve discovery of the parameters of the experiment. For instance, I'm not sure what the parameters were. So if the thread were to remain open I'd suggest Tom Booth start from the beginning an enumerate the parameters better so we can all review it in a more meaningful way and get to the bottom of it? It's a curiosity and the question can be better asked: "why is Tom Booth's observation wrong?" We know it has to be because none of us are going to stumble on a jackpot world changing discovery in our garage these days. Too many corporate science/engineer stooges already would have found it on their payrolls.

I did some simple math on their own numbers provided. How much networth does someone need to have enough control over their own finances in order to justify a $5million expense? Most wealthy people have powers of attorney in case of accidents who most likely will declare them insane if they want to spend a sizeable chunk of family or estate wealth on a risky venture. If a family has $25million dollars then dad decides to spend $5million, chances are his heirs have enough money to stop him and declare him mentally incapable. You think 3 children want to split $25million or split $20million? So at what point do rich children not have influence over their family's finances. Most families at that level of wealth put their wealth into corporate entities so those entities are even more subject to stakeholders than someone with just $25million in the bank. So I think anyone can identify a number of roadblocks to people throwing $5million at a tourist venture. So even at $5million a seat you have to be very wealthy to do it. And that means 4,600 seats per year. At 10 passengers, that's almost 2 flights a day. What is the turn around of these rockets? Does it take a month? So you need a rolling stock of 60 reentry vehicles and the staff to do 2 per day? I mean come on man, you give me a source, I have the ability to critique the source. The source seems to have ignored everything that actually exists in favor of some fantasy of "well it could happen." I'm going to stand by the idea that no space company currently has the launch ability to send 4,600 seats into space and even then the price of $5million is so high they probably couldn't find enough people to pay that per year. I think suborbital curier makes the most sense for added revenue stream. Vaccines for instance, medical devices, medical materials. Very high value short lived cargo...

Don't be facetious. $23Billion / $50 million = 460 tourists per year. If you lower the cost from $50 million to $5 million then you get 4,600 tourists per year. These numbers are absurd assumptions. Starship, Blue Origins, etc, none of them propose anything that can conduct 460 seats per year let alone 4,600 seats. This is one of those moments where commonsense says whoever the "reputable source is" got paid by the industry to fluff the numbers because no one is going to check them or hold them accountable.