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#976 Re: Exploration to Settlement Creation » Settlement design » 2021-04-25 17:26:44
Well I can't research the whole thing again but
"Drugs that prevent bone turnover (loss) have been shown to successfully prevent bone atrophy in both astronauts and animal models in space. "
https://www.nasa.gov/mission_pages/stat … rogravity/
At the same time exercise and pressure-exercise trousers stop muscle wastage.
My understanding is that the wastage for bone and muscle has been coming down for years now and for average stays on the ISS is now at zero. I think some people even gain because of the exercise regimes!
There is a genetic factor in all this - some people are far more susceptible to bone or muscle loss than the average and they need to be screened out as part of the selection process. Whether NASA has developed effective screening as well, I don't know but I wouldn't be surprised if they had.
louis wrote:The bone and muscle loss issue in zero G has been overcome. There are some residual space medicine issue but nothing big enough to prevent a human mission going ahead.
NOT TRUE! There are still serious consequences from prolonged time in microgravity. I worked on a research proposal regarding bone loss regulation about 12 years ago, and there was almost zero interest in my ideas for hormonal regulation of bone loss and sculpting. Only in the past 2 years or possibly 3, has there been a significant uptick in interest.
#977 Re: Life support systems » Trees on Mars » 2021-04-25 17:16:35
Thanks for the links SpaceNut.
Of course trees can be a tremendous food source - fruit and nuts.
But I was thinking on this thread mostly about material usage.
It would be good to get a tree plantation going on Mars within the first 10 years.
100 trees for a 100 person colony could be a great resource.
Industrial robots could use the timber to make a range of products from furniture to bedsteads to bins to shelving and so on.
Interestingly, wood seems to operate well in cryogenic temperatures so it might have some outdoor uses e.g. maybe as the outer body of a night rover.
#978 Life support systems » Trees on Mars » 2021-04-25 16:38:53
- louis
- Replies: 16
Discussion about bamboo - definitely a good crop for Mars but also one that has its limits in terms of uses, prompted me to research trees and tree growth.
Like bamboo, trees are of course good for oxygen production, but could also have many other uses and wood is a more durable material than bamboo.
Some tree species like hybrid poplar can grow 2 metres per annum. So, useful wood supplies could be produced within maybe 3 to 4 years.
I have never heard of growing trees successfully using hydroponics, so I presume soil would either need to be manufactured or imported.
Trees I think do have a psychological benefit for humans as well and give a sense of permanence to a location.
The pioneers might wish to grow trees internally for aesthetic reasons. But as a form of farming, wood would make for a very useful material especially if it is difficult to manufacture metals on Mars. One of the most successful aeroplanes of WW2, the Mosquito, was made of wood.
Wood can of course be used to make furniture and fashion utensils, or as flooring, wall facing etc.
As part of a Materials Development Programme for Mars, both timber and bamboo should be seen as key materials to be produced. Research should be carried out into the best species for Mars. My recommendations would be to focus on fast growing species. On Earth these might be considered uneconomic but on Mars speed is of the essence and the tonnage requirements are low.
In support of this part of a materials development programme a decision would need to be made whether to import the soil or use mainly ISRU to manufacture it on site.
Soil is going to be required for a number of crops and so I think the establishing of a Soil Manufacturing Facility on Mars should be an early goal.
Soil manufacture will require a complex recipe. Rocks will need to be ground down; sand, gravel and clay will be added. The soil will need to be fertilised. Successful plant growth may require the introduction of bacteria and fungi. Space X should really be looking into this in detail already. Taking organisms like fungi and bacteria from Earth to Mars is a big step and the implications need to be addressed.
#979 Re: Exploration to Settlement Creation » Settlement design » 2021-04-25 16:12:27
That link is over 15 years old SpaceNut! Not sure what relevance that could possibly have.
For me the only issue now is whether Space X can safely get their Starships to orbit and to return to Earth. If they can do that on a regular basis then the Mars Mission is definitely on. I can't see much standing in their way. Life Support, suitable habs, developed rovers, solar power systems are all in place. The bone and muscle loss issue in zero G has been overcome. There are some residual space medicine issue but nothing big enough to prevent a human mission going ahead.
Finding and digging out water ice will not be a major issue.
Setting up a propellant plant and getting the return Starship ready to launch are probably the two big challenges.
Musk's available funds are huge and it looks like they are just going to get bigger and bigger as the world converts to electric vehicles and solar power.
tahanson43206 wrote:The third alternative is to decide what is needed, and proceed to make ** that ** happen.
This is what Zubrin's decades and unless you have deep pockets you are not getting any further than waiting.
Nasa Has their plan but its government expensive and is contractor delayed.
Space x Elon has pockets but he has yet to buy or hire the knowledge that will get further.
Currently Nasa has given funding to Space x to produce with assistance but if they balk at any suggestions for what is and will be needed its deal off just as the Red Dragon mission happened.
Job creators exist for many of the proprietary items to come from with granted license from there owners to provide to the buyer but its not a one stop shop that is building the systems of rockets and support that will bring us to Mars.
The plan needs to be broken up into the 3 legs of a mission to mars so as to off load the all in one shot approach that makes it mass limited to the current rockets and even to the starships with its not yet played refueling.
https://nssdc.gsfc.nasa.gov/planetary/m … sretu.html
Current capsules from all vendors can hold with some time limitations the crew of 8 which is pushing it but it can not support the mission to mars and needs more mass than it can hold.
Based on time out going leg is 7- 9 months and with an equal return time of or 120 to 180 days. Planet stay between cycles is surface stay times to a total of 600+ days.
What we still do not have with a Red Dragon design is sufficient mass to surface and a return to orbit capability.
#980 Re: Exploration to Settlement Creation » Settlement design » 2021-04-25 13:17:00
You are underestimating how much NASA/JPL know about Mars. It is in my view extremely unlikely that they will have read the ground conditions wrong for those proposed landing sites. They will have water ice available a few metres at most below the surface. I forget the technical term but basically near those landing sites are hillocks which are regolith over mounds of ice. You can dig through 2-6 metres of regolith and get to very pure ice. The landing sites themselves are firm rock platforms with low dust levels/boulder concentration.
Once a base is established with sufficient water resources and good landing sites, there will be every incentive to return to that location with each new mission because:
(a) That is where there will be functioning habs and functioning energy system
(b) That location will be a known quantity.
(c) There will be Starships there that can be cannibalised for steel, rocket parts and residual fuel.
As the base grows into settlement e.g. with an increasing number of farm habs, a university research unit, leisure coimplex, health facilities and so on, then it becomes even more natural to go to that location and that is where workers and researchers will be needed.
That's not to say it is guaranteed to remain the principal settlement but it has a very good chance of becoming that.
Exploration will of course take place and I can imagine scenarios where things might develop otherwise e.g. if a concentrated source of methane were discovered or a rich location for evidence of life on Mars is found.
I've checked out the Arcadia-Amazonis border before and it seems a good location all round. Other resources like iron ore and basalt are not too far away.
It's much more likely in my view that we will see the tiny base grow and grow into a real city - maybe not the million person city of Musk's dreams but a very sizeable settlement.
Of course that's not to deny other settlements will grow up around a range of resource centres e.g. if we find a good source of carbon or calcium carbonate somewhere, there will be a mining settlement there. Tourism will also be a factor. I am sure there will be a settlement close to Olympus Mons and another at Valles Marineris for instance. Once a network of roadways is established, they will be natural locations for hotels or rover parks (maybe you won't book into a room but just park your pressurised rover in pressurised "hangar" but there will be rest facilities within the "hotel" that you might make use of.
You write:
It may take decades to centuries before the infrastructure can be established to produce those things locally. Steel, concrete-equivalents, etc, come to mind.
I think that is too pessimistic. This will be a new type of colonisation benefitting from things that no previous colonists have enjoyed e.g.
3D printers, CNC lathes, industrial robots, automated production, fetch and carry robots, farm robots, mining robots. Remember as well that this is a virgin planet, as far as we know, and most required resources can be found at the surface. Many elements of something like robotised farming are already in place. Robots are used on farms all over the world for planting, harvesting, crop feed and checking on plant health .
Some ISRU processes such as glass making and steel production could easily be under way within a decade. PV panel production could be established within a decade but will likely be dependent on some imports initially. Within 50 years the Mars settlement may be genuinely capable of self-sufficiency although it is unlikely to seek to achieve that 100%.
The rate of progress will depend to a great extent on how far scaled down factory processes can be made to work well. On Mars "small will be beautiful."
I think this discussion suffers from relatively-undefined terms, as well as an unclear overall goal.
The terms "base" and "outpost" are usually associated with small numbers of people and smallish, temporary housing for them. The term "settlement" is usually associated with substantially-larger numbers of people, housing for all of them, and a sense of permanence. In the extreme, we are talking about cities.
Using those definitions, "settlement" is NOT what you do in the initial landing or landings on Mars (or the moon, or anywhere else). WRONG GOAL!!! You are very far from being ready to do that! You do NOT yet really know "for sure" how to "live off the land". That appropriate-goal lesson is centuries old, even here on Earth. Read your history.
What you do initially is establish a "base" or "outpost" with a small crew, quite probably more than one of them, and try out the techniques and hardware (brought from home) that might possibly enable you to "live off the land".
A lot of those things are just NOT going to work the way you anticipated, if at all, and for a variety of reasons! These include ground truth about resources being divergent from your remote sensing assessments, as well as local conditions different from what you tested back home. Which is why you MUST plan to supply these "bases" or "outposts" from home, on the assumption that your "live off the land" technologies will prove unsuccessful.
Not doing this the right way in the right sequence is why the Roanoke colony failed, and why Jamestown nearly failed. And if you do not get this right on Mars (or the moon, or anywhere else), you WILL kill a crew! Or two. Or more.
Not all these "outposts" or "bases" are going to be successful! Most of them will likely be abandoned for better sites, using better stuff. Maybe all of them. You REALLY need to face up to that very high probability! Which is another reason why "settlement" is the wrong goal for the initial landing. ABSOLUTELY the wrong goal!
None of these "outposts" or "bases" actually need to succeed, as long as you identify (1) where the useful resources really are located, (2) how to successfully obtain them, and (3) how best to use them to "live off the land". That requires exploration of other sites besides the outposts you establish, with those explorations most likely based out of those outposts. You WILL need long distance transportation of some kind! And some sort of mobile habitat to travel along with it, whether part of that transportation or not.
Once you have figured out (1) actually how to "live off the land", (2) what you actually need to accomplish that, and (3) the best site or sites to do it, then (and ONLY then !!!) are you ready to create a (permanent) settlement (or settlements plural). I say "plural", because it is unwise in the extreme to put all your eggs in one basket. Again, read your history to find out why this is a truism. Then learn from it.
Once you have reached the phase where a settlement can be established successfully (by actually knowing "for sure" how and where to "live off the land"), then you no longer need to plan on supplying it basic life support from Earth. But you had better plan on shipping critical materials and technologies from home for some time to come! It may take decades to centuries before the infrastructure can be established to produce those things locally. Steel, concrete-equivalents, etc, come to mind. Lots more.
Such is the history of colonizations, going back centuries, here on Earth. Read it and learn from it. So few do.
GW
#981 Re: Exploration to Settlement Creation » Settlement design » 2021-04-25 05:06:41
Hi Noah,
You might find these links helpful:
1. Potential Starship landing sites on Mars (based on JPL recommendations to Space X).
https://behindtheblack.com/behind-the-b … s-on-mars/
2. A wealth of info to be found in this run-down of a NASA workshop on human landing sites:
https://www.nasa.gov/feature/mars-human … entations/
Thanks Louis and Oldfahrt1939 for your comments.
Thanks RobertDyck and SpaceNut for the sources and informations, looks quite useful.
#982 Re: Home improvements » Vertical Wind Turbine - better than you might think » 2021-04-24 19:49:32
Hmm - that is totally counter intuitive. Assuming a traditional wind turbine design with three horizontal blades, whatever the wind force is doing it's got to push those blades up (against gravitational force) to the 12 o'clock position after which the blades will fall (thanks to gravitational force). Surely the low G makes it easier to get the blade up to the 12 o'clock position.
gravity has nothing to do with how easy it is to move a wind turbine blade. That has to do with force acting on mass, and mass is unaffected by gravity. Doesn't matter which way the turbine axis is oriented, either.
#983 Re: Interplanetary transportation » Aerial phenomena » 2021-04-24 13:40:39
Re the beginning of this thread, there's been some convincing rebuttal of the video's significance, claiming it is a phenomenon associated with night vision equipment where the "eye" of the camera closes over in a triangular shape changing all points of light into apparent triangles whether stars or aeroplanes in the distance. So I no longer this to be a video of interest. The tic tac videos remaining unexplained I think and were also being recorded on radar at the same time.
#984 Re: Home improvements » Vertical Wind Turbine - better than you might think » 2021-04-24 06:06:30
To reiterate I'm not advocating here but I have read a little on the subject. Specifically I saw it stated that the the lower gravity on Mars makes it easier to turn a blade or equivalent. There have been NASA-funded studies suggesting it is feasible. I think they use smaller maglev turbines or something like that.
The other aspect you've overlooked is my specific proposal to create topographical features (narrowing tunnels, mazes, canyons) that increase the gas density and thus wind force. Imagine a circular structure with tapering tunnels or passages, arranged like the spokes of wheel, with an all-directional turbine at the centre. From whichever direction the wind was coming the force would presumably be maximised at the centre.
Louis, the lower gravity of Mars does not increase the kinetic energy in its winds. This is a function of wind speed and air density.
W = 0.5 x n x A x rho x v^3.
Let's say average winds peed of 7m/s and efficiency 40%, which is 80% of the Betz limit. Rho = 0.02kg/m3.
W= 0.5 x 0.4 x 1 x 0.02 x 7^3 = 1.37W/m2 of swept area.
A wind turbine with blade diameter 100m, would generate 10.8kW. Not a good net energy return I would suggest.
#985 Re: Home improvements » Vertical Wind Turbine - better than you might think » 2021-04-23 18:42:58
Keep your hair on, as we say over here. Was only trying to remember and correct the misleading impression being given that wind speed is the main issue.
Whilst your figures are no doubt correct there are two points to be made.
Firstly that atmospheric pressure varies on Mars - there is no sea level equivalent. Hellas Planitia is twice the average.
Secondly the gravity being 38% of Earth's, means the effective ability of the Mars wind to move a turbine is much higher all else being equal (which it isn't, granted). So that would mean that at Hellas Planitia 12.4 mb would in effect be giving you the same force you would get at 32.6 mb - 3.26% of the Earth's atmosphere, 1/30th the strength of the wind on Earth.
I'm certainly not a strong advocate of wind energy on Mars. But it does seem possible that one could do it, maybe using my idea of topograpical focussing of the wind force, which I haven't seen discussed elsewhere to increase the output.
"I seem to recall a figure of the wind force for any given speed being, on Mars, 1/20th of that on Earth and it's wind force, not speed per se that drives turbines."
That "1/20" factor is utter BS. This is rather basic physics. The force on any given element of a blade on a rotating windmill is the wind pressure ("dynamic pressure") times the element area times the element lift coefficient (a number that can be positive or negative depending upon angle of attack), but that peaks at a stall magnitude in the 1 to 1.5 range. The dynamic pressure is 0.5 times density times velocity squared. Blade element drag is similar, but trends differently with angle of attack, and does not peak, it just gets larger and larger.
The two forces element lift and element drag combine to create an axial force and a force tangential to the rotational motion. This is just vector addition, and vector resolution of components, which any person who passed high school physics should understand. You have to integrate (yep, calculus is involved!!) the product of radius and tangential force from hub to tip of each blade, (and sum for all blades), to get the torque of the blading system. There is no difficulty with that, as long as you understand that integral calculus is a way to sum up contributions when the formulas are not simple.
If the blade torque sum exceeds the shaft drag torque sum, the rotation rate accelerates. When it does not, the rotation rate decelerates. There is usually (but not always) a rotation speed where blade torque equals shaft drag torque (the torque required to drive a generator, for example). That is the steady (equilibrium) operating speed for the windmill.
Density on the surface of Mars is 0.007 (0.7%) that on the surface of Earth, typically. For the same wind speed, the wind pressure will be in the same 0.7% ratio to that on Earth, not some 1/20 = 0.05 = 5% that on Earth. You cannot argue with that. For the same distribution of blade twist, the same distribution of blade element angles of attack will exist at the same radius. Thus the same distribution of blade element lift and drag coefficients will exist, along each blade.
If so, then torque on Mars will be 0.7% torque on Earth, all else equal. Not 5% = 1/20 that on Earth.
GW
#986 Re: Exploration to Settlement Creation » Settlement design » 2021-04-23 16:57:26
I was looking into this the other day and it seems like with the ISS LSS, NASA are in a programme of continuous improvement, e.g. finding the best materials for CO2 removal. The impression I got was that they do have systems that work but that they could potentially be improved upon.
Of course a Starship is big enough to take its own air, water and food for a small crew but I am sure Space X will want to put in place something similar to the ISS.
http://www.marsjournal.org/contents/200 … 6_0005.pdf
Clearly, life support is critical for human missions to Mars, and recycling and possibly use of indigenous Mars water resources are necessary elements of any rational plan to make such missions feasible and affordable.https://phys.org/pdf79015566.pdf
Mars journey: Unsolved technical problemshttps://www.nasa.gov/content/life-support-systems
https://www.nasa.gov/sites/default/file … cture3.png
#987 Re: Exploration to Settlement Creation » Settlement design » 2021-04-23 16:52:45
Space X do need NASA's support especially for coms and mapping, that's true.
Louis-
I'm looking at things from a different perspective than you. There needs to be political support in order to get NASA's fingers dirty too, and they can generally justify their support of a scientifically based mission. Musk has the colonization covered.
#988 Re: Exploration to Settlement Creation » Settlement design » 2021-04-23 15:17:42
I think we can agree at least that the water ice mining operation will be based on a lot of scientific work and will also yield lots of interesting material samples or involve events of scientific interest.
You have entirely missed my point. There are real construction specialist who are extremely good at what they do, and a team of 6 will make incredible progress in a short time. The geology/exploration team will also be doing some very valuable science in addition to finding reserves of ice and water. They will also be available for some construction work, since they will be responsible for any cave discoveries and evaluation of building sites.
Real construction professionals don't like having amateur help. The old joke about rates they charge: $50 per hour for doing the work; $75 per hour if you watch and comment; $300 per hour is when you help.
#989 Re: Exploration to Settlement Creation » Settlement design » 2021-04-23 15:14:02
The search for water will involve a lot of geological understanding and I am sure will produce plenty of material for scientists back on Earth to ponder. I am not against the pioneers returning with samples from the water ice mine operation.
The aim of the Apollo landing was not explicitly to export human civilisation to the Moon. It was really a combination of a political demonstration and science. The Space X mission to Mars is explicitly about exporting human civilisation to Mars, so I think that is the overarching priority. The rest will follow naturally. I have always said more science will be done in four years on Mars through two Starship missions than was accomplished by NASA in 40 years. That's the context really - Space X don't need to make an major effort to exceed what NASA have done. Once the base is established Universities, Space Agencies and many other bodies will be keen to undertake scientific work on Mars.
For Louis re several recent posts ....
I decided to think about the position you've taken for a while, before attempting a comment .... I can (sort of) understand your position, but on the ** other ** hand, I am reminded of the first expedition to the Moon. While engineering demonstration was the primary objective of that mission, the need for science was considered important enough so that a number of science related activities were included.
Beyond that, I think that the search for water could be understood as a scientific activity, as distinct from engineering, which is about doing something with water once you find it.
Since this is Noah's topic, I am looking forward to seeing his observations.
We (existing (and mostly older)) forum members have an opportunity to help Noah make crucial decisions as he continues and ultimately (hopefully) completes his academic preparation for a career in the Age of SpaceX.
I am hoping that Noah can (somehow) find his way through this period of time so that he is positioned at graduation to either enlist with some existing activity that might be headed in the direction he wants to go, or (outside chance) embark upon something risky such as starting a new activity.(th)
#990 Home improvements » Danish Green Energy Solution » 2021-04-23 15:02:10
- louis
- Replies: 3
Looks like Denmark is thinking big.
They plan to develop a $34 billion green energy island to further develop their wind energy sector. It seems the island will be used for electrolysis of water to produce hydrogen and also ammonia fuels.
https://www.theguardian.com/environment … rgy-island
https://www.youtube.com/watch?v=2GC3VcB0gLY
Ultimately they think they could power 12 million homes - so far more than Denmark's population, and part of a strategy to export green energy to its neighbours.
Denmark is very lucky in its wind energy resources, so this would not be a solution for every country but it is an interesting development.
#991 Re: Exploration to Settlement Creation » Settlement design » 2021-04-23 13:46:12
I think this is a bit of an either-or for Mission One alone because on Mission One you are doing several things never before attempted: setting up an energy system that can generate something like 1MW or thereabouts, identifying concentrated sources of water ice, mining the water ice, transporting it back to base, getting a propellant production facility up and running that will manufacture over 1000 tons of propellant, making the propellant, safely refuelling a return Starship and preparing a Starship for return to Earth. That's a demanding and challenging list of things that must be done on Mission One.
Louis, et. al;
This is another one of the reasons for sending a larger crew. There doesn't have to be any "either-or" choice made. The scientists are there to DO SCIENCE! That's why I included 2 triads of construction oriented crew members. The medical personnel are there to make sure everyone is capable of doing his/her assigned tasks. Yes, there will be a lot of cross training, but there's a lot of knowledge involved in repairing an electric front loader that a molecular biologist wouldn't.
#992 Re: Exploration to Settlement Creation » Settlement design » 2021-04-23 12:47:00
It's certainly a key benefit of establish a human colony but first you have to set up a secure base. Why lose focus by prioritising scientific exploration. I just feel it's not a priority for Mission One - Mission 2 onwards, yes (not least because it will be an important way of attracting investment from universities and other agencies).
Louis-
I disagree. The science is one of the primary reasons for going there--the search for life past and present is of major importance.
#993 Re: Exploration to Settlement Creation » Settlement design » 2021-04-23 07:09:22
Personally I think the last one on your list should be deleted for Mission One, or at least be considered supplementary to successful completion of other tasks.
I think there is an argument for some early experimentation with industrial and farming processes.
Preparation of Starship for return flight (maintenance, testing, loading, refuelling etc) is deserving of its own category as I imagine it could possibly take up something like 10-20% of the pioneers' work time on Mars, concentrated towards the end of the mission no doubt.
Workload
I have summarized the main tasks, did I miss a task?
Main tasks:
-Maintenance (lss, cleaning, repairs).
-Building the settlement (if necessary)
-Production of fuel
-Exploration (search for water & resources)
-Collection and treatment of water
-Energy system "installation"
-Science (search for past or present life).
#994 Re: Home improvements » Vertical Wind Turbine - better than you might think » 2021-04-22 18:44:17
I seem to recall a figure of the wind force for any given speed being, on Mars, 1/20th of that on Earth and it's wind force, not speed per se that drives turbines.
https://sciencing.com/average-wind-speed-mars-3805.html
Viking sites, the average wind speed registered at 2 to 7 meters per second (5 to 16 mph) during the Martian summer. During the fall, the average wind speed increased to 5 to 10 meters per second (11 to 22 mph). Across the year, the wind speed on Mars averaged 10 meters per second (or 22 mph).
wind speed on Mars can reach up to 17 to 30 meters per second. The maximum speed of 30 meters per second (60 mph) was observed during a dust storm at the Viking site.
https://www.grc.nasa.gov/WWW/K-12/WindT … rmula.html
https://hummingbird.arc.nasa.gov/Public … copter.pdfhttps://www.sciencedirect.com/science/a … 4216301724
https://byjus.com/wind-energy-formula/
https://www.rpc.com.au/pdf/wind4.pdf
https://science.howstuffworks.com/envir … urbine.htm
https://resize.hswstatic.com/w_290/gif/ … bine-1.jpg
#995 Re: Exploration to Settlement Creation » Settlement design » 2021-04-22 16:06:52
Musk likes silly and scandalous names...
If it was me I would call it New Earth to get the message across.
Louis,
It speaks to the character of the mission and the crew, for having the audacity to make the first attempt to live on another world, so very far from home, and the alacrity required to make it happen- to willingly accept and meet any challenge presented.
#996 Re: Human missions » Moxie and only Moxie » 2021-04-22 16:00:52
I think they basically have what you desire but NASA seem to move at a snail's pace with no sense of urgency (not suprising perhaps since there is no prospect of NASA themselves landing anyone on Mars in the next 20 years).
https://www.nasa.gov/centers/johnson/en … index.html
SpaceNut,
Basically, they need to figure out how to land a full scale ISRU experiment as part of an actual "How Do We Survive Here?" package instead of merely satisfying intellectual curiosity. The problem is not, how do I almost provide enough O2 for a small dog to survive for a few minutes, it's "How do I continuously provide enough O2 for an entire crew of 6 to 12 people to survive by replacing all losses with a chemically clean output product, and how do I manufacture all of the required LOX oxidizer in time to return the crew to Earth 2 years after they arrive?" The lab scale experiments are the domain of labs. The engineering scale experiments are the domain of aerospace engineers who should only be interested in solving the problem with minimum weight / power / time / money. They already proved that the prototype operated in a simulated Mars atmosphere here on Earth, so the next logical step was developing a fully engineered prototype, so that that could be sent to Mars. Without being able to physically inspect the unit after operating it, I fail to see how much this could actually tell them about the ultimate feasibility of a full scale device, nor even how well the device works in a field environment.
Can this experiment measure how much dust contamination is present in the LOX?
Can this experiment measure how much dust contamination will clog up the intake and air filter or vacuum pumps?
Do you have a method of cleaning the air filter by back-flushing CO2 through the intake, piping, and pumps?
Can this experiment evaluate how much damage, if any, was done to the fuel cell by dust contamination not captured by the intake filter?
All of that is rather of important if you're going to run the LOX through a rocket engine, even one that only has to survive a few minutes of flight. If you can't answer all of those questions using the data from the field experiment, then the data can't inform any decisions about the requirements for a full scale device that has to process many tons of Martian atmosphere over the course of two years.
They have a gigantic vacuum chamber here on Earth where they can pump in simulated Mars atmosphere, with all known chemical constituents, complete with fine iron oxide and volcanic ash "dust", to see how well their complete full-scale system functions under realistic test conditions, as it would be required to do for an actual crewed mission, which should first be focused on merely keeping humans alive and returning them home, as any scientific curiosities satisfied after that point are merely a bonus. After you manage to do that, then you have to figure out how to put that machine on the surface of Mars and have it run in a more or less automated fashion, because that is what truly requires testing.
#997 Re: Exploration to Settlement Creation » Settlement design » 2021-04-22 07:14:08
Steely Dan?
I just thought of a good name for the first crewed Starship that lands on Mars. That first ship shall be christened Audacity. Her sister ship that carries the other four astronauts shall be christened Alacrity. The first true colonization class ship, a ship of the line, a vessel that Starship clearly isn't, shall be christened Enterprise, for that is what she truly represents.
#998 Re: Human missions » Starship is Go... » 2021-04-21 14:53:25
Looks like SN15 is scheduled to launch 23 April at 13:00 local time.
Anyone able to confirm that?
#999 Re: Exploration to Settlement Creation » Settlement design » 2021-04-20 17:25:42
Well as I posted above I see this really as a Phase 2 of urban development on Mars. Personally I would favour terraced hillside boring for residential habs, and not too far into the hill, so we remain connected to the daily cycle of light. But true tunnelling may be fine for applications like rover garaging and maintenance, (artifical light) farm habs and warehousing.
Thanks GW. Considerations like this certainly limit design options.
The more I weigh the pros and cons, the more sensible it begins to look building most things underground on Mars. On Earth, an underground house has 20-30% higher capital cost, though negligible heating costs. But on Mars, everything built on the surface requires the use of space suits and pressurised vehicles until it is pressure tight. The buildings and equipment must tolerate low temperatures and high temperature ranges. Structures like domes, would not protect their inhabitants from cosmic radiation. Whilst this won't be imminently catastrophic to human health, it is a hazard that should be avoided. Surface structures must be insulated and heated. A dome would lose a lot of heat over the course of a Martian night.
I think that Elon Musk probably realises this and this explains his interest in shipping boring machines. There are some things that cannot easily be done underground, like growing food. We still need sunlight for that, unless electric power is very cheap. So heated greenhouses are going to be a necessity. For most other infrastructure, it makes more sense going underground. One additional advantage to going underground, is that most structural elements can be designed with compressive forces in mind.
#1000 Re: Home improvements » Vertical Wind Turbine - better than you might think » 2021-04-20 17:08:37
Why don't you read up on compressible fluid dynamics?
Alternatively I could pull out my teeth with pliers! lol That's why we have engineers - so people like me (the sort of philosophically minded person who asks why in a physics undergraduate primer they reference "force" about 10,000 times without ever actually defining what it means!) don't have to. 
But yes, I was thinking with higher wind force during dust storms this might be a useful addition to energy generation. The only reason I would think it worthwhile really is that the devices seem simple and cheap to make and to install. They could probably be made robotically in the thousands with far less effort that would go into manufacture of either PV panels or a nuclear reactor.
louis wrote:I was wondering whether we could maximise wind force on Mars by creating tapered tunnels or gorges, so wind force is concentrated at the end of the narrowing tunnel or canyon - with the wind turbines sited at the narrow end. Would that work?
Yes. If you find a canyon with the right orientation to funnel the westerly winds. But a better question would be, will it increase wind speed enough to overcome the limitations imposed by very low atmospheric density? Why don't you read up on compressible fluid dynamics and work out what sort of velocity increase is likely to occur? You can then use the equation I gave you earlier to work out power per unit of swept area and compare it to typical values on Earth.
I think you will probably find that very high wind speeds are needed for this to produce comparable energy per unit swept area. It might work in the sort of speeds prevalent in dust storms.