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Did not see the content so am unable to render any other option than to take JoshNH4H word on it.
GW's post of watch the seasons did play true up until this last couple of weeks when we go the monster nor'easter cycle as the lawn was devoid of snow....normally that never happens until late april or may...
I have always enjoyed the technical content of JoshNH4H posts, but from things that he has said in the past I don't think he is a reliable moderator. He has strong personal biases that influence his work. I have biases of my own, but I never stoop to censoring other people.
But it makes little difference either way. I have run out of spare time for this board and do not have the resources to make a detailed contribution anymore. So I think it is the right time to leave.
I will leave on this parting note: I have serious doubts that we will ever get to Mars. The reason being that I believe that the global economy is now hitting serious limits to its resources, especially energy sources. These limits have been evident in the poor economic growth of western economies since the 1970s, the almost complete absence of growth over the past ten years, plummeting interest rates since 1980 and exploding inequality between the rich and wage earners. Globalisation was, more than anything else, an attempt to shift manufacturing from areas where resources had grown scarce, to areas where they were still abundant. China built its manufacturing industries on a base of cheap labour and cheap coal energy, which is now entering decline. Globally, debt is some 6 times greater than annual GDP. Over the next ten years, the global economy will suffer a significant contraction. Various excuses will be given by central bankers, but the underlying cause will be a decline in the volume and quality of fossil fuel sources that fuel all economic activity.
https://medium.com/insurge-intelligence … 7344fab6be
If space enthusiasts are to fulfil their goal of colonisation of other planets and space itself, they must begin by solving this problem.
Good bye. It has been pleasant working with you all!
Antius: Watch it with the antisemitism. I will delete posts or discuss a ban if I have to.
Do what you want. I have other places to be. And this board becomes even more pointless than it already is if our posts get deleted.
Voltaire: "To learn who rules over you, simply find out who you are not allowed to criticise"
Aluminium alloys have been used in cryogenic applications. They work, but have problems. Some problems with aluminium are it's generally poor fatigue life, it's high energy cost and high coefficient of thermal expansion.
Low temperature embrittlement will be a huge problem for any above ground pressurised structure on Mars and greenhouses need to be above ground. I suspect that any serious settlement on Mars will need to get cosy with the idea of nuclear heating. Every square metre of greenhouse will need 300W of heat energy to keep it above freezing at night. We are trying to colonize a planet that is as cold as Antarctica. On Earth, we would burn fossil fuels to keep non-pressurised structures warm and ship in food from elsewhere. On Mars, there are no fossil fuels. Food must be grown onsite in pressurised structures. That means nuclear heat, lots of nuclear heat. Each human being will need a continuous supply of about 30kW of nuclear heat just to supply him with food.
I am not sure I understand exactly what you are proposing. Do you mean a concave metal frame with a berm counterweight?
Trump is irrelevant. Warming is real. You can see it if you are aware of when spring actually comes, and when fall actually comes. You do NOT need to know whether mankind had anything to do with causing it, to know what to do to try to head it off or at least delay its effects. That is just basic physics of energy conservation, of the radiation of energy, and of the energy transmissibilities of various gases as measured in the lab very repeatably.
GW
Fossil fuel depletion is real. It will kill you long before global warming does. Without fossil fuels, you don't eat. That situation may be closer than you think.
[This post has been moderated to remove antisemitic content]
Here is one fact that Trump clearly does understand. All of the affluence that we human beings enjoy - warm homes; abundant material goods; high technology; scale economies; cheap and rapid transport - all depend on the abundant stored energy in fossil fuels. Without them, modern affluent lifestyles would be unsustainable and at least 80% of the Earth's population would swiftly die from the cold and from lack of food. As things stand, there are no alternative energy sources available that can be scaled up to replace the abundant but finite source of energy provided by coal, oil and natural gas. Since economic prosperity is a linear function of energy supply, restricting that energy supply would harm American prosperity. Trump knows that and is instinctively opposed to political ideals that would compromise what he understands to be the source of all human prosperity, even if he isn't wonderfully articulate in his reasoning. The threat of climate change is a problem that will hit the world of tomorrow. Today, any measures that restrict access to fossil fuel energy, restrict human prosperity in equal measure. Trump is right for the wrong reasons.
Fossil fuel depletion is a much more pressing issue for most of this planet's population than climate change. And it is a severe problem right now. It was the principle cause of the 2008 Great Recession. It is the reason that western world economic growth has been weak since the 1970s; why wage rates have not risen in almost as long; why interest rates have had to drop constantly since 1980 and why a Great Depression worse than the 1930s is just around the corner. Unless circumstances change significantly, the next few decades will be a period of tumbling life expectancy and diminished living standards for most of humanity. The last thing we need is silly rules that prevent us from exploiting what resources do remain.
Nuclear energy is the one thing that might forestall the approaching dieoff that will otherwise ensue as we hit the fossil fuel net energy cliff. This is conspicuous in its absence from Trumps energy policy. That is deeply unfortunate, because even a complete relaxation of environmental protection cannot extend fossil fuel production for more than a little while longer. When it stops, we stop eating. Our situation is as brutally simple as that.
The distance between Greenland and Iceland is only a few hundred kilometres, I think. That would keep the tunnel with the EEZs of Iceland and Denmark.
Alternatively, people could fly that distance, or take a ferry. Take the train from Manchester to Iceland, fly/ over to Greenland, and take the train to Boston via Canada. Not as simple as a single journey, but perhaps worth it if liquid fuels become a lot more expensive. It probably makes more sense for cargo than passengers. Would an electric ship manage that distance?
Maybe. Ships are in many ways much easier to adapt to non-fossil fuel energy sources than aircraft, because they are nowhere near so limited in terms of power to weight. If they work on stored energy, the mass of the energy store can be part of the ballast weight of the ship, provided it is within or close to the keel.
A ship could be nuclear powered with a pressurised water reactor. This has been done before and it would be easy in principle to adapt commercial PWRs to provide propulsion. Or it could be powered by batteries or maybe even stored thermal energy in a molten salt with an S-CO2 generation cycle. Cryogenic energy storage is another possibility, as the ship is surrounded by a huge heat sink. Ships could even burn coal, liquefy the CO2 and dump it in the deep ocean with a long pipe. Far more options using ships. Provided people are willing to slow down a bit. It would take a ship about 4 days to get from the British Isles to New York. The journey could be a lot more comfortable than the cramped standard class seats on a transatlantic jet. But there is no way it could possibly be so fast.
I would happily accept a 2 day trip across the Atlantic, if I could travel in style and it was cheaper than a plane. Airship or transatlantic train, though I'd prefer the former given the views (no use having a window when you're in an undersea tunnel). Passengers who have to get there quickly can take the far more expensive jets.
Problem with airships is that although they could ultimately be more fuel efficient than jets, they are limited to speed of 60-100mph. That is economically difficult because the vehicle delivers fewer passenger-miles within the investment window. That would make an airship transatlantic flight expensive. For shorter journeys of up to 1000miles, they may compete better with jets and land transport. Energy efficiency is a function of size for an airship, so bigger is better.
As mass transport, i.e. more than just a technological curiosity, there is really no alternative to hydrogen as a lifting gas. Bringing back the airship would require that we mitigate any hazards involved in the use of hydrogen lifting gas to at least tolerable levels. That would be easier today than it was in the 1930s, but it may not be possible to reduce risks to levels that satisfy aviation authorities.
Short haul flights are classed in Europe as distances shorter than 1500km. With modest improvements in battery technology and innovative airframes, the electric aircraft might stretch to the upper limit of that without sacrificing payload.
https://en.m.wikipedia.org/wiki/Flight_length
London-Berlin = 931.5km
Edinburgh-Dublin = 350km
London-Madrid = 1263km
London-Barcelona = 1139km
So this could take care of most air travel within Europe.
Achievable with 1 stop:
Paris-Moscow = 2486km (stop at Warsaw).
Glasgow-Helsinki = 1768km (stop at Stockholm).
Transatlantic is much more difficult. As Terraformer says, you would need to hop from Scotland to Iceland, from Iceland to Greenland and from there to Canada. You probably wouldn't use an electric plane for transatlantic flights as all those stops would be logistically expensive and it is better to fly in a straight line.
How much lithium are you going to need for that? How much will that cost, since you're competing against other uses such as grid storage for it?
If you want to electrify travel over a few hundred kilometres, use trains.
The 747-400 carries 216,840L (170 tonnes) of fuel. So a battery mass about the same, although it delivers a shorter range. That is 315 times the Tesla battery mass. About the same battery mass per passenger as the Tesla.
The electric aircraft is a much more efficient use of lithium, because a given battery mass will deliver far more passenger miles in its lifetime – likely 20 (or more) times greater. This is because: (1) Trips are longer – a car will typically make lots of trips <40km in its life and relatively few trips greater than 100km (incidentally, this is why hybrid vehicles make more sense than pure electric); (2) It is faster – my calcs are based on a Mach 0.8 cruising speed – the same as a 747.
That being said, I agree that trains are probably a more energy efficient means of transport per passenger km. But they aren't much good over water and they are slower.
The electric aeroplane could benefit from some significant efficiency advantages over the kerosene propelled counterpart. Firstly, the engines do not need to consume air to generate power. They can be tucked away inside the wing with no inlets. That is a huge reduction in drag and it opens up greater freedom in airframe design. Secondly, a turbojet needs to rotate at high speed to achieve necessary compression ratio. This results in relatively poor propulsive efficiency because even high-bypass turbofans tend to rotate too fast and produce exhaust velocity too high. Gear boxes are heavy and introduce failure modes. An electric motor speed can be tailored to the airspeed of the plane achieving much greater propulsive efficiency. So range could increase substantially above what I have calculated.
Ultimately, what at first appears to be a crazy idea could make a lot of sense.
The range of a 747-400 is given as 13,450km on wiki.
The energy density of kerosene is ~43MJ/kg and turbojet efficiency is ~30%.
The energy density of lithium-ion batteries is 0.36-0.875MJ/kg – say 0.9MJ/kg for a scaled up, near term battery. DC motor efficiency is ~80%.
Crunching the numbers gives a range of 750km for a 747-400 airframe propelled by electric motors. However, a kerosene fuelled plane gets lighter as it consumes fuel. So maybe 700km is a more realistic estimate. With a 20% margin that puts maximum range at 500km.
That could have uses for internal flights. Especially if aircraft can function like buses, landing at an airport, dropping some people off and picking others up. On the ground, they could swap batteries. More streamlined airframes may push up the range of electric planes. Maybe one day a 1000km range is possible?
The economics of the prospect are marginal at present, but may improve as oil depletion accelerates. A kg of kerosene costs $0.5, which works out at 1.163c/MJ or 3.88c/MJ of engine power. One kWh of grid electric power presently costs about $0.1 in most countries, or 2.78c/MJ. One MJ of engine power therefore costs 3.74c.
The operational constraints and additional infrastructure imposed by an electric aircraft would appear to make it marginal at present. However, if fuel becomes more expensive and/or electricity becomes cheaper, the balance may shift in its favour. Most likely, both fuel and electricity will get more expensive, as fossil fuel depletion continues and we fail to find alternatives that deliver at the same cost.
Ok. Interesting ideas.
Not sure how gym equipment can simulate micro g. A better bet might be a bungee rope. Maybe skydiving - you get 5 minutes of zero g before leaving a lasting impression on the Earth.
Electrically powered propulsion always comes off poorly from a power (thrust) - weight perspective and thus always has poor acceleration. The power conversion and generating equipment is heavy and to get a passable Carnot efficiency, the a power cycle must operate at very high temperature (challenging for materials) or dump heat at low temperature (huge radiator mass). Energy transitions are very expensive in terms of mass. Project Neptune in the 1980s was a US attempt to push nuclear-electric propulsion to its limits by developing a boiling potassium reactor with an MHD generation cycle. Whether a boiling potassium reactor is something you want to trust to the likes of Malcolm Reynolds and Kaylee Fry, even in the emptiness of interplanetary space, is questionable.
The best option in terms of power-weight is always to generate huge amounts of heat within the fuel and use the products as reaction mass without any heat transfer. Heat transfer and energy transitions are rate limited and imply a lot of extra mass. Hence, the enormous power to weight ratio of chemical rockets and the huge thrust-weight and ISP of the nuclear salt rocket - which is basically a torch ship. High ISP x High thrust = Very High Power. The solar rocket and nuclear thermal rockets are the next compromise in terms of thrust to weight and ISP, because energy transitions are kept to a minimum, heat stays as heat and the equipment involved is light-weight in comparison with the energy flux it receives.
Railguns might be useful as fixed, but steerable, installations on a large body for launching mined products in vehicles that will withstand the massive accelerations. These vehicles have to be able to make orbital corrections so that they can reach their destinations, and if there is no atmosphere at the destination, they have to be able to brake by reverse thrust. Still you would have nearly halved the propellant mass to be launched along with the vehicle and the product. This removes the objections due to the size and mass of energy plant required.
Rail guns or coil guns for launching lunar materials are only desirable if the payloads are strictly dumb (i.e. ore packages). Building technology into the payloads such that they can make course corrections undermines the point. The mass driver (coil gun) was supposed to be a means of very cheaply launching large quantities of raw material payloads, that could be collected in a large bag, transported to an ore refinery and processed into metals to support space manufacturing. If the payloads need to make course correction then that idea doesn't really work.
Some interesting concepts here. Tracked vehicles are less likely to get stuck in soft terrain than wheeled vehicles. But they are heavier and less energy efficient.
I wonder if a hybrid electric vehicle could be a good option for Mars. A short range 40km battery, which can be charged with roll-out solar panels. An IC engine mounted to a generator for when greater speed and power are needed or when traveling close to the poles. Wheels could be some kind of fibre reinforced polymer.
Either way I should leave and never return. Bye then, hope we never meet again.
Void, man, you sound depressed. Dr Antius prescribes prozac. It takes a while to work, but after a few weeks it kicks in. It works a treat, trouble is it does make you lethargic.
In answer to your question, you are frequenting a board dedicated to colonizing another planet. Rational is relative. Good ideas voiced here may get used someday, but will bring no personal profit or recognition to any of us. Sober up and get laid or take Prozac. If you enjoy this board, then come back. If you don't, then don't spend another minute here. Enjoy your life and never look back.
Trump makes everyone proud to be Merican!
All hail the most intelligent and wonderful leader!
Trump simply doesn't have the level of education to be a great leader. That is truly unfortunate, because a great, patriarchal, racialistic strongman, is exactly what the western world needs right now. Someone that can rip the parasitic Jewish deepstate out of US politics, much as one removes poison from a wound. But he just doesn't have the intellect, or the youth, or the dynamism, to be the 'Putin of the West'. That is probably one of the greatest tragedies of this century.
That being said, I can't help but love the man for the enemies he has created, even if I do cringe at some of the decisions he makes. He is in his own way a great man and he is a serious setback for deepstate agenda. The corruption and manipulation that was (and is) employed against him, has exposed the US political system and media for what it is - a Zionist oligarchy bent towards ends that have nothing to do with the best interests of the American people. The fear and outrage they display at having this 'gentile outsider' invade their camp, has been the greatest show on Earth. Trumps greatest achievement up to now is keeping Hillary Rodham Clinton out of power. She is without a doubt, one of the most corrupt and thoroughly vile people ever to hold public office. Many US voters supported Trump simply to keep her out of power. Apparently, the idea of another 4-8 years under the Clinton Crime Family (TM) didn't appeal to them. I can't imagine why.
https://www.nbcnews.com/think/opinion/p … ncna849681
"Marcie Bianco The patriarchal race to colonize Mars is just another example of male entitlement
The presumed right to use and abuse something and then walk away to conquer something new is a hallmark of colonialism."Popping back in to New Mars (after an absence) to assure others here that not all women (myself included) share this viewpoint.
Palomar7, This Marcie Bianco sounds like what we British call a Champagne Socialist. She is clearly well fed, well indoctrinated with Marxist nonsense and generally doesn't understand human evolutionary psychology.
Patriarchal male entitlement? The male instinct to gather new resources and expand into new territory stems from our need to feed our families. From an evolutionary viewpoint, men that didn't do this watched their children die. When women are put in a position of authority, they tend to do these things as well (think Margaret Thatcher).
Women instinctively choose men that can 'provide' for the very same reasons. Men instinctively display traits that allow them to attract and secure a mate - I.e having lots of cash and building a really big nest for a woman to lay her eggs in. Patriarchal male entitlement is a poor description of what this is; a more accurate description would be human evolutionary group psychology or perhaps, reproductive psychology. It is not specifically male and is not even specifically human. Any species would do the same thing in the same position. It is driven and reinforced by both men and women, to the same basic end. (A family is probably something that this man-hating freak doesn't have. If she does, I feel sorry for them.)
Often this instinct has a darker side to it, i.e. resource wars. Valuable resources are seldom simply there for the taking. They are preowned by another tribe that must be conquered. This is why men tend to be aggressive and warlike. Pushovers don't bring home the bacon. (That's why girls don't like Pushovers. They let the children go hungry.) Women supported this conquest from the sidelines for quite obvious reasons and Crusaders rode off to war with ladies favours in their hats. Men are the visible actors in this whole affair, but women encourage and support them and swoon over them, because they get to benefit from the spoils. Men are not trying to 'grab pussy' as such, they want pussy to come and live in their nest and produce children that carry their genetic legacy. Donald Trump is a fine example of a man who can provide. He builds a billionaire business empire to attract a beautiful bride, houses her in a mansion, produces children with her and then displays nepotism finding them well paid jobs within his administration. He is doing what every good father should do! He is in fact a prime product of evolution.
Feminists that oppose this process are not simply opposing men, but all natural evolution. This makes them more than a little perverse in my opinion. There is something inherently wrong with women that end up hating patriarchal men. The patriarchal men are the ones that stick around and take an active role in raising the family and go and kill the tribe next door to gather more food and bear skins to feed and clothe them. The alternative is a sperm donor, that gets you pregnant and then leaves you to be as 'feminist' as you like. Women don't traditionally like men like that, for very good reasons.
Expanding onto another planet is a more benevolent expression of the basic human instinct to gather more resources for the benefit of our children and tribe. It is one of the few occasions when we can collectively expand without conflict. Or at least that's the idea. I doubt very much that the various nations of the Earth will peacefully divide up the new lands without shooting crap out of each other.
P.S. To all poorly educated Marxist women that hate 'male entitlement'. Just remember that you made us what we are, through millions of years of sexual selection. Sorry you don't like the fruits of your own ancestors handywork. And if we hadn't behaved this way throughout history, mankind would not exist. You would not exist to spout this nonsense.
I agree with Terraformer that the energy requirements of Mars residents will be pretty high - certainly higher than 500 Watts per person. Mining, transport, agriculture and life support are going to be significant consumption factors.
You have said pretty much the opposite in past discussions - that the energy requirements of a Martian settlement would be quite modest and we don't need heavy investment in this area. So which is it?
Also, are you really going to have a community of 100,000 dependent on one energy source? If the energy source fails, you have a catastrophe on your hands. Won't you need back up - possibly a doubling of your tonnage immediately.
Not really what I was saying. Maybe we will need a lot more than 500W, that was an example of how to meet a bare minimum. At 500W per person, 1 x 50MWe nuclear power source would meet the requirements of 100,000 people. But in a city of 1 million there would be 10. So there is never really an issue with redundancy. Having more redundancy would mean having more power. If it takes 1 reactor to meet life support and subsistence requirements of a base, then the second is unlikely to sit idle. It would be used to support ore processing, exploration, manufacturing and exploration. In the event of failure, these operations could be scaled back until repairs are made.
The mass driver would only appear to be workable at very low acceleration. At an acceleration of 0.001m/s2, a vehicle will achieve dV of 10km/s in 116 days. Under this scenario, with a 30km/s Vex, your power supply would need to be 2MWe and would weigh 20 tonnes. That's more doable.
Reaction mass would become a serious pollutant if it accumulated in close orbit around Earth, Mars or Lunar. Using a liquid or ice is one way around this. O' Neill discussed the use of liquid oxygen, since huge amounts would have been produced as a biproduct of metal production from Lunar ores. Another option discussed was grinding materials to micron sizes, such that they would not penetrate a spacecraft hull. Or perhaps carefully adjusting exhaust velocity such that reaction mass intercepts the Earth's atmosphere.
P.S. I wonder how small a dust particle needs to be in order for sunlight pressure to accelerate it to say 1km/s over the course of a year? This would ensure that pollution did not accumulate within planetary orbits.
Gerard O'Neill explored the idea of small, private spacecraft in his book 'The High Frontier'. His propulsion solution was the mass driver engine. This is basically a coil gun, which accelerates solid materials to velocities up to 10km/s using magnetic fields. The power supply would have been solar PV.
This is a simple system and can be relatively low tech and easy to build. It can also use raw materials gathered from asteroids as reaction mass without any processing.
The downsides are low acceleration, large physical size and multiple failure points.
Another option would be an arc-jet or VASIMR, using dust as propellant. This would be smaller and more compact.
"NuScale's self-contained 50 MWe integral pressurised water reactor design houses the reactor core, pressuriser and steam generator inside a single containment vessel. A power plant could include up to 12 power modules, each 25 metres in length, 4.6m in diameter and weighing around 450 tonnes. Each module incorporates simple, redundant, diverse, and independent safety features."
If Musk realises his ambitions of a city of a million people on Mars, those people will need to be fed using locally grown food. That means pressurised greenhouses that will need to be heated to keep them above freezing. One hundred megawatts of waste heat would go a long way towards achieving that. If we assume that 100W of waste heat is needed per square metre of greenhouse and 100m2 of greenhouse feeds one person, then a city of a million people would need ten of these reactors to supply the heat needed to produce food. They would also generate 500W of electric power per capita (4400kWh/year) which is about the minimum needed for an affluent lifestyle.
So in conclusion, a single Nuscale 50MW unit will support up to 100,000 people on Mars. If the cost of shipping it to Mars is $100/kg, then transport costs would be $45million, or $450/person. If purchase cost is $2000/kW for a mass produced unit, that's $100million per unit. So total cost of $1450/colonist. Quite affordable.
If we find perchlorate rich brines on Mars and methane gas reservoirs in similar locations, maybe we generate power from both using some sort of stationary PEM fuel cell?
This could be a key technology that makes the inertial confinement fusion direct rocket a reality.
http://www.sciencemag.org/news/2018/01/ … mpty-space
Unfortunately, an Earth Launch FDR would generate huge EM interference problems and would also pump the Earth's ionosphere with charged particles. There ain't no such thing as a free lunch.