AngelLestat

I knew that, but how hard it can be? after all you still use a heat exchanger in which hydrogen go through Maybe is just an issue that can be solve with material selection...

2 stages vehicles using a sable engine will have much higher operational cost, refurbish, things to fail, planning and ensemble cost. Then it will take much more time to launch cargo between launches. Jet engines are more expensive than rocket engines, sable would be even more expensive than jet engines, and the main point of a sable engine is that it works in the atmosphere upto match 5 and then as a rocket. Match 5 is no enough to reduce a lot the cost of a second stage because is still needs most of the deltav to go, but it can give you the benefit of 1 stage to orbit. You can have few benefits with a first stage sable and a second stage rocket. But you will not have an economic advantage over falcon9 or heavy, due extra cost of aerodynamics and sable engines. So if someone should use a sable engine is just for 2 things.. a super fast airplane, or 1 stage to orbit vehicle. Hi blowfish, The one thing that I never understood well is why they use the helium loop instead of just the same hydrogen which would increase the efficiency, because heat exchangers are not 100% efficient. So you use the same h2 as a heat engine cooling the air that enters and the temperature difference will help to run the h2 and lox pump and compressor. Or I am missing something? Also.. at those temperatures in which the incomming air is cooled, is not possible to split the nitrogen from the oxygen to increase the power of the combustion?

Maybe spacex does not want to show the landing in live in case other space company learn from their mistakes, so they may need to see the video and edit in case is something of value to see. Or.. is just the vibrations, or any interference to the communications from the engine plume. In the video it seems as the stage landed very on the side of the barge.. no enough to support the four legs.

No, he doesn´t. I know very well of what I am talking about. But this is not the place.. I made some comments in this topic: Nobody said that it will be easy, but a 2STO with sable engines does not have much sense, because it will have a huge cost also without the real benefits of 1 stage to orbit in reusability vehicle, mostly for the time it will need to relaunch, which is directly translated to cost. In that case keep the falcon9 or heavy.. there is no difference. Ok, my english was no right in that sentence... what I wanna said is that ESA did an study about if skylon has economic sense taking into account all costs and the future demand.. That economic study took 1 year to complete with a cost of 1 millon euros (the economic study). The cost is just to point it was a serious study.

I was many times in this discussion like many others here so I will be brief.. The demand and economic argument: some believe that there is no enough. I believe that space demand will rise by a lot, and it is already rising even at current costs, ESA make an economic study (1 millon euros cost 1 year to complete) about skylon and they found that it has economic sense. Of course that the development cost is very high, the same as any airplane.. due mostly to aerodynamics. But no so high as many might think, the main goal at first is just transport cargo, a normal airplane needs to make an airplane that will work the 100% of the time 24hs 365 days all years with 400 innocent passenger who paid its ticket. Yeah, skylon has many other difficulties to overcome, but all are completely in the range of our current technology. Of course he criticize skylon... if investor think that in less than 10 years spacex may have problems competing with skylon, they may choose not to invest today in spacex. (I am not saying that it would) He also said that fuel cell vehicles does not have sense.. but they have even more sense (in the transport business) than normal battery vehicles. He needs to show that their products are the best with no question to make the best sales and attract investors. USAF review only the engine... so said that their are no interested in skylon is just your assumption. They said that it will be nice to start with a 2 stages vehicles at first.. but I dont remember nothing about a skylon comment...

maybe a 6u cubesat mission could be funded using that site only if the promoter of this adventure is a very famous person.

Yeah.. apparently telecommunications tech also not changed, they keep using the electromagnetic spectrum. You don't make the best electric car in the industry just doing what others try before, the same goes for spacex. I accept that Elon business models are way superior than other companies, but that is not the whole secret for their success. For example, they needed a light way to convert DC current in AC (because AC motors are way superior), if they would use normal inverters to turn 250 kw DC to AC it would need a huge and heavy inverter, but they solve that placing the inversion task in the motor itself by breaking the rotation into many phases and assigning each phase to a different subset of the battery pack which made everything cheaper, small and light, this is also failure proof against batteries issues. The battery was arrange and design to be cool it self. And mostly all main components of the tesla S are one step ahead from the rest of the industry. If all the things that Spacex make are not innovative, then in that case NASA did not accomplish absolutely nothing in 40 years with a lot of extra money and time. I am very aware of all the research and new technology + knowledge in which NASA was involved and currently keeps working. Like inflatable heat shields, rotor capsule, aerodynamics, theoretical atmosphere models, biology, physics, etc. Many of those things was accomplished over the apollo or voyager ages. But I would love if they could be more cost-efficient and focus in their real task.

Answering again the OP question, they would be able to do a lot of things with that money, but they will become a bit more inefficient than today. But well, all solar system is open after that, submarine to enceladus or europa, venus-mars manned mission, asteroids, balloons to titan and jupiter, etc. Then new type of airplanes and different techs. If what Elon does is not new tech, then nothing it is. Tesla: a big part of the whole car is new tech from their own hundreds of patents, from transmissions to inverters, special fuses or even an AI auto drive software that is continually learning. Then you have hyperloop in development.. crossfeed for falcon heavy, a new special escape system for dragon v2, new methane engines, etc. But maybe you are refering to really revolutionary tech that will change human history as the laser or the transistor.. Well in that case reusable rockets should enter in that revolutionary tech.. because before they achieve the first steps, many on the industry said that was impossible.. There you have all the new tech to make that possible as fins, legs, software (that also counts as new tech of course), special structure levels and engines able to throttle. All those developments with almost no money in comparison with nasa developments. What you call modern nasa? Because I dont see nothing of efficiency in modern nasa. You will have more bureaucracy that is true.. but not so much. After all, part of the spacex´s money comes from taxpayers.. or not? If you said that nasa spent so much money due "efficiency control" of nasa budget and achievements, then the whole arguments fall.

I am not sure what NASA could do, but I am sure that if that money is given to Elon Musk instead NASA, he will accomplish 5 to 10 times more. So NASA would do 36 times the things they do, and elon musk would do around to 250 times the amount of things that NASA does now. This mean, launch an proxima centauri probe in 40 years with many of other interplanetary missions.

I am not saying that covering the stage with a blanket worth it, because in theory should not be many situations when this will be useful (delays). But not sure how the action of remove a blanket can add "a huge amount of complexity" as fredinno said. In fact I imagine that the whole operation can be executed just pulling from a rope.

?? what you want to show me? the amount of radiation on mars surface? I already know that.. an average is mentioned in this table that I did yesterday: If you are mention the curiosity RTG power source.. that only generates 2kw thermal, the most common nuclear reactor on earth generates 3 gw thermal (1 million times more). Now mars surface is 3,5 times lower than earth surface, its atmosphere is 204 times less massive, you can only count the dust mass that travels over the surface, because you dont have rain or plants to carry that radiation under the soil or to diluted.. earth also has an amount of water that might cover all earth surface with 1500m of depth. That is a lot of mass compared to mars to dilute and reduce radiation issues. So I can not tell you with accuracy how many times worst is a nuclear accident in mars, but it will be very considerable even at the radiation levels that already has. If the same dust is the source of that radiation, then it can be in the material you use to made products, or habitats, it can enter to your habitat or your lungs. A radiation source stick to your skin, it becomes a real problem. Someone may need that (low deltav movility) only if you have a venus popullation and a mars popullation, what is the point to have a lot of population on orbit? Where they would go? You dont even need them there, because you said that you mine the asteroids with specialized machinery on the asteroid location... I understand that might be a niche for certain amount of people that might be convenient to live in LEO or moon orbit. But if you want to sell products to earth popullation, it will cost you an extra to sent those down there.. you can sale products to those who wanna produce space applications.. is not a small case, but is not so bigger neither.

Are you kidding me? that is exactly what you did with your previous message.. You said that the fukushima accident was all bluff... I disagree and you now said that I am trying to derail this topic? I don't need to have that discussion again.. if you want to hear my opinion on the topic I invite you to use the search tool with related keywords. But does not matter all the things that we can said.. you know that I am right.. you can not put a reactor in mars without worrying on the risks, and nobody will allow to a company or country to experiment with the planet unless all are agree and there is no pollution risk.

Yeah, the book is called the dragon fly or something like that.. from robert forward, they travel to epsilon eridani. But that laser-lens 3 stage mechanic might be more practical for interplanetary transport, but even at these distances it will be an engineering nightmare on optics and scale.

I made some tables that might help in this discussion, I hope you also help to correct or fill. I post them here: You can live.. is the whole point of colonization, I explain that you dont need to live of trade, you can have a successful economy and growth with zero trade. Space colonies will be very expensive, the difference in deltav to reach venus vs low orbit is very low, then once you have the same level of development in venus or mars than earth.. it will have more potential to growth than a ship which just mine asteroids. If you move to the asteroid belt, your energy cost will rise a lot, and you are very far from earth to sent those minerals back. Why people will live up there? I imagine that you have your asteroid in LEO, you can control all from earth. Of course at begining it will be cheap to mine some asteroids, like heavy metals or just ice for fuel. But I dont find any reason to have a big population living in a ship which purpose is just move "that big fat habitat mass" to an asteroid which is further from the sun (less energy), and what if that asteroid just has ice or heavy metals.. then you need at least 2 or 3 asteroids (at the same time) to supply that big habitat? but you need to produce products too, so you need to move all the extra industrial ships with you. Depending the time.. in one age cave hopping cavemen where the only ones who survive.. with our technology, planets seems a better target.. and if our tech increase.. then why deltav will be an issue?? How much "fuel" would spent a fusion ship like the avatar's valkyrie? Ask that to the 200000 people who had to abandon their home in japan, to the 200 billions spent in reactor decommissions (which put to japan for far in the number 1 country with more debt from the world) Even if the radiation levels on some locations might not be so high in comparison with the max limit of nuclear workers.. it means anything? no.. because nobody really know for certain the radiation issues in many of your life aspects like having children and the implications on their dna)... who will bought you the food that was made in a radioactive polluted area? Also.. you think it will be ok for some company or country just pollute the whole planet because they did not spent in extra care? Venus on the other hand does no need nuclear.. they have gradient wind.. something much much better with no need for storage and with high powers densities.

Well, I was spending some free time gathering and filling data related to potential colonization sites the best I could, for sure there must be big errors there that I will request your help to improve the numbers with better estimations.. because there is no official data for many of those. But looking info with this format is the only way to compare and understand the real difference between the locations. Possible colonization sites - data Vs Earth: Gravity Pressure Temp (co) Thermal Con Solar Power Radiation Launch W dV LEO to dV back E.C. Com. Delay Mercury 0,38 0 -173 to 425 0,2 2000 350 90 days 17,2 13,5 4 to 12 min Venus Clouds 0,87 0,7 20 to 60 0,9 600 10 584 days 3,8 10,4 2 to 14 min Earth Cities 1 1 -20 to 45 1 240 1 - - - - Moon 0,16 0 -153 to 123 0,2 300 200 15 days 5,6 2,55 1,3 seg Mars pole 0,38 0,006 -40 to -120 0,35 80 90 780 days 7,3 6,5 3 to 22 min Mars low lat 0,38 0,006 15 to -80 0,3 180 125 780 days 7,3 6,3 2 to 22 min Asteroid Belt 0 0 -120 0,2 180 250 460 days 10 7 18 to 38 min Europa 0,13 0 -160 0,3 20 1000 400 days 13 13 33 to 53 min Enceladus 0,01 0 -200 0,3 6 300 385 days 9 13 66 to 92 min Titan 0,14 1,5 -180 1,4 7 10 385 days 7,3 11 66 to 92 min This second table is not complete, these are all estimations based on data gathered, the first table try to measure all aspects with respect to earth, this is the same but from the cost perspective. Before someone start with critics, it will be more helpful if collaborates with its own perspective on the numbers. Some numbers might seems with over precision taking into account that is only a rough estimation.. you should ask why? I understand that it would be more correct to use bad, regular or good for those cases, but using numbers it help me to estimate other numbers based no others, in other words if I start with an estimation that it should cost 20 times more or less than earth for certain location.. then that value can help me based on general properties and other variables, to estimate values for other planet in base to comparisons. (radiation is base on earth, which it has 2 smv per year, so if in the table you see 300, then it means around of 600 smv per year.) . Cost of: Energy h2o CarbonF Light E. Heavy E. Import from earth Export to earth Habitat Mercury 0,5 70 10 50 0,2 2,7 0,6 Venus Clouds 0,4 50 0,08 0,5 0,1 1,3 1,3 SpaSta LEO 1 * * * * 1 0,1 Moon 1,2 60 30 0,2 3 1,6 0,1 Mars Low Lat 3,2 25 0,3 0,5 4 2 0,4 Mars Poles 1,5 3 0,3 5 5 2 0,4 Asteroid Belt 2,5 10 10 2 0,05 2,3 0,9 Europa 0,9 4 15 7 15 3,5 0,8 Enceladus 0,8 2 20 10 20 3,5 1,2 Titan 0,7 7 1 0,2 5 3 3,5 Some examples of how I get some numbers: Energy is base to solar, wind and nuclear... choosing the best case for each location. Mercury is solar, PV films require extra care to work in space and at high temperatures, it needs extra radiators (no much), mercury is kinda tidally locked to the sun, so it only rotates around of 2 times over 3 turns arounds the sun, this mean extra storage for long periods or other complications (solar base power is also very complicated due low rotation speed) Mars has 2 energy values, at low latitudes solar panels are a better option than nuclear, but it will cost more than 3 times than earth for the same power and for the same level of development (mars and earth). Import and export values are based on different transport technologies, trying to figure out what should be the best case for each location (solar sails, mining ice asteroids close to orbit and using vasimr tugs, or using magnetic accelerators for those planets without much atmosphere, or using aerocapture, etc. Before start to estimate a habitat cost, that should be related to energy cost, resources cost, import cost and the type of habitat calculating how much resources will needed for person (example: for venus--> X kg of nitrogen, h2 and o2 to lift 700kg of weight allow it for each person + rooms + general sharing places, energy, etc..) so a estimation calculation base on "cost per person". If someone wants to know the reasons behind some numbers, just ask, also don't forget to provide your own estimation and reasons that might help to reduce errors on bad estimations or for reasons that I did not imagine..

Could that sailboat doing this on purpose? Is not spacex responsibility to clear up the range.. after all the requirements that different agencies ask them, they should do their part.

Maybe with this graph it will be easy to understand, this is an old Robert Forward idea for a 3 stage sail that can go and back using the same laser beam from earth.

the biggest problem with long range beaming, is accuracy and diffraction. Even with huge fresnel lenses (at jupiter distance) to focus the beam, it is no enough to the grade of magnitude that we need. As I said.. a light solar probe can accelerate very fast without laser, and brake in the target star using the same maneuver. That is the most easy and cheaper way to do an interstellar travel. It may require a lot of test and mastering in the tech, but these sails can be so light and cheap that would no matter how many times you test this to achieve an improvement in each step.

Tater: but not all neutron stars emit high radiation.. and it seems that in that book you have almost 20000 km of atmosphere to block that radiation. Is like when people said that you can no be in the edge of a black hole without spaghettify, it depends the case.. You recommend it?

I always look up for anything related to solar panels or beamed propulsion, so I am quite inform of the difficulties and the advantages for each application. For fast interplanetary travel, I would choose a microwave sail with some special layer cover that when heat up it will work as propellent. But the idea that I like more of all sail applications.. is a simple solar sail. These can be made in space very cheap and go anywhere in the solar system. They could also reach interstellar speeds to reach alpha centauri in 50 years mastering the material and technology with a close dive in the sun.

Larry niven wrote a whole novel around an habitable zone on a neutron star, is called "the smoke ring", i never read it, i will like to, if i found time. But it seems that due the right conditions, these can be a real possibility, at least there is this review that explain something about it: http://www.larryniven.net/physics/img27.shtml Not sure, I have to read it.

I did not hear, they said something about when they had the next time windows?

This is like watch game of thrones, we never know what will happen

Yes but properly speaking, we can't call something that transfers heat by contact "a radiator" It seems that you misunderstood me.. you can read my previous post if you want some context. My point was that you don't really need to trade with earth in order to achieve a thriving economy in other world. World's provide much simple solutions for a colony, a place to live self sustained with a minimum trade. A space station can work in small scale for tourism and some permanent residents, but there is no much more reason behind that, if you want to mine an asteroid, there is no need to move a whole space station to the asteroid location, just move the mining machines or move the asteroid. In fact, the first thing that cavemen did when they wanted to spread.. is search another cave and live there.. they cross over all the surface until find one.. because it was easier. What you can achieve living in orbit? yes.. it cost you less deltav to reach other place.. but you are still in nowhere even if you change location... I know, the argument is to mine asteroids from space with a whole industry that allow you to produce anything so you don't need to launch that from earth in case you want that thing up there. That has sense for the kind of people who wants to explore or be one of the few that will be needed to work there. But what about the people who just want to live in one place? Living in worlds is cheaper for those because is no cheap to make a safe self sustain space colony. In any case a industrial space station will have much more sense in venus orbit, you have more sunlight and you can capture asteroids using the thick atmosphere.

We live in a gravity well and we are just fine.. "local economies". less mobile? you still had winds on mars, dust storms cover the whole planet and those super radioactive particles would not take much time to spread over the world.. the only argument you can made is that mars already receives a lot of radiation, so maybe a little more does not do much harm... It does if you want to explore the planet or if you want to preserve any trace of bacteria life that might be. Besides, nobody owns mars.. so it will no be fair if 1 company or country ruins the planet (or help in this matter). With venus is different, everybody will be agree that is already "ruined", and wind and solar energy are a much better solution for venus. On the other hand oceans had so much mass, that a meltdown diluted in all that is not very alarming..