AngelLestat

Why? there is an spy inside spacex saying that the operation, planning, ground and other related cost are so high? because if you calculate the men hours that all those process might take is not close to the men hours + hardware and materials for the cost of one stage. My guess all those cost (now) = less of 1st stage cost. And those cost can be highly reduced if you increase launch rate. I had this discussion many times with Nibb31 in the past, even today there are many signs to point this is not the case. There are no more sats because the time of delay from order to launch is still of many years and the launch cost very high. Even in this conditions, you can see that demand is growing and everyone had their hands full. Many other space applications are coming that promise massive amount of launches requirements. There is also a massive need to remove the space junk. Again, where you get those numbers? you think spacex president is lying? RCS? why a faring needs thrusters? Of course the guidance system and gps is inside a sealed container, or that is too much high tech? How the aluminum will corrode if is covered by carbon fiber and other layers? hahaha. first if you have a guide system both fairings can splash in the same place (because you force them to that), in case your helicopter has a problem, you sent a boat days after or you leave it there, there is no need to have 2 helicopters for the same task.. 3 seems more like a joke. No, because they still launch falcon heavy and if they increase the launch rate it means they need to increase 2stage production, they also can use free time to manufacture other things. 3d printing and programmed arm robots makes any production line quite dynamic. Someone smart like elon musk will be sure to exploit each resource to reduce the lazy time of machine and operators. We have an official info that said that prepare for launch and refuel a stage will cost 4 millon to spacex slashing about $18 million from the total rocket’s cost, that give you an estimate on the total 1st stage cost. And that cost does not reduce profits, so if you have another source that disprove those values please share. You are also ignoring some factors on business strategies, let me explain: You said that it will be silly to cut prices when in fact competence prices double that, but is not. Why? because a satellite is made and designed in base to the launch cost, and it takes time to make a new satellite, you can not said one day.. I will reduce cost now and instantly increase your demand. If they reduce cost now (keeping its profit) they incentivize that all companies will start to design new satellites with that cost in mind, so this reduce the chance they will change of launch provider later on, making the long term strategy of other companies fall. If you do this you get another big benefit, like you have a big difference in price and huge client fights to have an early launch access for this price, they will pay the launch cost early on so spacex will have a huge amount of money that can use to match its new launch demand. Your congrats and best wishes to spacex for the landing does not seem to match your overall opinion

Welcome to the forum Yumon.. Elon Musk was always clear about the high cost of the first stage, It was something like a 80% to 90% from the manufacture cost of both stages, which also has sense due the amount of engines and how massive it is vs the second stage. Then in december Gwynne Shotwell give us more data about the discount and why: http://qz.com/636368/the-elon-musk-special-30-off-your-flight-in-a-used-spacex-rocket/ Which also has sense for this step.. then increasing the launch rate and increasing by a lot the chance of stages recoveries, they can reduce even more the cost, because operation, planning, etc. Due experience and other factors. Is important if they can reuse the second stage, no due manufacture cost, the same for the fairings, it is due fast reusability, which also reduce all the test requirements than new stages take, that is when you achieve the higher cost reduction, a 747 would not be so cheap if once it reach an airport it will take 1 week to fly again. Of course he already said that the second stage (in the falcon9) does not worth it because it needs a lot of extra mass (shielding, legs and fuel) with a fuel which does not have much volume (reentry speed) and isp, which would be different with a hydrogen fueled second stage. Only 6.2 millons? that is something that should be dropped in your opinion? Taking into account the cost of a parachute and helicopter fuel + pilot profits? In the spacex case even if it is 1 millon (I guess is more), you need to count how much it delay your operations make new ones and then test its quality and working before use them for first time. Delay here is the main point to reduce costs, time is money... as many said.. By the way, as @sgt_flyer said, they are made with aluminum honeycomb cover with carbon fibers.. Carbon fiber dont corrode with sea water, they are very resistant to most types of corrosion. Any avionics can be in a sealed contained. Yeah it has sense now. But I wonder in what type of recovery they are planning.. I hope they choose a guided parachute like this: These fairing need a gps of course to be recovered.. so why not add two small actuators, just enough to provide a slow turn, then you set them to open at 8000m or high if is possible (with a proper slow opening), this could be enough to travel back 20 km, enough to save 40km of fuel and time for the helicopter, but the best is that you can fly both half fairings to splash in the same location. So you can recover both with 1 helicopter. With one extra change to the logistics.. instead a barge.. one fixed sea platform at medium distance from LEO and GTO recovery distance (I think the extra fuel needed is negligible), in that case you have a very solid landing site, where the helicopter can use as base, and instead move a big barge and spent energy in a fixed position, you just use some crane, to put the landing stage in a secondary boat that it will translate the stage to land.

I hear from her president that it will be a 30% discount, from 60m to 40m. ----------------------------------------- Related to the farings recovery, it seems they are very expensive, what material are they made off? In that case it has sense to recover them, you just need to attach a small parachute in each one.. My only concern (depending the material) not sure if sea water can corrode them.. About logistic spends to recovery, I guess it can be cheaper on the barge.. If they make a new barge (bigger and stable), they can transport also an helicopter, when the stage is close to go back, the helicopter take off to search the fairings, then the stage1 land and the helicopter go back with the 2 farings and land in the barge too. It may also film the landing, in the same helicopter can be the people with the job to secure the stage after landing.

ESA needs to invest in Skylon.. that is their only card for the moment.. all these "new" rockets are made just for survive these period. A lot of countries and companies are making their appearance in the space industry.. someone that always see the past will remain in the past..

this clearly buried the third landing success of blue origins way below. It makes you wonder.. Who were those?

I turned on exactly in T0 XD

If they could land in such tiny barge in those wave conditions, then anything is possible. I am expecting +95% success rate for ground attemps and also a high rate of success for sea barge landing with a new special barge (bigger and stable).

HISTORY AGAIN:: WOW:

It does not need to be under the sea, just under the ice, the same as a polar mars base. The benefic that the same ice is your structure, you can add insulation layers to enable moderate temperatures without melt the ice. I dont see any benefit for moon, anything you can do on the moon, can be using teleoperated machines or even more usefull, capturing an asteroid in a close earth orbit.. so you save all the travel to the moon. Extract water from lunar soil is not so easy either. It can be done but a lot easier and practical is from asteroids. Post 4 videos (some of them of 1 hour) without even a single comment or exact video part in which it mention the info you wanna share, that is just a way to escape the question. By the way.. I saw that documentary 2 years ago. In the time it take you search all those videos, you could easily search the amount of shield you need to reduce in a considerable way the effects of a solar flare. Well I did it, so now I can provide more accurate info: Solar Flares Treat: You will have medium solar flare every 5 to 7 years on mars or a big one every 15 to 20 years, with radiation dose of 250msv (5x the max radiation limit allowed for a nuclear worker in a year) or 1500msv for the big one. On earth orbit is different due that is closer (inverse square rule), it takes the double amount of time between solar flares, because is harder to be in the path, but they strike with double intensity. 250msv - atmosphere = 200msv in a short time, is enough to feel instant radiation poison symptoms, but nothing severe, although increase the chance of health issues on long term. By the other hand 1500msv - atmosphere= 1200msv, this is enough to kill 1/5 of the population reached (without shielding) in a month and many other with health issues in the long term. Shielding: If you want to have the same amount of radiation shielding provided it by the atmosphere, you need 11 meters of mars soil over your shelter, that is equal to 1000g/cm2 aprox. You can reduce considerably the effects with much less, but if is not enough thick, you can even increase your health risk due a secondary radiation generated when this solar flare strike your shield. There are materials rich in hydrogen that are good to prevent this secondary radiation arise like a polyethylene plastic called RFX1, water is also moderate good. https://www.nasa.gov/pdf/284275main_Radiation_HS_Mod3.pdf In the next two graphics we can see the effectiveness of shield vs some historical solar flares which total radiation dose is measured in REM, but no only depends on the total radiation, it also depends on the speed of the particles and other characteristics as we can see in the graphics. Example: you get 50g/cm2 of radiation shielding with 50cm of water shield thickness. http://www.lpi.usra.edu/lunar/documents/NTRS/collection3/NASA_TP_3079.pdf As you can see, some storms can be totally stop it with that, but some others just the half. Warning time and prediction: Here we found another issue, meanwhile more energetic (powerful) the solar flare is, shorter is the time for warning, because protons travels much faster, that was the case for 2005 solar flare which had only 3 min of warning. Other cases can be hours. Scientist can also now if one is close to happen or not, but that is still not certain, so it can generate many false positive. Book Mars radiation issue is not something we can just skip, I guess the prediction time should be increase and most habitats should be located underground with some exceptions.. Why they should be tethered? Put a bag in your head and tell me if you can still lessen.. By the way.. the suits does not need to be airtight as I said. If you can lessen noice, it helps you to feel you more like earth, on mars you will feel weird, like in space. All our senses together are the ones that shape our reality. At 50km to 55km height at latitudes lower than 60 degree, you dont have almost meridional winds, you can have 2m/s for north, but then change to 2m/s to sought.. in average.. is close to zero. But at 70km, if you are at 40 degree latitude, the meridional wind can be 10m/s, so yeah, is a big difference. In the same book Venus2, search with the tool, the word shear, it said clearly that is less than many cases in earth but constant, you can also see a shear graph in my venus resume, is there from long time ago. Turbulence cases on venus are soft vs turbulence cases on earth. For Titan, or any other under ice place, Nuclear seems a better alternative if you are care enough with safety (mostly for mars). Hydroelectric does not have any sense on Titan, because the gravity is low.. Geothermal has more sense in enceladus than on europe, but even in that case I dont see much beneftis vs nuclear.

Not sure why you post videos, the discussion has nothing to do, even your last answer did not have much sense. The question was.. Solar Flare.. in the case it reach mars from above you (so the planet does not protect you), 1/4 of the atmosphere is not enough to protect you from huge radiation doses,. The only thing that you can answer here is go underground, in case the warning time is enough to reach that place. Or shield from other way (but not using vehicles or the natural magnetic anomalies of the planet), they are not enough. We are discussing permanent stay on mars... no missions. And? you can still lessen..sounds can pass through solids.. meanwhile is not vacuum. a simple thin layer of plastic, latex, vinyl, neoprene or even any material that just keep your skin away, even if is not h2so4 resistant does not matter, because there is so little that even a normal clothe would last several days, but only helps if they can stop the tiny droplets.. Here only your ego is the problem, I cant find other explanation, after you accuse me of being wrong on 50 or 100 different things, I prove all of them without difficulty (100%), but still, no sign of recognition yet from your part. This is the info used for NASA on havoc: This was extracted from the oficial mission pdf https://www.dropbox.com/s/y5gu06h0u7n7v66/HAVOC-Final-Outbrief-General-pdf.pdf?dl=0 First to understand, if you read the pdf, it clearly said that the altitude will be 50km (and all other values like temperature and density match that altitude) You wanna know from what place they extract that graphic and values? From this book "venus 2": https://books.google.com.ar/books?id=b93lEgkPquoC&pg=PA3&source=gbs_toc_r&cad=4#v=onepage&q=eastward&f=false Page 465 and 466 You can see that in the text above the picture it said "at cloud top", "70km", "ultraviolet (wavelength that measure the top cloud section)", so this graphic is not for 50km, is for the 70km region. There is another way to prove that this graphic does not represent the 50km range. They said that the longitudinal winds at that point are 85 to 100 m/s at equator with 110 hours to circulate the planet. You can even see that they took 96m/s as average speed, only that speed can allow circle the equator in 110 hours. Well, at 50km the average longitudinal winds are 60m/s, and at 70km is 100m/s. You can check my previous post with links to see the graphics The northward wind they said that it is 5m/s, which this value represent the 70km altitude.. the real average value for 50km in the equator is close to zero. They choose the equator mainly for this error, because at lower latitudes at 70 km is very hard to counter meridional winds, but you can be at 50km, latitude 60, in that case meridional winds are close to zero, the circunference is reduce to half, the wind is a bit higher than equator, the temperature is 10 degrees less and your day/night cycle last 81 hours. They can even drag a kite or a small wind turbine to harvest energy day and night, but they dont know that, because I am the first guy in internet who come out with that idea, the same than the thermal gradient. They dont even bother to search the modern data from the probe "venus express", which is included in the venus climate pdf I shown, because the wind at cloud top was rising these last 10 years in venus. although does not change much the winds at 50km range. Fredinno? what is the next excuse?

Storm shelter? you mean mars dust storm? but we were talking about solar flares, you need a shelter against radiation, no practical vehicle can provide you that, you need at least 2 meters of dirt between you and the radiation. The question here is how much time of warning you have before the radiation reach mars. There is no wind! the sound is not carried away! If it were wind, is becoz you are not traveling at the wind speed, so this wind push you, you get an acceleration until you match the wind speed, then the apparent wind is zero. The same than a hot air balloon, they dont feel the wind, and that taking into account that earth atmosphere has more turbulence and shear. About minerals, see the table in the link I post, or search google about metals venus surface. Come on bill, you know me... You think that I lack of info about venus? I read a lot of books just to search and understand each value that I found.. I made this resume to help KSP forum users to know the most interesting info about venus without the need to read and search over many weeks as I did: The best book that I read about venus winds is this: http://www.mps.mpg.de/3183924/Dissertation_2010_Piccialli__Arianna1.pdf This is the one that help me to link very different data that I gather from different sources, at that time I did not find much agreement with different studies, then I understand and I could relate different measures to different altitude and latitudes, I notice that even the NASA team who did the Havoc mission concept, they were wrong with the zonal and meridional winds they quote for that mission requirement, which is a big difference because they would save at least half of power and storage to counter the meridional winds they claim. Answering your point: Yeah.. wind speed increase with altitude, then with different day hours (sun inclination) and other effects depending latitude. But the change is negligible in 200 meters for example, less for the height of your airship. To harvest a good wind gradient, you need at least 3 km between your ship and your Kite or Wind Turbine. Venus climate and weather is very stable, because venus rotation is very slow, so it depends on the atmosphere to equal temperatures, and it makes a perfect job, the difference in temperature at low altitude is the same no matter where you are over venus, the difference in temperature at 53km between the lower to the max latitude (day and night) is still lower than 20 degrees. Compare with earth big temperature difference... On lack of strong shear and turbulance happen because clouds are very uniform over the whole planet, this avoid temperature difference between shadows cast and sunlight, you have only 1 kind of surface (not like on earth, sea and land) which only receives 5% of the sunlight, so the vertical wind currents are negligible. You have very little water in the atmosphere, so this possibility does not happen either: Venus surface is 50km below, so any terrain effect on the wind like mountains is also negligible. So, mostly all effect that produce wind currents or gust here on earth does not exist in venus. About launch windows, you can launch at any time or day, if you choose the wind direction you save some hundreds of meters by second to reach orbit, but almost nothing, the wind always goes from east to west, so this avoid the crosswinds that sometimes you have on earth. All these conditions plus density, makes Venus the perfect place for airships or floating habitats, if you need to build airships here on earth you need big hangar to protect the airships from the winds meanwhile is on construction, there is no need there, with special procedures it become very simple. That is why I always said that Venus is perfect the way it is, although I will like more water.

How it will cause a chain reaction? Explain part by part using mixtures and amounts. If you dont have a mixture, you dont have explosion, neither ignition. Remember that hydrogen rise at 20m/s and you have the wind parameter too, so you dont get a huge hydrogen oxygen volume mix waiting to explode.

Is just an estimation made by me in base to all the info that I know about NASA toys. If it is 80% or 95% instead I does not really matters for the point.

Yes you can. There is always a solution.. the problems is for those that are making exploration far from the shelters, I dont remember the amount of time to react you have, and you will need at least 2 or 3 sats monitoring the sun close to the mercury orbit. Why cool yourself? 53km you are more than fine. You dont need airtight suits. About the wind.. what wind?? something that I always explain over and over about venus, is that if you are in a floating habitat, there is no wind, because you are traveling with the wind, so your apparent wind relative to you is close to zero. And venus has very low shear, much less than earth. They will be very visible. our eyes and brain makes can get used to big changes of light. Our brains let us see a tree shadow and the clear sky at the same time without problem, but in reality, if you take a picture, the shadow is super dark and the sky is overexposed. You can see fine on a typical overcast day here on earth, and that would be 10 to 5 times more darker than the venus surface. Venus surface: receives 20 times less light than at 53km (cloud level), this mean 5000 lux (surface). Earth on day receives 100000 lux, and a typical overcast (no the most dark ones) 1000 lux. That is not even explained.. You said scientist. ...... You know that earth atmosphere rotates in conjunction with the earth at 1200kwh? you can add +- 200kmh depending the wind with respect to earth, so when a ship re enter in the atmosphere (depending if is does from the same direction or opposite direction) it needs to brake around 25000kmh +- 1200 kwh. (or more if you are returning from mars or venus with aerocapture) In the venus case can be similar 25000kmh +- 400kmh (this is the wind rotation speed, because the surfaces rotates very slowly) Other thing, venus does not have high shears (fast change of wind), turbulance or wind shear is many times significant in earth atmosphere than on venus. haha, so you can get all your minerals from the same location? concentrations does not matter for you? You settlements are only in one place? You dont take advantage of the poles to get cheap energy or habitats? And even in the hypothetical case that you get all from one place, venus would be still cheaper due high concentrations, extra energy and the other pros. export cost is higher in venus.. but at the beginning you are more concern about import cost in which venus is lower than mars. With the time tech grow and deltav cost becomes negligible.

Because MCT development, manufacture and reusability makes it very cheap, and because Elon musk is mostly interested to reach mars, if it can get a profit of that it will be for later. So he will provide NASA a price without possible competence. silly question, my country has 25 times lower GDP than USA and is not already wasting a big part of that in military. And spacex is a USA company, so even if a country goes to mars using spacex hardware, it can be viewed as "thanks to USA" in some way. Well, at the end, only the time will tell, I bet that SpaceX hardware (rocket + ISRU lander vehicle) funded in a 90% by NASA will be used between other NASA tech to go to mars. Everybody can have his opinion, the time will decide who is right.

You could have said the same things years back about rocket and capsules that sent payload to the ISS or military USA sats, but now all that change. No it would not. In any case if NASA funds spacex hardware (at least a part) for a Mars mission, they will proceed in the same way they do with the dragon v2 cree program. Testing milestones one by one. The only fantasy here is that people will be ok with a 200 billions budget to go mars. of course, we agree. But I said it will be a 90% build in nasa facilities.. nothing more. The main point is that nobody can said that the SLS is boing, or is any of the other contractors that had a role in the construction, SLS is NASA. The same than Orion and many other things. That was my main point that you started to contradict.

I was clear in the both cases... 90% designed and build on NASA facilities. http://www.nasa.gov/pdf/664158main_sls_fs_master.pdf " Agency Partners The SLS Program at NASA’s Marshall Space Flight Center in Huntsville, Ala., has been working closely with the Orion Program, managed by NASA’s Johnson Space Center in Houston, and the Ground Systems Development and Operations Program—the operations and launch facilities— at NASA’s Kennedy Space Center in Cape Canaveral, Fla. All three programs are managed by the Explorations Systems Development Division within the Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington. The other SLS agency partners include NASA’s Ames Research Center in Moffett Field, Calif., which is responsible for physics-based analysis; NASA’s Glenn Research Center in Cleveland, which is responsible for composites research and payload fairing development; NASA’s Goddard Space Center in Greenbelt, Md., which is responsible for payloads; NASA’s Langley Research Center in Hampton, Va., which is responsible for wind tunnel testing; NASA’s Michoud Assembly Facility, which will manufacture and assemble the SLS core and upper stages, as well as the main propulsion system; and NASA’s Stennis Space Center, which is responsible for J-2X and RS-25 testing." SLS+Orion. Of course the money comes in a 100% from the NASA budget. ?? Not sure what you understand when I said "without profits", because without profits means that you dont get an extra paid from the total cost, so you dont lose money. And he gains the chance to be the only company able to lift heavy payload or sent people or cargo to mars. All the work? and who made the whole design? I said something very clear.. so if somebody disagree please disprove my exact words.

I already explain this several times.. scale.. How? hydrogen rise at 20m/s http://www.arhab.org/pdfs/h2_safety_fsheet.pdf And you have the wind factor also to spread away of the envelope any concentration. So there is no way to have a big amount of oxygen mixture enough to ignite and produce a shockwave strong enough to damage the envelope. The only thing you need to be concern, is to measure the hydrogen purity inside your airship, if it overseed the 1%, you would need to start a hydrogen purification. But if you manage to always had more pressure inside than the outside, oxygen never will enter.

As your same post notice, that is only for a certain circumstance and without measuring other spacex benefits or scores. Spacex has always higher prices when it works for nasa or government, but what real matters here is the average commercial cost, in that point no company in the world can match them. But I tell you, that if Elon Musk makes the MCT, no only it will cost much lower than the SLS, they will work without profit in this matter, because is the main goal of Elon Musk. haha.. you broke it instead of fix it I clearly said that is 90% designed and builded in NASA facilities, and that holds true. All the nasa agencies work in the SLS design over all the country, you can visit the youtube channel of each of these agencies and you will see the design process for each of the parts or stages of the SLS, I also was talking about the ORION. What are you saying, that the development of the production line and assembling will be on charge for boing and 2 different companies, but only the core stage and boosters. And they will be manufacture and build using the NASA facilities. And the main difference between SLS and falcon9, that spacex design, develop, build, administrative and operates the falcon9, they only receive support in the developing cost from NASA. So we can said clearly that SLS is a NASA rocket, the same than falcon9 is a spacex rocket even if it uses some parts or resources of other companies.

You have 3 main radiation sources in space, the main is the sun, then you have background radiation and high energy particles. As you said you have 1/2 from the horizon and 1/4 for the atmosphere, so if a solar flare happens in day time, is almost the same than if you are in open space, you can get a fatal dose, that is the main point. You dont need to, partial vacuum does not transmit very well sounds, of course in mars does not matter much because you will never be without a space suit anyway. You have day/time cycles in venus too, they last 60 or 70 hours. About land.. forget you will use soils, is a waste of space and resources, something that you can not afford in mars. Climate ? you have almost vacuum.. you may said temperature at low latitudes are similar to the antartica with a very different thermal conduction. Volcanoes? Mars is geological death, venus is like earth in that sense, it seems even more active. In venus the mountains have metals glaciers. I am still waiting your source for the "scientist who had an educated guess on mars gravity being non harmful for humans" The most close to an habitable place is venus clouds for all the things already mentioned, there is no place in the solar system more similar to earth. Because is too easy.. What hurricane winds? Venus atmosphere rotates 3 times slower than earth atmosphere, and that speed is nothing compared with reentry speed. Is not about what I like or not, is about what has sense and logic and what has not. The airships vehicles (that I call submarines just because they can go down or up in a fluid which is more dense than our atmosphere), but they are not similar in construction, design or cost, they dont need a pressure hull and these vehicles just transport the resources, they dont mine. Again if you want to compare, lets compare how much cost the transport to any floating habitat or city in venus and how much cost the transport in mars. How much cost extract heavy elements in venus or in mars? I already explain and point each of the venus pros over mars. There is no way that mars would have cheaper mining cost than venus, only you can disprove the points I made. Why industry would not settle in venus? go back few pages in this topic, I explain how a local economy works with real examples here on earth. I said that no all stochastic effects can be related or measured, and that holds true. Read exactly what is my point in that matter and the possible issues. We don't have any evidence of that, and words like "multiple studies, meta analyses" does not solve that either. I am not providing anecdotal evidence, I only supporting 1 real true.. radiation can change your dna on ways that can not be predicted, it can damage cells in similar ways. I read many studies on radiation effects, and in all those studies is mentioned all the things that escape from the study reach, because they can not be easy related or proved, or some health issues may take generations to appear. If you take that as "well nothing happens because is not mentioned, so lets drink some margaritas in mars surface with permanent stay", that is not serious enough. Now lets take the posture that you are right, and there is no other issues than the ones who could be proved in the studies, so that will decrease the life expectancy but maybe no so much. Still, you need to convince people to play lottery with their life each day. So dont try to said that mars radiation is not an issue, is clear that it would not be mars cities if we dont solve the radiation issue first. So in the poles is easier, you go under the ice, at higher latitudes would be more expensive. The same than venus has an extra cost than mars to obtain water, I am not trying to get rid of venus cons, we should include all pros and drawbacks to compare.

@insert_name No, I am not saying that.. I said to improve our climate model.. A climate model should predict and work fine in any atmosphere, like mars, venus, earth or titan. What is a climate model? just a mathematical model that we were adjusting and tunning using known physics and comparing the model and seeing what parameters or calculations gives the most accurate predictions. So you make a prediction, you set all the variables and you find if the prediction match with the reality. So if does not match, you try to corrected until it match, but earth atmosphere is just 1 case for that math model.. you need different variables in different enviroments to test your math model. Is like try to find the correct equation of a function just knowing all the values that the function has over a small range, so you dont know if the function grows or decrease beyond those values. So venus atmosphere is the holy grail for climate scientist, because they can test their climate models in a very different environment and compare the predictions with the real conditions. When they match the venus predictions keeping, then the earth predictions will improve because you are more close to the real math model to describe atmospheres.

Helium increase the cost, due its high cost and its drawbacks. At low scale may have sense as I said.. But if you increase the scale, surface cost becomes negligible, also non flammable materials are not very expensive either. Ok, joke aside, the Hindenburg burn almost in the instant just because its envelope was flammable, there is no other explanation for that, if your envelope is non flammable your original orifice or leak can not spread, never. So the amount of hydrogen leaks remains the same, you will have a flame over all your trip (in case the wind did not suffocate the flame first), but it does not matter if you have a flame, it can not spread and never will blow up, because the hydrogen is mixing with the oxygen just in that point. One side has 100% hydrogen the other 25% oxygen. I made my case here: The fact that even with low scale helium airships a lot of companies are very interested to buy them, and there are about 6 companies in the world making these new airships a reality (with many country interested like china, russia, europe community, chile, argentina, USA, Canada), the Europe community is already planning all the logistic to include these new airships. By the way, you dont need landing pads, that is the main point of these airships, they can land in almost any place, they can even unload payload without land. The time you take to load your trucks, transport that to a cargoship or to the airport, then unload that in a truck and carry that to destination taking into account traffic and other delays in each process, it makes airships very practical and cheap.

But you are only counting fatal cases, radiation effects goes beyond that, you have a Deterministic effects and Stochastic effects, the seconds happens at random with random effects. Most of those effects can not be related or detected, it can change your adn in a way you pass a fatal or nonfatal error to your children or grandchildren, or it can affect your health in many different ways. Chernobyl, Hiroshima and Nagasaki happen in places where the documentation could be hidden or was not done too seriously. Then you need a big team trying to recover all those documents with different symptoms and death circumstances, in which most of the doctors instead put the real possible cause they just note the obvious "heart stroke". (my dad as evidence who die from cancer). What are the effects of radiation in pregnant women? Or even in sperm? How a baby develops under those radiation levels? You will be calm if it was your baby the one that is growing under 240sv his/her whole life? What about solar flares? Earth and Venus had a big shield mass against those, on mars surface is similar than open space. The issue is clear, and if you want to have a permanent colony in mars, you need to at least guarantee that your habitants will not get more than 20 sv by year. Any other value or the posture of said "radiation is not a problem" is not serious enough (and you know that) Venus is more earth-like, pressure, temperature, gravity, sun radiance, sounds, thermal conduction, etc. The only that mars has similar to earth is that surface picture, but when you are there you will notice fast with your other senses that is nothing alike earth, here you are looking mars just with your eyes. Why it is more scientifically useful? In venus you can improve our climate models to understand with precision what would happen with the climate change here on earth and the best way to stop it. You can study the ground and its big atmosphere with almost no resources, because the floating habitat can be in any place of the planet without any trouble with transport. Today most of the crops does not really need soils, you can have vertical farms (which are many times more cost efficient than normal farming) using led light and in many cases no soil at all, just inserting all the nutrients using the same water. No, the deployment happens at low speeds, that is why you have a parachute.. and you have plenty of time to open. Mars does not have much water at low latitudes neither, the mining in venus would be more cheap than mars for sure. 1-venus has more heavy elements than mars 2-you can use venus temperatures to reduce the amount of energy to shape metals, in the aluminum case you will have to rise the temperature only 200 degrees, for other metals ther energy save is not much, but it helps. 3-very easy to collect those metals for any kind of floating habitat, because these habitats can be in any place they want over the planet without spending almost no energy, in mars you need infrastructure or special vehicles wasting a lot of minerals to transport those minerals to any location of need. 4-You get a lot more energy in venus, and you need energy to mine, on mars you need to use solar panels at very low efficiency storing the energy for night. 5-sulphuric acid is the chemical substance more used in industry, is perfect to separate metals in mining or many other uses, more if you use it under pressure at high temperature, they become much more effective. Is still there, I saw it! Why it matters? venus is perfect the way it is, it provides different environments and characteristics to reduce the cost of some manufacturers. Also if you are thinking in terraform mars.. haha, that is not practical at all.

It will ignite with the oxygen in the air.. There is no issue there meanwhile you have a non flammable envelope. The hole you had or leak will not spread, you will have a little flame or big flame in case the hole was caused by C4, but even with a big hole, at equal pressure with a big ship, it will take a lot of time to burn or leak enough hydrogen. The same that you will not die igniting your stove. You can control with pressure (because you also had extra hydrogen in pressurized tanks to be used as fuel) to always had higher pressure inside than outside. I also forget to answer you a previous question you made. (why you can not rise more altitude compressing the helium). The aeroscraft design use big and light pressure envelopes (1) which compress the helium at low pressure (few bars). This require low energy and is a fast process, you can had special tanks to allow 700 Bar as the fuel cells cars, but you lose more energy in the compression and it takes more time to compress. Of course your airship no only is worry in rise or go down, you need to be energy efficient and be manoeuvrable. (2) external envelope to enclose the helium (3) ballonets that are filled with external air. PDF The other kind of hybrid airships does not even compress the helium, so they depend only in aerodynamic lift and ballonets to reach a medium altitude without vent helium. Airships are fuel efficient, they can land in any relative flat location, water, ice, a rough field, etc. They can load and unload cargo without external infrastructure, they are faster than ships, trucks and even trains. They travel from point to point in straight line. Of course this is not enough to remplace other kind of transport vehicles, but for sure has its place, its niche is no small at all.

Really? what they got? They have something solid? no.. they have almost nothing yet. You even said it yourself in this next quote: NASA main objective will continue to be Mars, the last director they hired (the woman who was designing the skin suits for mars) said very clear that the main objective is mars, and she does not want to hear someone in NASA talking of something else. This does not remove the possibility that they will have different missions before, like the moon, asteroids, or even venus. But they are still searching solutions for each of the mars problems. I said this: Why they would use their own things if they can launch the mission with 1/10 of the cost or less using spacex tech? Maybe I should use will instead would, my bad there, but still: Their own things can be understood as the things that already had or almost have (SLS, ORION, etc) or things that they still need to develop. Contractors? SLS, ORION, spacesuits, heatshields, etc. is 90% design and builded in nasa facilities, and even if there is a % that is not, is still ordered by NASA using mostly NASA designs or parameters. If spacex show their designs and NASA discover that even including development for the spacex propositions (in which they will invest too) they will spend less than using SLS ORION and different planned tech, in that case is possible they choose the spacex design to travel to mars. Why they would not? Why I need to prove that spacex will supply a mars vehicle if I clearly said that as one possibility? In any case, from all the things that I read, I know that ISRU is the main goal for the MCT design, because they not include the fuel for mars departure and they even said they want to use ISRU, so if they design the rocket, and they plan to use ISRU, is not crazy to think they will use a personal manned vehicle able to land on mars that it will work with methane. In case you want to be sure, just wait few months, spacex will present their design eventually. Why taxpayer money was used for the falcon9 development and the dragonv2? I agree with all you said, but congressman are also guided for votes, if the people knows that there is an option to go mars in the short term without using an incredible amount of money, it will be hard to prove for each congressman that the other case will be better. Each time is harder to hide stuffs, take note the ULA case with the engines and the record confession. The Panama Papers, etc. The pressure of the people to do something significative now and no 30 years later. (the only time line that nasa can achieve). Elon Musk that already accomplish many incredible thing had only 1 goal, reach mars wherever it takes.. So you can make your bets, I do mines.. NASA will reach Mars using spacex vehicles.