Tullius Posted October 23, 2016 Share Posted October 23, 2016 ITS is just SpaceX's idea how you could transport humans to Mars, without the huge costs that NASA's idea based on SLS would imply, i.e. so that a company like SpaceX may be able to pay for it. There are huge difficulties (ISRU, radiation,...) and SpaceX knows them probably better than we do, but, if they want to fulfill Musk's goal of sending people to Mars, a system like ITS is the only possibility since they as company only have so much money. If they don't succeed in surmounting these problems, they won't be able to fly to Mars with ITS or anything else. NASA has already paid 8 billion dollars for SLS and is expected to spend the same amount during the next few years. They probably won't be able to go to Mars unless they get at least 100 billion dollars to develop and build the necessary space craft, i.e. it would be just as, if not more, expensive as the Apollo program. If NASA gets the funding, they can probably do it with their technology, but it is a very big IF as in they need another space race to get the money. You'll need an awful lot of Dragon launches to ISS (133 million $ each) to earn enough money to fund a NASA style mission from the profits. So SpaceX needs a cheaper option and ITS is exactly that cheaper option. Will it work? We don't know and Musk probably not much more, but SpaceX thinks that ITS is their best option to get people to Mars in the next 10-15 years at a cost of not more than a few billion dollars. Link to comment Share on other sites More sharing options...
Northstar1989 Posted October 23, 2016 Share Posted October 23, 2016 (edited) 2 hours ago, NeverEnoughFuel!! said: So it's basically your expertise, (and many others who share your opinion), against Nasa's expertise? Sorry, but I choose NASA... my personal experience with Chernobyl was here just to illustrate danger of radiation...man, when I see that chart it's double of the amount of radiation we get here behind magnetic field shield. No, everything I said is fully supported by NASA and other organizations' research. I just happen to look at the data and draw the line somewhere different than NASA. NASA thinks a 3% lifetime risk of cancer is unacceptable, I say a 10% lifetime risk of cancer is acceptable when we're talking about colonizing another planet... It doesn't MATTER how that level of radiation exposure compares to typical Earth exposure- only if it leads to unacceptable health effects. A typical adult human will be exposed to 620 mrem of radiation a year. An Apollo astronaut was exposed to 1200 mrem in 10 days. An ISS astronaut is exposed to 7000 mrem over 6 months without ill health effects. A Mars colonist migh be exposed to 12000 mrem over a 6 month journey to Mars and that would still be OK. The victims of the Chernobyl disaster were exposed to MUCH higher doses in a much shorter period of time. It's not comparable. Regards, Northstar Edited October 23, 2016 by Northstar1989 Link to comment Share on other sites More sharing options...
Raven Industries Posted October 23, 2016 Share Posted October 23, 2016 This may be a stupid question, but could the ITS point its engines towards the sun during a solar event and just use the engines and fuel tanks as radiation shielding? Link to comment Share on other sites More sharing options...
insert_name Posted October 23, 2016 Share Posted October 23, 2016 1 hour ago, KerbalSaver said: This may be a stupid question, but could the ITS point its engines towards the sun during a solar event and just use the engines and fuel tanks as radiation shielding? Elon said that is how they are going to protect from solar radiation so yeah Link to comment Share on other sites More sharing options...
Raven Industries Posted October 23, 2016 Share Posted October 23, 2016 (edited) Oh, I wasn't aware of that. Thanks! Edited October 23, 2016 by KerbalSaver Link to comment Share on other sites More sharing options...
NeverEnoughFuel!! Posted October 23, 2016 Share Posted October 23, 2016 1 hour ago, Northstar1989 said: NASA thinks a 3% lifetime risk of cancer is unacceptable, I say a 10% lifetime risk of cancer is acceptable when we're talking about colonizing another planet... Well 10% doesn't seems much on paper... but 10% were also approximately Allied loses on D day in Normandy including dead and wounded (in our case dead and cured)... out of roughly 156 000 troops in total, 10%, or 15 600 payed the price in life or a limb (latest research counts about 4500 dead and rest of it wounded), and it was a bloodbath (very acceptable from military point of view, but let's not forget, military tolerates loses up to 25%, and at the time predictions for famous paratroopers were 70% dead) ... Forgive me but I don't like those odds... the idea of a slow bullet who will catch me 2-3 years after the (highly hypothetical, probably not in my lifetime) return from Mars with odds of survival like a guy on Omaha beach? Forget it... you would be very good general, but i wouldn't like to be in your colonization program... Link to comment Share on other sites More sharing options...
Serpens Solidus Posted October 23, 2016 Share Posted October 23, 2016 17 minutes ago, NeverEnoughFuel!! said: Well 10% doesn't seems much on paper... but 10% were also approximately Allied loses on D day in Normandy including dead and wounded (in our case dead and cured)... out of roughly 156 000 troops in total, 10%, or 15 600 payed the price in life or a limb (latest research counts about 4500 dead and rest of it wounded), and it was a bloodbath (very acceptable from military point of view, but let's not forget, military tolerates loses up to 25%, and at the time predictions for famous paratroopers were 70% dead) ... Forgive me but I don't like those odds... the idea of a slow bullet who will catch me 2-3 years after the (highly hypothetical, probably not in my lifetime) return from Mars with odds of survival like a guy on Omaha beach? Forget it... you would be very good general, but i wouldn't like to be in your colonization program... A 10% increase in lifetime cancer risk is not quite a 10% chance of dying. Unless we're talking about percentage points. Link to comment Share on other sites More sharing options...
tater Posted October 23, 2016 Share Posted October 23, 2016 1 hour ago, KerbalSaver said: This may be a stupid question, but could the ITS point its engines towards the sun during a solar event and just use the engines and fuel tanks as radiation shielding? Look at the gif I posted up the thread. It;s slightly more complicated than pointing towards the sun (which certainly puts some mass between the crew and the radiation). You have to remember that NASA has to follow rules that other employers also must follow. Hence their exposure limits. They're likely more afraid of OSHA than radiation, frankly. Link to comment Share on other sites More sharing options...
tater Posted October 23, 2016 Share Posted October 23, 2016 Anyone wanting to bounce alternate ideas off of Musk should go to the reddit AMA happening right now and simply ask him. Link to comment Share on other sites More sharing options...
RedKraken Posted October 23, 2016 Share Posted October 23, 2016 (edited) dont ask him about sanitation or comic books.....trust me! initially just to make sure we know how to land without adding a crater ..... ouch Raptor demo.... was it 1/3 scale at 100% or full-scale at 33%? and when does it fly? Edited October 23, 2016 by RedKraken Link to comment Share on other sites More sharing options...
tater Posted October 23, 2016 Share Posted October 23, 2016 (edited) Quote [–]ElonMuskOfficialCEO of SpaceX[S] 449 points 7 minutes ago* We are still far from figuring this out in detail, but the current plan is: Send Dragon scouting missions, initially just to make sure we know how to land without adding a crater and then to figure out the best way to get water for the CH4/O2 Sabatier Reaction. Heart of Gold spaceship flies to Mars loaded only with equipment to build the propellant plant. First crewed mission with equipment to build rudimentary base and complete the propellant plant. Try to double the number of flights with each Earth-Mars orbital rendezvous, which is every 26 months, until the city can grow by itself. Seems like automating the propellant plant would be the most sensible thing. Of course the ITS is sorta tricky for offloading cargo. Edited October 23, 2016 by tater Link to comment Share on other sites More sharing options...
RedKraken Posted October 23, 2016 Share Posted October 23, 2016 (edited) glass panes with carbon fiber frames to build geodesic domes on the surface developing a new metal alloy that is extremely resistant to oxidation for the hot oxygen-rich turbopump, which is operating at insane pressure to feed a 300 bar main chamber. Anything that can burn, will burn. We seem to have that under control, as the Raptor turbopump didn't show erosion in the test firings, but there is still room for optimization. Biggest question right now is sealing the carbon fiber tanks against cryo propellant with hot autogenous pressurization. The oxygen tank also has an oxidation risk problem as it is pressurized with pure, hot oxygen. Will almost certainly need to apply an inert layer of some kind. Hopefully, something that can be sprayed. If need be, will use thin sheets of invar welded together on the inside. Edited October 23, 2016 by RedKraken Link to comment Share on other sites More sharing options...
RedKraken Posted October 23, 2016 Share Posted October 23, 2016 (edited) I think we need a new name. ITS just isn't working. I'm using BFR and BFS for the rocket and spaceship, which is fine internally, but... Will aim to release details of the habitation section when we have actual live mockups. Maybe in a year or two. Probably just pack the pressurized space with cargo. Early missions will be heavily weighted towards cargo. First crewed mission would have about a dozen people, as the goal will be to build out and troubleshoot the propellant plant and Mars Base Alpha power system. Edited October 23, 2016 by RedKraken Link to comment Share on other sites More sharing options...
RedKraken Posted October 23, 2016 Share Posted October 23, 2016 SL raptor, booster hover and max g load : Approx 360 sec vacuum Isp and 290 metric tons of thrust A high acceleration landing is a lot more efficient, so there wouldn't be any hovering unless it encountered a problem or unexpected wind conditions. A rocket that lands slowly is wasting a lot of fuel. Aiming for 20 g' Link to comment Share on other sites More sharing options...
Kryten Posted October 23, 2016 Share Posted October 23, 2016 26 minutes ago, RedKraken said: Biggest question right now is sealing the carbon fiber tanks against cryo propellant with hot autogenous pressurization. The oxygen tank also has an oxidation risk problem as it is pressurized with pure, hot oxygen. Will almost certainly need to apply an inert layer of some kind. Hopefully, something that can be sprayed. If need be, will use thin sheets of invar welded together on the inside. If they haven't even got to that level in the design process, it makes the dry mass figures for BFR very questionable; and the entire architecture falls apart if the dry mass gets too high. Link to comment Share on other sites More sharing options...
RedKraken Posted October 23, 2016 Share Posted October 23, 2016 The spaceship would be limited to around 5 g's nominal, but able to take peak loads 2 to 3 times higher without breaking up. Booster would be nominal of 20 and maybe 30 to 40 without breaking up. Link to comment Share on other sites More sharing options...
kunok Posted October 23, 2016 Share Posted October 23, 2016 (edited) 32 minutes ago, RedKraken said: developing a new metal alloy that is extremely resistant to oxidation for the hot oxygen-rich turbopump, which is operating at insane pressure to feed a 300 bar main chamber. Anything that can burn, will burn. We seem to have that under control, as the Raptor turbopump didn't show erosion in the test firings, but there is still room for optimization. Biggest question right now is sealing the carbon fiber tanks against cryo propellant with hot autogenous pressurization. The oxygen tank also has an oxidation risk problem as it is pressurized with pure, hot oxygen. Will almost certainly need to apply an inert layer of some kind. Hopefully, something that can be sprayed. If need be, will use thin sheets of invar welded together on the inside. Seriously? They are still in the materials definition phase? They can't do a real mass estimation I can't get used to reddit PD: Ninjack'ed by @Kryten Edited October 23, 2016 by kunok Link to comment Share on other sites More sharing options...
RedKraken Posted October 23, 2016 Share Posted October 23, 2016 Earth EDL : Good question -- that wasn't shown at IAC. The spaceship and tanker would have split body flaps for pitch and roll. Probably just use the attitude control thrusters for yaw. Link to comment Share on other sites More sharing options...
NeverEnoughFuel!! Posted October 23, 2016 Share Posted October 23, 2016 1 hour ago, Serpens Solidus said: A 10% increase in lifetime cancer risk is not quite a 10% chance of dying. Unless we're talking about percentage points. Ok, let's try like this: we sent 100 passengers there and back, after a few years nothing happens, everybody are alive and well - GREAT, they were lucky... or their DNA was pretty resilient...(they landed in some quiet french village D day reference). We sent another tour: few years after the return 10% or ten of them gets ill, two went crazy, two went blind, six of them gets cancer, of those six we manage to cure 2 because those forms of cancer are really aggressive - total 10% causalities... (they landed in a village with a German company who is resting there after the rough time at the eastern front - D day reference)... well it's a bad luck... what can you do right? We send another tour: this time they are caught in a solar flare 50% are dead in a few hours and the rest of them (other 50%) are incapacitated for life... after the return 25-30% more dies despite all of our efforts to cure them (they landed on German panzer brigade, who was also resting from rough time in eastern front - D day reference) ... ups... bad sun forecast... So we had sent 300 people in the course of few years, and total losses are about 90 crew members short/mid/long term... let's see... wow it is almost 30% loses... is this acceptable? Point of this is, IMHO, that when NASA says 3% is unacceptable it means in fact that NASA counts that 3 out of 100 passengers will get cancer, (or some other radiation disease) for sure. Lets apply this 30% rate of failure to current air traffic... every third Airbus or 747 would crash... who would fly? Currently plane accidents hower about 1% per year (correct me if I'm wrong) but each time one of them falls it's a massive tragedy and a world news headline. Those space ships should be radiation proof, solar flare proof, everything proof (except human error/stupidity, that's impossible to defeat). Link to comment Share on other sites More sharing options...
RedKraken Posted October 23, 2016 Share Posted October 23, 2016 (edited) CF Tank constructed : Yeah, for those that know their stuff, that was really the big news The flight tank will actually be slightly longer than the development tank shown, but the same diameter. That was built with latest and greatest carbon fiber prepreg. In theory, it should hold cryogenic propellant without leaking and without a sealing linker. Early tests are promising. Will take it up to 2/3 of burst pressure on an ocean barge in the coming weeks. Edited October 23, 2016 by RedKraken Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted October 23, 2016 Share Posted October 23, 2016 2 minutes ago, RedKraken said: Will take it up to 2/3 of burst pressure on an ocean barge in the coming weeks. Dang. This really puts into perspective the forces involved. Can't wait for the failure test. Link to comment Share on other sites More sharing options...
RedKraken Posted October 23, 2016 Share Posted October 23, 2016 The big booster will have an easier time of things than Falcon, as the mass ratio of the stages is lower and it will have lower density. Net result is that it won't come in quite as hot and fast as Falcon, so Falcon should be a bounding case on the big booster. Final Falcon 9 has a lot of minor refinements that collectively are important, but uprated thrust and improved legs are the most significant. Actually, I think the F9 boosters could be used almost indefinitely, so long as there is scheduled maintenance and careful inspections. Falcon 9 Block 5 -- the final version in the series -- is the one that has the most performance and is designed for easy reuse, so it just makes sense to focus on that long term and retire the earlier versions. Block 5 starts production in about 3 months and initial flight is in 6 to 8 months, so there isn't much point in ground testing Block 3 or 4 much beyond a few reflights. Mysterious interior spherical tanks Those are the header tanks that contain the landing propellant. They are separate in order to have greater insulation and minimize boil-off, avoid sloshing on entry and not have to press up the whole main tank. Why does the booster only have one? The liquid oxygen transfer tube serves as the header tank for ox Link to comment Share on other sites More sharing options...
RedKraken Posted October 23, 2016 Share Posted October 23, 2016 It had to be 42 for important scientific and fictional reasons! The dense packing is just to max out thrust to weight, but it would be cool if there was a virtual nozzle side effect. Could this unprecedented amount of Δv (9km/s) be used to fly between Mars and Earth even outside the launch windows enforced by the synodic period, when payload mass is not a primary factor? Yes Musk AMA finished. Link to comment Share on other sites More sharing options...
tater Posted October 23, 2016 Share Posted October 23, 2016 @NeverEnoughFuel!!, that's not how the risk works. Your cancer risk over your entire life for the relevant cancers might be 5%. A 10% increase makes the risk 5.5%. We males will almost all end up with prostate cancer, for example. But when you are 90 with it, something else will likely bump you off first. Increasing cancer risk might not be a big deal. Heck, if their diet is well curated and they stay thin, Mars---radiation and all---could be a net positive, lol. Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted October 23, 2016 Share Posted October 23, 2016 1 minute ago, tater said: if their diet is well curated and they stay thin Judging by the discussion on potatoes, they may have no choice. Link to comment Share on other sites More sharing options...
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