 So, our next speaker is Markus Landgraf, who currently works for the European Space Agency. ESA, you might have heard of them, they're like the NASA of Europe. He's going to talk about space elevators because, you know, the rocket equation is pretty unforgiving and the M-drive doesn't really get you out of gravity wells. So, we might need a space elevator. Please welcome our speaker. Thank you. Who of you have heard of the space elevator? Who of you believes, keep your hands up, keep your hands up. Who of you believes to see a space elevator in their lifetime? All right, okay, I get the picture. So, most of you have heard about the space elevator and about half I would guess believe it would become reality. So, I would like to make it extra real for you tonight. It's about as real as it gets, I believe, because I'm going to talk about the elevator to the moon. Since I'm also a representative of ESA, I would also like to talk about a little bit what ESA does today to go to the moon and why to go to the moon. So, let me give just a quick overview on why and how anyone can get to the moon and then talk about why ESA goes to the moon today or how we actually do that. And then we come to the core of the talk, which is beyond rockets, going beyond rockets and of course that's the elevator. And then talk about benefits because you're a big community, you're a very successful community. What draws you here? What really draws you here is the benefits that drive you. Everybody, every one of you is looking for benefits, for fun, for knowledge, for meeting people. And the community really exists because you draw benefits from it. And that's also true for anything that we try to do in society and space exploration is part of that. And that brings me to the final point, which is the community I would also like to share a couple of links with you that will enable you to engage in the space elevator in lunar exploration in general and with ESA of course. Alright, enough said about the overview, so why the moon? This is a little fun bit that I put together and I would just read it to you. I will not comment on it because it is a bit the folklore about space and the moon. And you can form your own opinion about those things. Some of them I will also talk during my talk today. So there's this famous guy by the name of Bill Casing who of course says that Apollo was filmed at Hollywood Studio. Everybody who likes to watch British animated films knows Wallace and Gromit and they insist that the moon is made of cheese, which solves their cracker problem. Of course you all know the Apollo program that ended in 1972. So there is an issue of the Time Magazine that says soon robots will be intelligent so there is no need to risk human lives. 2010 President Obama said while talking about his vision on the space program that we have been there before and I will leave that without any comments. And there's another nice movie by the name of Iron Sky and that movie, I like that too. And then of course in that movie we have President Sarah Perlin and she says that who are these guys anyway, Nazis from the moon. So this is I think very inspirational folklore about the moon. Let's get to the real thing why we explore space. If I say we, I always am in these talks with Issa, I'm always talking about us Europeans. But the European idea is bigger than Europe so let's just feel as Europeans for a minute. Because the moon is in our exploration DNA, we Europeans are explorers and I just visited my hometown of Kassel in Hessen, a little bit south of here, a couple of last days and I took a picture there in a museum and that's a picture of 18th century artist, scientist who observed the total eclipse of the moon. And he did that under contract of a nobleman in Kassel who sponsored artist, scientist to come to his court and teach about science. So already 200 years ago and even earlier we have been really engaged in science because we understand this is part of our cultural heritage. Actually this nobleman is the grand-grand-grandson of another nobleman who hired a Swiss guy to come also to Kassel to measure the position of the stars in the sky. At the time a very difficult undertaking because the stars move in the sky due to the Earth rotation. So you have to know the time very well if you want to tell what is the position of a star because if you don't know the time it's moving all the time. So this guy, Jost Berge, made a clock and that clock was so precise and it needed a third indicator which was the indicator for the second. So the second, the time unit second was invented in my hometown of Kassel. It's not many people know that. And that shows that exploration is not only in our DNA but is also to our benefit because without the second hand on our watches we would be in trouble. Now these days we don't need them anymore. But it tells you that our everyday life is really much inspired by inspiration and inspired by exploration of course. Another reason why we should go to the moon is discoveries. Now a little bit arguing against President Obama. We have not been there. We have been in a couple of places which are very special but the moon is largely unexplored country. There's a nice book by Arlene Krotz, University Press. You can get it for cheap on any even as an e-book I believe. Let me cite him. There is a new moon. Many of the most dramatic recent discoveries in planetary science are lunar. Only in the past few years has lunar exploration accelerated again and many do not realize how rapidly our knowledge of the moon is changing. I've just put two pictures here that are from recent observations of the moon. The upper right one is a hole that was punctured by a meteorite in the roof of a cave on the moon. In the underground world of the moon we have no idea what's inside there. Of course, the first idea that comes to everybody's mind is we could live there. We could be protected from meteorites and from solar radiation. The lower image is a nice, very mysterious region called Aina. Aina is apparently the tip of an ancient volcano that blew away this dusty lid of the moon. What you see here, this more bright stuff, is probably the real surface of the moon while the rest of the real surface is still hidden under this dusty, little bit more dark, what people call the regolith. There's so much more to explore. Certainly if aliens would come to Earth and would take a couple of samples in the Sahara Desert and some in the Gobi Desert, they could not claim that they've been on Earth and have explored Earth completely. So, here's a philosophic take on it. And because it's philosophy, it has a lot of text. I will not read that. I will ask you to read it after the talk and then report back to me what you take from it. No, I will just say the basic idea. So there are two school of thoughts. One school of thoughts says there's limits to growth. Earth will run out of resources soon, so we better be very careful with them. The other school of thought, which is much less famous, says there's a limitless amount of resources because we are connected to the universe. And the latter one is called the extraterrestrial imperative, was formulated first time by Kraft Ehrige, a German philosopher, who was also part of the von Braun engineering team that went to the United States to build the moon rock. And he basically says, nature has shown to us that whenever there is a limit, evolution will overcome that limit. And he gives the example of Phytoplankton, which is a bacteria or a singular cellular organism that ran out of energy at some point, but discovered the reuse of an extraterrestrial energy source, which is the Sun. So Phytoplankton discovered by evolution how sunlight, which is extraterrestrial, could be used to make energy and store energy on Earth. And by the same token he says, human technological development is a kind of evolution and we will be able to overcome that. And how do we overcome that is pretty clear that we use resources that are not from this planet. So this is the extraterrestrial imperative. The third reason why we should use the moon is of course you see this nice gravitational well that is made by the Earth and it's difficult to get out of it because you need energy to get out. But the moon creates an extra spot there which has this interesting structure that allows to put spacecraft in an equilibrium state and put it like stations there so that you can reach the surfaces of the moon as well as deeper into the solar system. So really these three things, it's in our culture. There is new knowledge to be gained and it is a great starting point for further exploration. So these three things are our reasons to explore the moon. Why is it so hard to go there? Why did we stop? The reason is the rocket equation. This is the rocket equation formulated by Konstantin Tsikovsky in 1895. It's basically an expression of the Newtonian law of mechanics that says to each reaction you need an equal but opposite reaction and this is the only way to propel yourself in space. If I'm walking across the stage, what I'm doing is I'm pushing the stage behind me so that I'm propelled forward and the link that makes it possible for me is my soles of the shoes. If there was a slippery surface that would not allow the transmission of momentum between myself and the stage, I would just slip and fall. But in that case, I would have to use reaction principle of Newton to propel myself. In this formula, there is a very important parameter. It's the delta V on the left-hand side which gives you the amount of how much you have to change your velocity to reach a certain target. In the lower part, you see the numbers here that are not very important, but it's very difficult to get from Earth into low Earth orbit, which is the first little gravestone there and then 3,200 meters per second to go to the lunar vicinity and then on top to go to lunar orbit where you need another 800 and then to the surface of the Moon you need 2,000. If you know that our current technology limits us to use exhaust velocities, which is the VE there, of less than 5,000 meters per second, tells you why we need big rockets to launch small payloads. We need a 700-tonne Arian-5 rocket to launch a 10-tonne satellite into geostationary transfer orbit. And that makes it so expensive. Now, expensive means what is the economics of space transportation? And what you see on the right-hand side is much more interesting. This is a table of how much it costs today if you would go to a launch service provider to launch your stuff into space. In Earth orbits it's about 10,000 euros. Into this lunar space it's 10 times that, so 100,000. To lunar orbit, 200,000. Down to the surface of the Moon, 1 million euro, 1 kilo. To bring anything back from the Moon, 10 million euros. So if you even would get back platinum or the most precious stuff that you can think of, it's still cheaper to get it on Earth. So forget about the space economy with rockets. That will not work. The only thing that the private sector can do is they can make space travel more efficient so that for the governmental players everything becomes a little bit cheaper. But they will never be able to get stuff from the Moon and sell it here on Earth. That's just physically impossible if they use rockets. On the left-hand side you see that actually the cost raises with the square root of the mass. So if you have a big rocket it's more expensive, but the rate of increase is lower than one. So that means that for each kilo you pay less if you have a big rocket. And that's why Arian V is, for example, bigger than Arian IV. So this is the economics of space transportation in this situation that we have today. And in that situation ESA has a program that takes us, indeed, to the Moon. And I think just two slides about how ESA goes to the Moon today. Like I said, the biggest problem is gaining access to the Moon. And that is why there is the big blob. And then there is the little bit smaller but still challenging problem of surface operations. And these two problems really break down into smaller bits. We need to get to the Moon we need staging so we have to change the vehicle let some stages that already spent their fuel go away so that everything is lighter. Then we need landing which is difficult because it's difficult to rain. And then we also have to launch from the Moon which is something that is incredibly difficult given the fact that already launching from Earth is difficult. And then you can break it down further and each of these topical problems ESA has a program. For example, to get humans, astronauts go to SysLuna space. We are cooperating with NASA to build a human space vehicle that will launch first time in 2018 around the Moon. ESA proposes a program to build a habitation module for this SysLuna habitat. This is a habitation staging post in the SysLuna space that will enable access to the lunar surface but also into deeper space. Then ESA works together with Roscosmos, the Russian space agency to build a landing system for lunar applications and there is a camera that will first go in 2019 to prepare our technology for landing on the Moon. And then further down the road, we're working together with an international consortium or with international partners to build a demonstrator mission that does everything. So we land, we take off and we have a little rover that shows mobility on the surface. And this is an integrated system that we are currently proposing to our member states. And ESA would like to play the part of the ascent, getting away from the Moon, launching a rocket from the Moon is the problem here. And then the final problem that we face is habitation on the lunar surface and that is of course challenging. Perhaps not as challenging as habitation in free space but still there's difficult problems. Another topic that still needs to be addressed is getting resources from the Moon not necessarily to make money from it like I explained, it's probably not going to be a good business but we already have a payload that tells us how we could use resources to sustain a base on the lunar surface. Now this is a little bit of a time arrow here to show you how we want to develop that over time. So the first thing is like I showed this is the drill and the camera and that goes already in 2018 and 2021 in two missions together with Cosmos. Then there's the Orion Vehicle, first launch in 2018 the first human mission in 21. Then the SIS-LUNA habitat going to be built up somewhere around the mid-2020s perhaps a little bit earlier and then this interesting demonstration mission in the mid-2020s and then ESA does indeed plan or propose in cooperation with international partners to have a human mission or a series of human missions to the Moon to really start the exploration. But all of that is still limited by our transportation problem but that's what we can do today like I promised that's the realism of the situation right now but let's go beyond this let's go beyond rockets when I said that we can propel ourselves only in space, only by pushing something back aqueous-reaction I lied a bit so I was not completely honest to you guys because if you have a physical connection to the planetary body that you're orbiting then you can transmit momentum and that physical connection is created by a space elevator and the basic principle I think really many people in the room already know it so I will skip through it quite quickly the idea is to have a long rope and the rope has a center of mass and that center of mass is orbiting the planet in sync with the planet's rotation so in the end the rope will touch the surface of the planet but will not necessarily exert a force in it so it's simply like a satellite but it's going around the planet at the same rate as the planet is rotating and then you can climb up and down that rope with the cabin you make a nice cabin around you with air and you can go up and down and I know your heads are full of questions and I try to answer some of them and certainly the broader space elevator community can answer most questions today so just as a start the energy actually is not so much the problem indeed we still have to provide the energy to go from Earth's surface up into the gravity well but that's only one kilowatt hour per kilogram and how much is kilowatt hour in Germany today is like 40 cent I guess it's twice the price than in France but never mind it's still cheap enough right then the climber can go up and down with electric energy has electric motors attached to that cable can go up and down the cable is actually kept taught by the forces of gravity and centrifugal force so gravity pulls the part to the left down and centrifugal force pulls it to the right up so that the cable is always taught then of course as the climber goes up and down the climber creates what's called the Coriolis force and it puts the sideways force on the cable and the sideways force creates a wave in the cable and what does the wave do? not much because of the high tension on the cable and then left hand side you see a couple of wiggly lines which is the free motion of the elevator and if you can read the small numbers we're talking about 700 meters of maximum amplitude of that and if you go to higher vibrational modes it's really not causing a lot of vibration in terms of spatial vibration of course the cable for Earth and this is the Earth cable would be 154,000 kilometers long so this is not to scale 154,000 kilometers in the y-axis you have just kilometers and you see that this is the free motion of the cable and by introducing a little bit of wiggle on the base of the cable you can even manage that vibration so if you have a vibration on it you can cancel it out so no problem and the other side shows you what happens if the climber goes up and this is actually on the moon cable it's taken from a paper by Pearson where when the climber goes up you will have a bit of oscillation in the order of a couple of meters normally but it's certainly manageable so let's talk about strong cables because we need strong cables to kind of not make them rupture so what's the strong material I like to express strength of a cable in terms of rupture length because it expresses the strength of the cable at the same time as its specific weight the rupture length is the length of a cable you can suspend it vertically in a 1G, constant 1G without it snapping under its own weight so steel cables are pretty strong you can have 11 kilometers if you make a 12 it would just go bang because of its own weight carbon fiber goes up to 330 kilometers and a mystical material that's called multi-wall nanotube that exists only in laboratories in very small quantities makes it up to 3,300 kilometers for earth for earth elevator you need about 2,500 kilometers of rupture length so this mystical material would be able to do the earth elevator so on the right hand side you see other materials that are available today and you see somewhere figures about 150 to 500 kilometers rupture length the longer the better why does that why is that important because the magic of the taper people have been asking how strong does the cable have to be to make a space elevator and there was a paper by Jeremy Pearson in Akta Astronautica 1975 and he explains you can do it from any material you can even make it from steel only you have to make it much thicker at the center of gravity than you make it at the base now these taper ratios how that is called becomes so extreme for the earth that for weak materials that the elevator becomes not feasible so I show you this magical multi-wall nanotube material that allows to have a space elevator from earth with a taper ratio of about 8 or so material that exists today is for example carbon fiber or the famous honeycomb polymer so that these are fibers you can buy in the shop today and you can see for earth it would be like thousands of time thicker and it's not a problem of making something thicker but if you make something you start with say a centimeter and you have to make it 10,000 centimeters wide at this widest point and the whole thing 144,000 kilometers long the total mass of this thing becomes humongous so that's not going to work so but for moon and mars this is much easier you can see and the reasons of course that moon and mars have lower gravity and they have slower rotational rates than the earth and then you end up saying that with existing materials if I have a taper ratio of about 8 or 5 or 4 I can make an elevator so why are space elevators easier on the moon than on earth we have a feasible ribbon material now we call this thing a ribbon and I will come back to why we call the rope a ribbon we have very few artificial satellites around the moon that could potentially collide with the cable and we have no human-made space debris around the moon and there is no atmosphere on the moon that could kind of damage the cable and there is no strong, trapped radiation because there is no magnetic field around the moon so the elevator around earth is quite futuristic it is quite science fiction but the elevator around the moon it is still science fiction but it's closer so it's not 2031 it's 2001 so if you compare the movies you can see right so one word about the climber I know that the climber is the most inspiring part of the space elevator but it's by far not the biggest problem and in my life I've always tried to crack the thickest nut first so one day when somebody gives me that cable I will start talking about the climber but there is a nice concept out there that basically runs onto wheels and you have electric motor and you have solar arrays providing the energy and you can have a couple of capsules attached to it that transport the payload so what is it that we get out of the moon elevator why should we do it beyond exploring the moon well first of all you remember that diagram right made us a lot of headaches and stomach ache but if you have space elevator you can do this because you can go from moon orbit to the lunar surface so this change in velocity that you need to make in order to go from moon orbit down to the surface all of a sudden goes away so your rocket has to do much less work not only that only this number goes away another 800 meters per second and the rocket makes even less work so all you have to do is basically now you have to launch an arian 5 rocket you get 7 tons to the lunar surface today with an arian 5 you get about 500 kilos so less than yeah roughly 10% of it but if we had let's speculate a bit if we had also an earth elevator we could also cancel those two figures so the number that you see for delta v becomes 0 that means you can have a free transfer from the earth surface to the lunar surface no propellant needed and I'll show you in a minute how that looks like not in a minute, I'll show it to you now right this is a computer program it's publicly available on the web and I have the URL shared with you on my website and what I've done, I've played with it and you see in the crosshair you see the earth and downward pointing is the earth elevator and on this central ring you see the moon with the long line extending with the blue dot at the end that's the moon elevator now I put a payload that's the little green dot down there let me find my cursor so I can play with it there is my payload so now I'm starting to let the earth rotate and you see the time scale up there is 512 so it's a factor of 512 over real time so the earth rotates and the payload goes with the elevator of course and while the earth rotates of course the moon is moving slightly but much less fast when this reaches the 90 degree position so this payload will just be detached from the cable and then this will describe a freefall trajectory to wherever it takes it because of the loss of gravitation and then now I've sped it up to 8192 to make it a little bit faster so you don't have to wait to sit here all evening because things as they go farther away from earth they go slower and then what you can do and you see now every turn of the earth today is that at some point you find a trajectory where this object can fly around a voo with your moon elevator and you can just latch on and then descend on the moon elevator all the way to the lunar surface so you would have a direct connection from the earth to the moon and the other way around bring any material platinum, gold from the lunar surface back to earth without any use of propellant and of course what that would do is to enable us to make real use of space economic use of space we could create structures that are so humongous that they would just collect enough sunlight for example 24-7 to provide earth with energy this is a little animation showing how you can make space waves to beam the energy down to the earth surface and you can make these structures you can make space hotels because all of a sudden you've broken this you hacked celestial mechanics and I think that's the basic idea this is why there is interest in the space elevator so my final thought here is that to engage in space exploration and the moon exploration and I would also like to point you towards the talk by my boss actually Jan Werner the director general of ESA at 8 o'clock in room number one and he will talk about the moon village and how this community will make it happen that we will engage into lunar exploration and final word on the community of links, emails, Twitter names and URLs that you can use when you download the presentation to make it happen and be part of the space elevator thank you we have a rather generous half hour for Q&A so please get ready to queue the microphones for questions there's basically microphones everywhere so just queue and also of course as always we have questions from the internet so if you're in the chat watching the stream we'll take care of you as well we'll just start with microphone 2 please hello thank you very much for your talk so what I was wondering is that you did not mention at all if there is going to be an extra problem that the cable will have to take care of that is the stretching due to the difference in gravity that goes along the gravity well is that going to be a problem or is that a very minor factor thanks for the question I hid that of course and the answer is that the pierce model is made such that the tension on the cable is constant through the cable by making it thicker at the place of the biggest force because you know tension equals force divided by cross section and then that's taken care of before we get to the next question just a little announcement please try to be quiet and if you need to leave leave very very quietly and if you don't have to leave very urgently just do us a courtesy and wait until the end of the talk, thank you could we get an internet question please could we get the microphone please question working is it already known how the elevator affects the earth rotation it does not at all there is of course a small value you know that by nature the earth speeds up when it contracts because of it's cooling down but normally it slows down because of the presence of the moon attaching a lunar cable of about a thousand tons will not affect any because the moon is much more heavy could we get microphone number 7 please my question is what will this mean for future further space exploration missions that what are the implications for further space exploration missions starting from the moon or does that have any implications for this thanks for the question yes there are and of course that's part of the deal that we try to prepare deeper space missions by making propellant on the lunar surface transporting it into a system of space which could be then a starting point for Mars missions or Jupiter missions or even at some point missions to Proxima Centauri but I that's an extra talk thank you mic number one please thank you for a great talk I'll try to keep the question brief and feel free to direct me to the next talk by your boss if you feel like he could answer the question better but it seems to me that most of the reasons for going to the moon apart from the science of course which is important could be solved easier from low earth orbit I'm thinking specifically of refueling spacecrafts and I believe that low earth orbit fuel depots could be refueled from asteroids and you wouldn't need to build a space elevator on the moon with you 100% and of course my boss can answer any question better than I can but let me give it a try let me give it a try of course that's actually my day job so I'm looking at architectures of exploration to find out what's the best way and you're right if your goal was to have a Mars mission or a series of Mars missions that use refueling perhaps not use fuel from the lunar surface you would use asteroids and transport the material not necessarily to low earth orbit because of the high delta V penalty but you're right there's competing things and the real reason for this lunar elevator to just make it clear is if you want to exploit the moon economically for not necessarily use it for further space exploration but for bringing precious metal to the earth that's the real reason for the lunar elevator but do we not also have access to those materials in the asteroids not necessarily if you have to bring it if you have to bring it out of interplanetary space because you have to then fly a reentry trajectory and that is very expensive but let's take that offline sure thank you do we have internet questions yes why are carbon nanotubes or graphene so bad materials can you repeat please I didn't catch that okay carbon nanotubes or graphene has been materials that have been talked about a lot where there's so bad materials for the elevator no they're good materials but they're not there yet that's the thing I gave a talk in 2013 on TEDx whoever wants to google Landgraaf space elevator finds that on youtube and there I'm talking about how to make that possible and you can tell from my talk back then that I was a little bit younger at the time and a little bit uncertain and that's why and that's exactly the reason is that the nanotubes are not there yet so thanks for the question number 8 please so hi up here you talked about that we have the material to build a lunar moon elevator but not the earth one so is it possible to make the earth cable just shorter and then use a rocket to connect to the lower part of the elevator that is true and you were invited to give a talk next year about that it's there's a whole community out there about space tethers and yes there's options but there is sometimes risky you have to fly around the world with the end of the cable and isa even was involved in tetherer experiments back in the 90s so yes there is a community out there that trades makes it possible but the real benefit that solves a lot of operational problem is when you create a real elevator that actually attaches to the celestial celestial body I have a follow up question if you have a space tether don't you need fuel on board to reposition it otherwise it flies away or it come back correct that is correct and normally people solve that problem by making a low thrust transfer using electric propulsion or using the earth magnetic field by putting in electric power so there's all kinds of solutions for that could we get number six please when you travel to the moon an obvious advantage of rocket based transportation is that you can more or less freely choose the point of your landing so would that space elevator concept allow to reposition the elevator so you can more freely choose where you are going yes there is a paper that I am citing also in this talk by Pearson in 2005 or 2008 where they basically connect the elevator to a tramway so they bend the elevator a bit higher latitudes and then starting from that higher latitude points to a tramway but in any case you can once you are on the surface you can drive I mean take your all wheel drive and just go there is more easy solutions to that than with a rocket and you are right with a rocket you can choose your landing site freely could we get mic number three please yes I have a question about the failure state and how it differs for a earth cable and the moon cable so I would guess an earth cable would burn up in the atmosphere if something goes wrong what would it be for a moon cable so first of all the moon cable if it disconnects so that there is one part coming back it would just impact lunar surface and be destroyed upon impact normally with hypervelocity impacts you get complete obliteration the material and about only 10% or even 5% stay on the surface the rest goes into the solar wind but that doesn't have to take place you can always sever the cable on purpose when you have a break and there are a couple of other reasons that I didn't explain in my talk why potentially you can make it so that the cable never breaks mic number four please I saw in your slides that the calculations about the cable wobble were taken with elevator speeds of about 250 km per hour calculating that the cable from earth would be about 150,000 km long I make that 4.5 weeks around that so the whole transfer would take multiple months are there any plans on sending humans up with that space elevator or would rockets be like cheaper because they are faster the only reason we have unmanned space program is because you cannot make small humans and if you have a system that is so capable like the space elevator you would take humans from day one so yes and they would just have the food for 5 months well technically we have small humans very small humans could we get another question from the internet please yes how about the voltage generated by the magnetic field of the elevator would it be a risk or another source of energy both for the earth elevator it could be a source of energy or depending on the material you choose but for the moon elevator there is no voltage because there is no global magnetic field around the moon number 8 please you said a space elevator from earth is not possible with materials we know what is about a launch loop or something like that so you are talking about you try to connect both ends of cable to the earth and ah ok I haven't looked at that concept never heard of it but thanks for the inspiration I will look it up launch loop you said both ends on the earth and then with centrifugal force you can the tension will probably be the same but let me check it out sounds interesting thank you could we get number 3 please coming back to your question from the beginning whether we will see this in our lifetime or not can you give an estimate maybe an optimistic or realistic estimate on the timeline how far is the research so if I was president of the world we will have it in 2050 it really depends very much on the decisions that are taken on the global scale in these days just look at the new US administration and some movements here in Europe that are detrimental to the efforts of gaining more knowledge but if we take the path of knowledge I'm pretty sure that we'll have ESA plans to have a moon program in the 2030s and the moon village will be implemented that Jan Werner will talk about I'm pretty sure we'll have a permanent settlement on the moon somewhere in the mid 2030s and then the necessity of having an efficient transport system will force people to build a space elevator and that will be then 2050 and I plan on being around that long mic number four please on the topic of focusing resources so we talked about the cost effectiveness of rockets but we didn't talk about reusable rockets as pushed for now by Elon Musk and SpaceX I was wondering if you could talk about the cost effectiveness of reusable rockets versus space elevators in terms of focusing our resources that we have currently here we know from Elon that reusable rockets are about 30% better than non-reusable ones right so that brings down anything back to the moon from 10 million to 900 9 million 700,000 per kilogram so that's great but it's still rocket technology the space elevators are estimated to lower a factor of 100 now that includes the initial investment but assuming that the initial investment will be less than 10% of the turnover so the turnover of course you have to put a lot of business in it to make it work and that's the problem with the space elevator if there is not enough business for it to do then people will never get into it mic number 6 please so thanks for the talk at first and so from our talk I guess that the moon elevator is currently already technically feasible or buildable so are there any plans or what's the timeline the ESA does not have a space elevator program we have made a couple of experiments with space tethers we're quite successful and we have that in our knowledge base the reason why ESA is not engaging in it is because our task is to enable research for our member states and research is not the prime target of the space elevator there is a space elevator consortium and you will find something on the for example here the one that I showed the liftport.com you will find that they have a timeline in them for the private consortium and their plan is to make a business case for the space elevator okay thanks mic number 2 please thank you at first thank you for the nice talk I have the question there is often the argument that we shouldn't engage in human space travel because of the cost and the risks and it's really really hard what would you give as an argument against that I'm in space business since 16 years so I have answered that question a couple of times so forgive me if I feel a little bit superior at this stage so first of all the cost is not tremendously high and don't forget any euro that you put in a space program does not go to space the euro stays here and we've done a benefit analysis by ESA that roughly for each euro invested by our member states they get 5 euros back they can tell you about the details if you want the second thing is that space is right now we're looking at about 1% or much less than 1% of national spending it's not a big part of the national budget the third point about the risk is human space flight risk is really only to the astronauts and they have a contract that says you have a risky job are you ready to take that risk anyway so that's the risk bit and that was it right also the point that we can do it without humans or people tell me I'm not really behind this tell me we can do it without humans so why don't we do it I cannot exclude that possibility that someday we will have intelligent machines but I've tried to I've fooled a security camera the other day by just having my glass my shades hanging out of my mouth not putting them on just put them in your mouth no security camera will recognize your face so that tells you there is not intelligent computers today because the security sector has billions and billions of euros to spend on this stuff like I said in my beginning in 1972 there was an article which said that there will be intelligent robots very soon and I'm still waiting for them but it could be there in 20 years no, it could be thank you could we get the internet please if this is a quite practical question how would you deploy and fix the cable yeah that's a brilliant question and I skipped that in my talk and apologies for that and that's why the question is why would you deploy a rocket so a rocket would bring roughly a 100 to a 1000 ton cable to the vibration point to this stable point that I showed before and then from that point on the cable would be deployed at the same rate upwards and downwards maintaining the center of gravity at that stable point and doing a little bit of station keeping not too much and then a little rocket very small one with the climber and fly around the world, attach it and then it could go up and down any time so it's really and I would refer the the person who has asked the question also to the space elevator wiki that I'm listing here on my links because there is some information there mic number three please hi I have two questions the first one is are we transporting materials from earth to moon or are we going to mine it from there and the second question is how are we going to build the cable are we using like 3D printers so first part of the question both options exist so you can bring everything from earth there that's the more expensive way but the more safe way the alternative is you bring a small pilot cable and then you start building strands of the cable and pull it along the pilot cable up and then make a thicker cable out of the pilot cable that's the cheaper and less risky one and yes 3D printing is definitely an option and I actually deleted one slide that showed how the structure of the cable is because I wanted more of your question so I deleted slides so the idea is to have like a crisscrossing set of strands that would allow a breakage of one strand without the cable breaking or you can make it the breakage of five strands without breaking of the cable and by that way and also that would allow then crews to go up and fix the cable if there's a broken strand they would go up, desplies the cable and then get the strand out insert the new splice and pull a new cable thing and adjust the tension on it thanks welcome could we get number 6 please as I see Clarke have written a book Fountain of Paradise where he described elevator concept and they have many papers written about this concept to using hyperbolic structures like all independent all in drilling platform are using it also and I would like to know have you already calculated an equation how much time would it take to lift up a human being from earth to moon and with the global space exploration strategy is this because it looks like the international space patient will be up until 2025 at least the financing is secured until then and what it will be after next is it also possible to use CISS for as a springboard as is often mentioned to the moon thanks so three parts right so yes I know Fountain of Paradise a very good book and it's really about the economic and socio economic impact of a space elevator so that's very interesting thanks for mentioning that now the technical solutions and discussions that are in this book and Arthur C. Clarke is an engineer are very interesting and honestly I haven't looked into them so very much there's a lot of interesting solutions there for the anchor point the second part of the question was about the travel time and that was answered by a colleague before so we're talking about months if you have a slow elevator you can speed it up you know you're in vacuum so you can go a thousand kilometers an hour without too much damaging your haircut so that would work so cut it down from couple of months to a couple weeks and the third question was the global space exploration is the International Space Exploration Coordination Group and thanks for that question because in that group we're preparing the next steps ESA together with NASA with Roscosmos with the Chinese Space Agency and the next step will very likely be the creation of a small staging outpost in CISLUNA space could we get microphone number one please yeah okay thank you two small questions the first one might seem a little naive but once the elevator is in place to climb up the elevator wouldn't that apply a downward momentum how do you keep the rope in place right yes but it's so small for a one ton cabin you would have a thousand ton cable no it's a two ton the two ton climber would have a thousand ton cable simply because of the math how it works out and you can check the papers so the COG would go a little bit lower and you can compensate that by a little bit of motion below it's intricate so the horizontal motion by a mobile platform that travels a hundred meters on the lunar surface can compensate can provide the energy to attach it once you have attached this cabin then it climbs up and the COG will approach again its original state but these are manual changes and mainly they cause oscillations that didn't have to be managed in horizontal mode okay and the other question was say we managed to build an elevator on the moon but the whole technical thing for the earth just doesn't work out and so we are stuck with just an elevator on the moon how useful would that actually be so the usefulness of that let me get back to that image is this so you cut the delta V in half enabling reusable rockets going to and from the moon about half as expensive as it is today so you're cutting from 10 million to 5 million is that enough for economy? I don't know so it would be better but it wouldn't solve the problem at all okay thank you number two please so you talked about economy and I wondered is there any consensus about who owns the moon or may we face the next war on resources in the future? there is a consensus officially by the UN which means that nobody can no nation can own the moon and that includes by the way private companies because each private company has to have its legal framework set up by a nation but of course things always go different than the official ways and already now there is a lot of discussion about who owns the moon and how to wait for the war maybe that's a chance to occupy the moon could we get a question from the internet traveling from moon back to earth via elevator would you mainly use the atmosphere to break or would you have to have some propellant you don't need either because when you go down on the cable you will be co-rotating with earth so unless there is a high altitude wind there will be no friction with the atmosphere basically the air will become ever denser as you go down basically the first 140 140 oh man 130,000 this mass on stage is just terrible mental mass on stage you should try it one day so the first 99.999% of the cable you will be in vacuum and then the last bit last 30 kilometers so you know 144,000 minus 30 last 30 kilometers you would be in the air and then you would feel the air becoming thicker and of course high in the atmosphere you have some winds you know you have the jet stream but at that stage you will still be in your little cabin until you reach about 3,000 meters when you can basically get off the lift if you want one last question from number one please make it short if you can thank you Mr. President for the nice talk actually my question is quite similar to the one from Mike too just now but not the question who would own the moon but who would own the elevator because if you're not the president of the world obviously in space things go far better together than on earth like an ISS and something but due to the cost of the elevator what do you think will it be a public project like with ESA and NASA or will it be something like SpaceX on private investors that's a very interesting question I really haven't thought this through but my answer would be very likely it's going to be private because the benefits are really entrepreneur benefits by getting material from the moon or building big infrastructures in space that offer services so I would guess would be private and then your question is very relevant because it's a huge powerful piece of infrastructure is that even possible to have a private entity owning it without interfering with national interest and national strategic interests because in the end you could bomb any place on the earth from that elevator if you want so perhaps some nations are not very happy to have a private company controlling this thing and that is a little bit also addressed if you read Arthur C. Clarke's fountain of paradise because then this whole problem becomes very clear and I don't have a good answer for you sorry so we are out of time please thank our future president