 What do you think about when I say space and airborne laser platforms? Death Star? What else? What do you think about when I say laser-based propulsion for space travel? Freaking complicated navigation math with way too many variables. Okay, no seriously. In the next talks we will learn what's really behind those terms. Peter Buschkamp will teach us not only basic physics, but he will also teach us about the boundaries of lasers in space. And we will learn about space travel with lasers, which absolutely sounds like science fiction. We will hear about space travel with lasers, which sounds like science fiction. Peter Buschkamp works in the infrared group of Max Klang's Institute for Extraterrestrial Physics, where he builds the most sensitive instruments in the world for world-time observation. He is active in the Freifunk-community in Munich, in the background, and he also leads the public observatory in Bielefeld. The director comes from Bielefeld and finds Bielefeld very boring. I was born there. Please give a big applause for Peter Buschkamp, who studied in Bielefeld. All right. Okay, yeah. This is a follow-up talk from last year. I don't know who was there at the time. I talked about how you can shoot lasers into space, and how you can use them for astronomical purposes, in order to compare the atmosphere, the destruction of the atmosphere, to get clean images on the ground, and not just from a world-time telescope. So this time it's about laser in space. It's only 30 minutes, unfortunately. I will give a brief insight into some topics that are already flying above our heads and what some people think of how I have to fly in a short time, and other things are pure speculation. So first of all, we're going to talk about laser drive. This is, basically, the second reason why this talk was created. I was talking to Les and he wanted to talk a little bit about interstellar and interplanetary recolonization. So I thought, cool, maybe you can combine that, and then we'll talk about photonic propulsion and such things, and then maybe we'll have more time for the first talk. Okay, then we'll talk about laser beams, how you can clean the sky with lasers. It's about laser sensorics, which are what you look up the weather on your smartphone, so that you can use them every day if you look up the weather on your smartphone, so that you can use them every day if you look up the weather on your smartphone, so that you can use them every day if you look up the weather on your smartphone, so that you can use them every day if you look up the weather on your smartphone, so that you can use them every day if you look up the weather on your smartphone, so that you can use them every day if you look up the weather on your smartphone, so that you can use them every day if you look up the weather on your smartphone, so that you can use them every day if you look up the weather on your smartphone, so that you can use them every day if you So first let's talk about laser propulsion. Laser propulsion is a method of pushing something forward, just with the help of light. How does that work? Well, photons are not just there to illuminate things. They can do that very, very well. But they also have an impulse. Just a very, very small impulse. Energy is divided by the energy. But there is a bit of impulse that is transmitted by a photon when this proton hits a surface. And to get an idea how big that is, if you are in an atomized band, then you get the amount of photons in the sun that corresponds to the solar constant. That's about 1361, I think. I think I remember. Watt per square meter. And this is then translated when you use a solar sail that you bring into an atomized band and just the photons of the sun that are transmitted. What then corresponds to, well, it depends on the orientation of the sail and whether it is a black sail that absorbs photons or knows what it reflects. So whether you have an unethical relationship between the solar sail and the solar sail. So whether you have an inelastic or an elastic impulse for the physicist. But roughly you get around 7 micronutons of thrust. That's not a lot. But you can scale it up. Maybe the sail, not just one square meter, but maybe 100 times 100 meters. The point is, it's just a very, very small fraction of every photon. But on the one hand, there are a lot of photons and on the other hand, it's free of charge. If you have a space mission in which you move very far away and you have time available, then if you want to do something like that, then maybe what you want to do is constant. It can burn chemical rockets in a short time. You don't have to put a lot of fuel into an atomized band. This could be an option. Is that pure science fiction? No, actually not. This here is a representation of a test solar sail satellite from a Japanese space agency that took place in 2010. The Icarus is the name. And that gives you a rough idea of how it looks like. This is just a sail with something in the middle. But here, this is actually flying now at the moment. They recently communicated with it in 2014 and they hope that the next communication can take place next year. And what you see here is in the middle you have this little payload, a few experiments, a transmitter that communicates with the air and these blue stripes that you see around the middle, these are actually solar cells that create the electricity for the experiment. How big is this thing? 4 x 4 meters? This is a very nice technical demonstration. Of course, if you really want to go into serious propulsion with that, then you rather think of a 100 meter to a kilometer big sail. We don't have a real clue how to make this happen and bring it into the space. But what you use as material, how you combine it and where you get into it. But what you think about is not the sun, but of course you could put a big laser on it, for example from the earth or the space. There is the project Star Shot that goes through the media really well and it's a very interesting concept that a laser on the ground or in the space and there you have a direct laser light and it doesn't have this distance from the sun if you get away from the sun. So this is an option, another option with lasers similar to that but similar to that is not only pushing the sail forward but also using the laser for energy. So here we have a laser drive with an energised laser drive that's not a sail on the very left you see a laser array here on the left you see a laser array a series of lasers made on a Jupiter moon I think it should be because of the geysers so this laser sends a strong beam and it looks like a reflector and in the front we have the payload we have the machine and so on and so what we have here is we have the fuel but unlike in a chemical rocket where the fuel is used for the energy and the the dust and what comes out in this case an external energy source is used for a fuel that is then pushed out from the dust of our fuel system and that pushes it forward so if you think of a normal jet it's the same the air is the medium and you use kerosene as an energy source to push the air and the other very interesting thing here that is in discussion in the literature is the so called so called photonic laser thruster for some applications also military applications which the wish here is to have a satellite information flight that may be like flying together here and then be able to get together again and get together again for radar interferometry radar on the ground these kind of things this can be done with simply with satellites with a rope in between but if you have small satellites then you might want to think about something else and then you can use a laser for space vehicles the mission vehicle and the resource vehicle the interesting thing here is you use the photons you just look at a reflecting surface like a sail or as in the other case but you have a kind of laser cave there are mirrors on both sides and you use the photons and this is very efficient you can push two small masses together and when you turn it off they will be pulled together so a very nice thing for formation flights this is not yet demonstrated in the space space but we will see that soon laser brooms laser beams if you look at the earth from far away or maybe not even so far away if you look at the world a little bit closer then it looks like this the earth is surrounded by dust we have 50 years of rocket research upper rocket parts are collided are scraped we have satellites colliding that makes a lot of of dust there are about 30,000 objects in the size of 10 cm in the environment there are over 200 million of objects smaller than 1 mm these are of course the geosynchronous orbits is that a problem? yes, it is a big problem here we see a nice picture of the ESA from September 2016 Sentinel-1A is one of the new earth observation satellites of the ESA on the left side we see a solar panel on the right side after a part of the planet was hit by a planet that corresponds to a 5 mm diameter of space trash we have to think how in this case the space traffic also takes our trash an idea is to shoot from the ground of course not in a sense that you destroy these objects and get smaller objects ahead that is not what we want how can we reduce the size of these objects if we get them to an orbit that they will slowly get down so that they solve the problem that is what was suggested and if you take a commercial high power laser that you can buy and a telescope then you could change the orbit speed of the space in the size of 1 to 10 cm in the size of 1 mm per second it is like a solar sail we move the object with photons it has a somewhat changed orbit it will enter the earth atmosphere and burn of course it was also suggested to do that from the space space it is the same person who also worked in the StarShot project from Lubin and Cosmo et al in 2015 if you want to look at this paper it is a very interesting proposal that is now a satellite of a slightly deeper space move the goal is not necessarily to move only space trash but also to meet asteroids it has large solar sails to get it we find an object which is dangerous for the earth to recognize then we can find it after that you can take part in it people talk seriously and what you do is not just to move the asteroid with photons but here also frozen materials gases and you sublimate these gases and while this gas is sublimated from the inner asteroid there is also a certain shift just like a little chemical like a little chemical rocket and that actually pushes things out of the way so this so-called the star light mission so the proposal is a own laser platform with more powerful lasers and a series of mirrors to somewhere in space to, for example, turn on asteroids that may take a half day every day for a few years for a turn so that it doesn't hit us in 30 years and then you can turn it in another direction and you can push spaceships on this way and the star shot and other things that you want to push through the space that would be possible it's shown here in detail how to do this with an asteroid yes, as I said you sublimate the gases and use it as a shift so that's not what we already have in space that's a proposal laser sensing is laser sensoric laser sensing is so-called LiDAR LiDAR we do have a transmitter on a space vehicle that goes down into the atmosphere inside a pulsed laser like the laser in the last year and we talked about what happened where the laser is when you start the pulse and where it is after a certain time it goes down into the atmosphere and of course it draws different air layers and then you can look at different layers so clouds, whatever and then there's a feedback and so of course you need time when the light is connected to the bottom and the top the intensity is applied over time and that's not only with one laser but maybe with two and therefore you can use different wave lengths and you can look at what the one wave length is absorbed or absorbed by the atmosphere and do the same for the other wave lengths and then correlate and then you might even learn something about the chemical composition of the earth in our sight line or we do something like a Doppler shift where we can learn something about the wind which waves in the atmosphere so it's our timeline and something that's shown here so the distance corresponds to the altitude so the altitude and of course the anti-signal corresponds to the ground that will hopefully start next year it was a bit delayed it's a new satellite just to measure the wind on the right we can see the description the only instrument on this satellite will be the wind wave and it should give precise measurements about the wind wave and of course we use the Doppler effect where we send a signal and measure the signal shift of course you have to calculate the satellite speed and so on that's of course complicated and if we look at the instrument that looks like this in the talk before that's a lesson that we also had in the previous talk it's a technique that with satellites is a bit together we heard a different lecture about the microscope and how to build your own microscope and here we of course learned how to build it to improve the resolution how to build it on an optical bank here it's the same except that you have to start this device that's the critical part because it's incredibly complicated when you start a physicist is of course not a friend of mine comes to my lab and steps on a table that's why it's tested and tested and tested and again tested and after you've tested enough you test even more another thing you can do is distance measurement that's used on the non-transfer vehicle that's docked on the ISS on the left we see this little device and it sees the international space station in the in the distance so you know where you have to dock the white in the middle that's one of the use cups all docked the other ISS docked that's used routinely in space and maybe something you can see in your own weather every day we'll talk about that later maybe in the next lecture it's about the gravitational waves we have to communicate between different satellites that's why we have to use 3 satellites that's why we use 3 satellites that are 4,000 kilometers separated to measure the gravitational waves that's what we'll experience in the next lecture in the next lecture there's a brief overview about how our combinations of lasers in the space that's affected the first comet-cell satellites that use it will start next year why do we do that laser communication why don't we just do the normal Kao or Kuuband communication I mean satellite television that's okay of course satellites on the left have a much higher bandwidth it's very, very efficient it's actually interesting for space and that's very interesting for space use because we've learned every kilogram that we bring to space costs us a lot of money and so if you look at radiofrequency and if we look at about 0.5 megabit per second per watt if you use a laser then you could get 5 megabit per kilogram the laser communication terminals are much smaller from the antenna size if you have a satellite that looks at the earth then you have a very big communication footprint with a telescope you have about 20 centimeters so you can lower the distance radius to about 6 kilometers that means only the only one who sits in the middle of the desert can listen to you this interferometrically and then if you actually if you want to do it interferometrically and if you have to adjust the interference that doesn't work at all that's as rough as it looks what we already have that's the radio connection between a base station ground segment and this is the satellite bus that's how it's called and then the user is on top of it so a satellite bus is a satellite and the user is on top of it what you actually want to do so for example this is a geostationary orbit for satellite TV but there are other things that also fly around in geostationary orbit in orbit or in close to orbit and you see that and now we have a satellite that looks at the air for example to look at the wind and then it is only visible from your base station for a short time who of you has made the SDR software defined radio on the NOAA satellite so these people know what I'm talking about we have about 10-20 minutes if you look back and see the satellite where you can record these weather images and then nothing more it would be nice to have an optical link with high data rates also for the geostationary satellites and then maybe as a hub and then talk about these satellites with the close to orbit and the satellites there and so on so maybe also radio but as I said high data rates and all the advantages that come with lasers so for the technical interested people here how do we communicate here we have three different modulation types the on off key that means you just switch the laser off and on which you have at home and that's what you do from ground to space then we have some position modulation which happens in the remote control and well actually a small break perfect so this is what you do from so that's what you do ok that's what you do here that's what you do from ground to space and very indistinguishable by the atmosphere you just have to look through the atmosphere and if you don't have anything you can also use laser modulation principles like binary phase shift or higher modulation and that means if you want to modulate the phase you don't want to have a medium and that's what makes the atmosphere that's just for space for space to space so that's what a terminal for laser communication looks like you have the laser and all that's down there down at the bottom end we have a mirror that reflects and then we have the blind the central one about 30 centimeters and that's what it looks like from the inside 3-10 centimeters sorry the ones that bring the laser to the outside as I said different modulation schematics are used different frequencies are used typically if you want to use telecom equipment from the charging point if you want to use it again you have certain frequencies and if you want to use a certain laser infrared then you have 7-64 centimeters so here in the demonstration the NASA that communicates with the ESA station in Geneva and that's what it looks like from the world there's no video online but if you look at the communication through this optical module it's just laser but in turn you need control electronics, you need a modem but the nice thing is if you do this in a standardized way then you don't have a complicated setup like for example in the experiment for the wind measurements with the ladder that goes down here you just have to take normal telecommunications industry equipment screw together and finish and you can also use it for deep communication a proposal by NASA that can do this from satellite to Mars satellite to satellite that's what the ESA did Terrasa and N-Fire with these satellites and the Europeans are building a data transmission system EDIS Data Relay System on a commercial satellite hotel satellite and a single satellite that will be launched later and here in red the satellite laser connections and then to the ground and then we have to another vehicle and down the next step of the next step is work the so-called globe net different satellites will be positioned on geostationary runway around the earth that then communicate from satellite to satellite with laser and of course the next step and my personal interest would be to have this anything else? Yes, I think I know that in abstract I mentioned weird stuff communication laser based laser based communication from underwater boats that are underwater in the space yes, that was already done that the disadvantage is that you don't get public public publications about it that can be shown, that can be streamed can be googled after that you can really find nice information it is for certain frequencies in the blue and green area the ocean is actually quite reliable for these laser waves and you don't need something that is moving on the surface of the ocean and then kind of a glass phasor line under underwater boats, no, no just the laser through the ocean just look it up just look it up, very interesting some of these things are actually out of secret so I don't work on secret stuff and when I do, I shouldn't say yes but something is happening in the space above our heads and in the near future so just what's going on with asteroids I don't want that, next talk thanks thanks also to the listeners for this translation questions won't be given your officials are Sebalis and Johannes please give us feedback we have a Twitter account c3lingo and there is also an email hello at c3lingo.org but there is one more question it's amazing but I'm not the gentleman okay it's just about how far are the weather effects it's just about the communication about weather effects we have tried to and we noticed fog is bad snow is even worse you have these problems of course the only thing you can do is maybe use modulations that have more immunity otherwise you just don't have communication so the segment for the basic connection for example at GlobeNet EDIS the connections down there are still secured with radio connections okay it's going to be a bit too loud if you have more questions come forward ask Peter directly and please one last big applause to thank you Peter