 Welcome, everybody. Imagine you're a student and you've spent the better part of the last two semesters building your aerospace project. Now you're quite fed up with it and you need a way to get it away from you as quick as possible, as far as possible. What better than using a balloon or even a rocket? Exactly for this, there's Rexis and Bexis. And if you're wondering Who is crazy enough to travel to the high north freezing their fingers off setting it all up? Well, just talk to panic and self and Give them a warm round of applause So welcome to our talk on the Rexis and Bexis project, which is one way to get your student experiments into space Or if you're a teacher you can propose a topic for your students to do so we both are Simple students from Jena and Munich and we are not talking in the name of the Rexis and Bexis program or the organizers We just share our insights as participants in the program So basically Rexis and Bexis is your flight ticket into space for an experiment that you designed The program Rexis and Bexis is realized under a bilateral agency agreement between the German Aerospace Center DLR and the Swedish National Space Board SNSB, which is some of the counterpart the Swedish of the German DLR Furthermore the Swedish share of the payload has been made accessible to teams from ESA and also There are a lot of organizations involved in this project That support the teams and the design and development of their experiments So first for the Rexis Rexis stands for rocket experiments for university students And it's basically a cheap launch system with two launches per year these are formerly so these rocket motors are formerly military rocket surface to air rockets that are repurposed to Lift the the scientific payload instead of warheads Basically, we can or these rockets can carry up to five experiments and They are unguided rockets, so there's no active Vector thrust control for example And they are simply spin stabilized And the scientific payload masses about 30 kilograms. So as you can see there are several modules there and Basically normally there are four modules as these as these ring modules and there may be one behind or below the nose cone then there's Vexus Vexus experiments are Simple balloon experiments atmospheric research balloons you have a gondola where you can put your experiments inside these are up to six experiments per balloon and the Plastic balloon is just filled with helium and it then goes up to about 35 kilometers in hate and You have still communication during the flight with your experiments So all these launches take place from Kiruna Space Center in Northern Sweden near a town called Kiruna Just that you have a rough estimate. Well, it is so if you go there in summer it looks like this Basically, that's also one of the reasons to have the space center there. There's a lot of nothing so if the payload and the motors fall back to ground no one is hurt and So it is a safe place to be you also see in the foreground this Big pad the balloon pad That's where the balloons are launched and in the background where you have You are basically in the center of the image There's the rocket launch pad and there are multiple launches there for different rocket types Because they are of course, they are not only Rex's rocket launch launch there, but also other technology experiments So how about all the organizations involved? So this table shows Somehow a rough estimate of how these organizations work together They make bridge the borders to to other services So basically from from the beginning on there's the DLR Space administration involved and SNSP involved as basically financial Yeah, or providing the the financial capital to Just conduct the experiment and the flights and costs for travel and so on so And also in this case also either for the Swedish share They are all involved in the project management. So they basically lay out how the the project Faces are which dates to use and so on Then there comes a subcontractor, which is star which is the center of appliance space technology and microgravity in Bremen They have a drop tower facility where you can do Microgravity experiments and they are also involved in the Rex's and Bexar's program here They basically are then advising all the teams throughout their project and Are the direct Partners to talk to if there are problems The others organizations are of course still visible. So they are involved for example in the decision process Which experiment should be selected? But they are not directly involved usually in the design of the experiments Then there's still are more over which is another part of deal are namely the mobile rocket base They are responsible for doing the launch together with SSC the Swedish space cooperation SSC owns as range for example, so They are providing all the Necessary infrastructure for the launch the launch itself and the rocket motors and so on So there are a couple of phases of the project as I already mentioned So first of all the first step is the selection workshop so yeah submitted a proposal to the Rex's and Bexar's committee and They decide Whether it looks interesting what you're doing where whether it looks feasible with given time constraints or financial constraints and If your experiment gets selected there are several design reviews or reviews these are usual at the end to Or at the end of one part of the project to fulfill one milestone and they are Going with increasing granularity on just the the details as your project evolves So for example at the preliminary design review, they are usually just the rough plan still But not a final project yet and nothing tested yet so to say And so this Just goes on until the bench test for example, which is one of the tests where all the experiments are connected together and It's basically just some A couple of months before the launch campaign So I was involved in the Fox experiment. We did fiber optic vibration sensing on board such Rocket which was Rex's 15 Which was also last year in summer we were a bunch of students from the to Munich and Basically the core team were six people one PhD students for ordinary undergraduate students and one pupil So the experiment involved some some laser optics or lasers and fiber optics circuit design Software had to be written and so on so What did we want to do so? Basically, we used fiber optical sensors to do vibration sensing and a vibration sensing Means effectively measuring acceleration. So how can you use a fiber to measure something one of these possibilities? Is a so-called fiber break grating a fiber break grating is in principle a normal fiber But with the difference that it does not transmit all light from one end to the other But it has an inscribed periodic change of the refractive index So this you can see with these these dishes inside the fiber These basically Make the fiber behave in a way that one Specific wavelength that we call the the break wavelength is reflected to the input side And of course on the transmission side you see an absorption line So that alone would not allow us to measure anything But this break wavelength depends on the temperature for example So if we increase the temperature by one Kelvin we see a shift in the peak wavelength of this break wavelength by 10 picometers and the same way if you take a one meter long fiber and Expand it to by one micrometer You see also a shift in one picometer of the wavelength So this way we can for example attach a seismic mass to the fiber and if some force acts on the mass We see an extension of the fiber. So the We see a shift in the wavelength and who follow the shift in the wavelength We can calculate the acceleration on this mass So what are benefits of this technology in for space? So first of all these allowed to build quite lightweight sensor systems if you compare that for example to normal resistive strain gorgeous We don't need isolation on the cables because this is just a fiber and we don't have any interference or electromagnetic complete compatibility issues with other other electronics around also There are no sparks so we can place it quite close to propellants for example Or we could put off we could think of a fiber that we just put on the complete rocket I have also multiple sensors inside this fiber And we don't get any issues with the the present Parts that are around this so There already exists studies on Papers on how to use Fiber optics or fiber break ratings for space applications, but these are mainly Lab setups so these are not tested in flight and there are only a few examples where this was done So we thought whether it is Possible to operate such an fbd fiber break rating measurement system on the rocket and Just see how it how it turned out So these were our fiber optical sensors So the first one is the acceleration sensor this one is a sensor that we that we bought We also developed our own one, but we couldn't use it in the end So we need to use the fallback solution The overload capability is plus minus 50g which is important, but you will see later normally the rockets so there's a Rex's Manual that has several specifications on the rocket and it says that the expected maximum acceleration is about 20 or 25 g So this should be sufficient we thought Then we also have One fiber optical temperature sensor that you can see here, and there's also attached nearby the reference sensor For the accelerometer we also we also need a reference sensor Which is was a normal MEM space electrical sensor that was placed close to the fiber optical sensors and a lot of other Temperature sensors around the module So how how does such an optical system with these fiber break ratings work? So first of all we have a light source that produces a very wide band of or broadband of infrared light This was done by a normal pump laser and an erbium doped fiber So then this very broad light goes through a fiber club coupler and is split up into three beams But then go to each of our three sensors. So two accelerometers fiber optical ones and one temperature sensor So from there it goes through a 50-50 coupler and to the sensor from there The light gets reflected and goes back through the coupler and comes to a so-called interrogated chip the interrogated chip basically measures in the first path it has an edge field in front of of the light and a diode and So we can measure the photo current of the diode and we know basically that the peak wavelength of The the break rating Because also the light source might have some fluctuations in the intensity That of light that it produces we also need a reference of the total emitted light that we received So we also have one path without the edge filter to have an absolute number What was the the inputs like basically for for our sensor? So this is such Rex's rocket the rocket is about six meters long our experiment was directly under the nose cone Or below the nose cone not with not within the nose cone the nose cone was empty and Below us there were three other experiments There was for example Medusa from the University of Rostock Strauss at R2 from the University of Strauss Clyde and An experiment called Isaac from KTH Stockholm As you can see there are some some silver parts on it So these are hatches because all these three experiments had so-called free-falling units So these are ejectables that you can eject from the rocket That then fly fly down The the normal way so these are for example, they can be used to test CubeSats Which was the case for Strauss at therefore you have this 10 to 10 centimeter hatches For for Strauss at Then there's the rocket service module. That's from more of a and the recovery module. That's also from more of a so every experiment gets several Interfaces for example power for example a data downlink Provided from the service module and the data is then transmitted by the service module to the ground station and then below the recovery module There's the improved Orion motor So how did our experiment look like as you can see it is basically just this this module worth 356 millimeters in diameter and We have a power supply there and we have the light source as I said and from there the light goes to the fiber couplers through this beam splitter so you can see That there are three couplers and basically the black part below the orange fiber cables that are Yeah, rode up there Is below is the one of the one to three splitters and then we get three output signals so from each of the fiber couplers we go one or one goes to the temperature sensor and the other two go to the accelerometers and From there it goes back to the fiber couplers and one way Goes of course back to the light source But we ignore that and the other part goes to the interrogator chips from there It goes on to PCBs through several filter stages and to a microcontroller that then stores all the data on an SD card And also transmits part of it down to the ground station So that's this onboard data handling part So how does such a launch look like this is the view from the so-called science center So there are basically two locations where you can be during such a rocket launch because they are of course Safety regulations there. So one is the science center, which this recording comes from Which is about one kilometer away from the launch site and then there's the so-called radar hill which is about two or a bit more kilometers away and As you can see basically from the science center, so you don't see that much But we also had other experiments on the rocket so They also had a camera on board the rocket and we can also see the view from inside the rocket to the outside So first of all the rocket that you see there is not our rocket that is flying That was just another empty rocket that was placed there That's normally below the the tower and they just moved away the tower a bit The the sound in the end you probably noticed it Stopped so first of all you notice the spinning which is at a rate of about four hertz That's just to stabilize the rocket during the flight because as I said it is unguided then you probably noticed that we were above the clouds after about seven seconds and the other thing you noticed is the sound that Somehow probably sounded Yeah, you probably don't know where it comes from it's just the air that flows out of the modules because of the lower pressure outside So that's basically the sound that you can hear and in the end You also hear that there was This the sound disappeared. That's because there was not enough air anymore for the microphone to work And then we have a third one this is so this was done by Moraba and and So it goes so that was another rocket, but they mounted a camera on top the rocket launcher and Just see how it goes so It goes quite fast so we had Now to our results we first had the temperature measurements and you can see that there's some spike from the fiber so the first thing is Both measure measurements are quite close together. So The the sensing is correct. We can say the other thing is that we notice is that at Basically lift of time t plus zero seconds We have a spike in from the fiber optical sensor, which is basically because the fiber acts as As an accelerometer in this case because there's still a small mass attached to the fiber But still it's a mass so we can measure or we can see the acceleration inside this temperature profile the other part is that we have The acceleration from our normal sensor and the five optical sensor and we see that something Bad happens at the beginning everything seems still fine, but then at lift off something changes So what has happened So that was the the flight direction so the zed the z axis and Basically six sixty milliseconds before we get the official lift off signal That's the time between ignition and the the rocket moves basically we see a very high acceleration that exceeds our breakdown forest for the For our accelerometers the fiber optical ones and Basically the fire the the sensor Could not reset into the old position. So some parts inside were damaged and so we had an offset of minus 20g around but still There were there were some signal and we can adjust it by by rescaling and adjusting the offset of the fiber Back to the normal profile so we can see that we reached about 30g of Acceleration of course, this is outside the spec of the accelerometer. So these are not fully trustable values but that just shows that there's quite some energy at the start at least That exceeds the normally measured Acceleration values So the outcome was that on the one hand we can operate such a fiber break rating based measurement system on this rocket But on the other hand there are still some problems that need to be solved or need to be avoided in the future that have to do with Yeah issues that you normally don't see if you sample too slow that you can see these very high Excerations at the beginning. Okay, so now I will talk about the aca team We were a team of was quite a small team of five engineering students from Jena in the eastern part of Germany and The basic idea behind archer was that we wanted to build an ADSB receiver To place it for example in a satellite because in densely populated area for example at the Atlantic or so There's no really control of the aircrafts which are flying there And the idea was that we wanted to build a small receiver which can operate for example at the satellite and The goal was that we receive And these ADSB data which are transmitted from airplanes every second nearly every second during a backstop flight and Wanted to test the experiment during the flight and we choose The backstop flight because we had much more longer time where we can measure these airplanes and One other questions was we are in pretty height of 30 kilometers or so From which distance can we receive any airplanes anymore? So that's a very rough Overview of the aca experiment so we have our airplanes which are transmitting these ADSB signals every second and Then we have the aca experiment Which receives these data we are saving the data on board and then there's a e-link or so-called e-link module in the Baxus balloon and We can transmit the data back to earth and see it in the ground today Station and also save the data there. Here's another topic. We have our ADSB data which are coming from the outside and we have at the outside of our gondola we have the antenna mounted and then we have the ADSB receiver which is in our module and we have an FPGA where we do all the signal processing stuff and Decoding the frames which are coming from the airplanes and then we have a small arm computer Which saves the data and also down links the data down to earth and also we could talk to experiment and Set some command commands during the flight The electrical concept is relatively simple We have an RF receiver and the the data is sent at the frequency of around 1.1 gigahertz So we are filtering the data. We are amplific We have an amplification stage then we have a few other filters and amplifiers and Then we have a logarithmic detector and the data from the logarithmic detector directly is input in an ADC Analog to digital converter and then we are doing the signal processing stuff in the FPGA and the FPGA sends the decoded data where a serial Connection to the arm computer where we can save it and start it later and We had an Ethernet through or an Ethernet connection because this e-link is mainly Wifi connection something like that. It has a little bit more power than a wifey connection But basically it's a wifey connection We had some problems with the front end we used in the first prototype We used the so-called mini RDSP. You can take a look at the internet. It's well documented and The problem was that there was only one amplifier and it oscillates a lot so we split the amplification into two stages and then we had no problems with amplification and so on and You can see here. That's our second prototype And there are the amplification is put into two stages We built a Baseboard or so-called baseboard. We had an FPGA on Underneath it and the baseboard contains the Dairf receiver. You can see it here. You can see here the ADC the analog to digital converter and that's our arm computer, which was also developed by us and it Was stacked on top of that The board computer was developed by Hannes. He's one of our team members during his master thesis and it runs Linux and is Whatever it was designed for low power consumption. So it also fits in our concept that we wanted to build a receiver which consumes Basically nothing or not really a lot of energy And you can see here a chart where we put all together So in total we had a power consumption less than one watt. So we think that's quite okay But for example, if we would use the experiment doing a satellite flight then The Ethernet connection wouldn't be needed anymore. So the power consumption could be reduced further because The Ethernet connection consumes the most energy in the whole experiment Mechanical we built Quite a simple mechanical metal box. You can see it here in the in the left Where you have the connector connectors outside from the left There's the air connector where the antenna is mounted then we have the power connection and on the right we have the Ethernet connection and three LEDs where we could see some Indicators or some errors for example when we went to go into when the experiment was modded in the gondola Look inside of the box. It was really only this metal box and we had here our Our baseboard our arm computer and that's the air connection which which goes directly in the front and here We had an ESD a material only for isolation and terminal Terminal isolation of the do during the flight in In October last year the experiment experiment was started from S range you saw some pictures before At 1051 we reached the floating level of around 28 kilometers But we had a lot of we had a strong horizontal winds So the balloon had to be cut down at 12 o'clock The problem is that they are not allowed to fly in the Russian sector So we landed or later we landed down in Finland and it was Good luck that we landed there and that's a picture of our gondola and you can say here That was our small experiment That's the power box where the batteries are located inside and that's the so-called e-link module Which is basically a Wi-Fi connection and that was another experiment from I think Bologna and I And they do they are done some meteorological measurements in the atmosphere during the floating phase To the results and basically the experiment worked very well We could track a lot of airplanes during the flight and in total we received around 200,000 mod s messages and In total that are around 110 unique airplanes We could see and the maximum distance was around 620 kilometers, but we expected more we expected a distance from around 1,100 kilometers and The problem was that we had some dropouts with our in our air flink So we think that we had the broken antenna connection with which was mostly likely Due to a mechanical problem due to transport or so Here's a picture during the flight here. You can see that that was the airplane which Was from the highest Distance 620 kilometers around and that's here in the middle. That's Kiruna and also Kiruna airport and in blue we have the valid most mod s measured the messages we received during the flight and At this time we had the launch and The count of mod s messages Increases a lot and then we had this degradation you can see during the flight and we think that That's the reason because of the broken antenna connection So from time to time we had a lot of messages we received and then for example for two minutes the The count of messages dropped out completely or nearly completely. So we had really problems with our antenna But all in all we received a lot of Airplanes and we could say okay. The experiment is working. Well actually Terminal behavior we mounted six equal to see sensors in the experiment to monitor the temperature and At the launch pad and during the experiment when it was on the launch pad the Temperature rises and then of course we are the balloon was rising and the temperature was rising until Around that it was the outside temperature at minus 40 degree and then the gondola was moving Slowly into the Sun and then the Sun was Shining directly on our experiment. So the temperature rises again. Okay, so we made a short Time-lapse moves, sorry, I have no I have no Wheel movie of the launch and nobody in the team had a movie of the balloon Start, but we made a short time-lapse where you can see Here in the in the right the yellow card that's Haku less Haku less is the launch vehicle at S range You can see the gondola which is mounted there and The balloon is on the left Okay, during the after the flight we we played all the data we received and made a small Time-lapse movie where you can see the airplanes flying around Sweden and Norway During distance thing is for example to show you only one thing is for example You see you have here Q and I airport and you will see airplanes which are flying to Q and I land and fly again and of course you can see a lot of Airplane Roots or streets in the air Which you can be which we could track during the whole flight Okay, and if you have or if you want to build an experiment or and you want to participate in the Rexxas-Bexus program you maybe ask yourself now how could I do that and we think the first idea is that you have to get an idea and We have only written some questions down For example rusty experiments in similar kind already flown and can we improve the early experiment which was flown? some years ago or so Again and do you need external support which is critical for your experiment? For example, do you need any labs which cannot cannot be provided by the Rexxas-Bexus program? Or do we need extra finance support and so on so on and We think that it's in the first hand It's important that you find people who are motivated to work in in this project for example Bexus projects are running for around 10 or 11 months Whereas Rexxas programs are running for 12 months no 13 18 months so that's a lot of time and you have to do it or mostly all during the during your Study at university So you also need people who are motivated. That's a very important thing in the Rexxas-Bexus program And we can say from previous Rexxas-Bexus experiments Mostly the problem is that they people lost the team or left the team and The team had a lot of problems with the workload which has to be done until the launch campaign So the next possibility to write a call for proposal or to write a paper for the selection workshop opens in summer 2016 and for German students you should you must not but you should write a letter of intent until the beginning of August next year and for European students they should register at either education project database and Write down that they want to participate in the program and for details. You should see at rexxas-bexus.net Because there's everything listed and you can read it later Okay, some acknowledgments We have the first team that were the team members of the first team ARCA We were this team Thanks to the guys who brought us these images and so on And the videos you saw for example from the rexxas rocket We're from the Isaac experiment and from the alarm over and if you read if you want to read a little bit more we have Some web pages written down and if you have questions or so talk to us later or what as an email Do we have some time left? five minutes 15 Yeah Okay, so we can show just a few images from the campaign And then we do a Q&A. So this is the the team photo of the Rexas 15 and 16 teams that were that were there So you see these are quite a lot of people involved and these are we're only the people that were sent to the launch campaign There may be or there are even more people involved in the project itself This is again the photo, but for back says 18 and 19 So again a lot of people Maybe we can we can open for Q&A now. Thank you very much for this time If you have any questions, please line up at the four microphones we have here and while you're doing this Off to the signal angel relaying a question from IRC We currently have a question Regarding funding and regarding the costs involved with launches. Can you? Maybe elaborate a bit on the costs for launching with Rexas or Bexos maybe as cost per kilogram or so and The total funding for such a launch. So I don't know the total funding, but the launch itself is free So that's paid by the Rexas Bexos. So that's free for the teams basically what the teams have to pay Or no, the teams also get some money for example to build the modules and some specific parts That are built for example by Zarm or by other companies where you just buy these things and everything that Exceeds that amount. I don't have an exact figure a couple of thousand euros That then has to be paid by your own or you have to develop it by your own or you need a lap of your university Or some some machines of your university. So they can can just see Yeah, where you can Get other support or other sponsors for these parts a Question from the front right microphone Okay Okay Hello, I have a question regarding the fiber optic measurements you did Because you explain that it has some advantages. For example that it can be built very light-white. Now my question is did your experiments Had or do you hope that your experiment will have some effect on the development of these Measurement systems for actual emissions from NASA or the DLR for example Some kind of fiber optic measurements being done on ISS So what what lies in the future? So I don't know of any specific plans or things but So we see that there are some problems with the fiber optics, but in total due to the Due to that that you don't need no Isolation from the of the fibers compared to electrical cables so that There there might be some Some programs, but nothing specific that they know of can I ask a follow-up question this short one Can you give a rough estimate on how much weight you can save in comparison to The models used currently for measurements Not by heart. Sorry. Okay. Thank you Front left microphone Hi, thanks for the talk. I'm interested in some numbers for both Rex's and Bex's What's the kind of flight duration you can achieve and what about the maximum altitude? Yes, so the altitude I think we had that on the on the slide is for the Rex's rockets about 80 or 70 to 90 kilometers, so it depends of course on the mass of the rocket and Usually you try to get all the experiments that started for this rocket also on the rocket that you don't have to fly an empty experiment So therefore you probably just take away some of the hate and just and take the the heavier Experiment but so our flight because all our modules were quite heavy. Our flight was only up to 18 80.7 kilometers But the our sister flight rex 16 was to 86 or 87 kilometers a Question from our signal angel on IRC somebody wanted to know what happens to the rocket when it Reaches its High point the highest altitude does it come back? Can yes some parts be reused things like that Yes, so the 80 kilometers are not sufficient to get the experiments into orbit So basically everything falls down again There will be or usually there's a motor separation So the motor falls down before the payload and then sometime later the payload comes down again this is so that the payload falls back on on a parachute and you can see that here How it looks like after these couple of slides. So that's just the payload without the The motor that's how it is mounted on the on the launcher And that's basically how it How how rex is 15 came back front left microphone? I think you missed some of my question I also wanted to know about the flight duration of rex's and pexus as well so the rex's flight this are three minutes up and then probably about I Think eight minutes or so down But most of the time is on the parachute. So there's nothing special any more happening Bexos is a little bit complicated to say So for example all on our flight was only about in two hours or so But for example one of the last Bexos flight which fly this year in October this year That a very long flight because there were no Horizontal winds so and there are pictures where the balloon was launched two hours ago and they could Take a photo from the launch pad Where the balloon was visible in 30 kilometers height? So it could be quite long and it depends on the horizontal winds for example and also on the constraints of the experiments some experiments wants to want to have a long duration of measurement and some experiment want to have a slower duration of flight law of Floating because for example, they only want to take measurements in the rising and falling of the balloon Are there any more questions? It does not look like that. So please give a warm round of applause to panic themselves