The next steps are to finish integrating all the software for a full system software test, finish the thermal insulation and keep on testing the infrasound sensors to get some test data to analyse! So far so good for the EXIST team, and with only 32 days until the launch campaign everyone it's all hands on deck!
Vince Still, Head of Mechanical Department
Sending scientific instruments into the Earths stratosphere requires some form of enclosure to be designed, built and tested to survive the incredibly harsh climate. In order to achieve this in the most efficient way possible, CAD software is used to design a computer model, where everything can be virtually assembled to find the optimum positioning.
This model takes a lot of time and effort to create
and refine, however just creating a model is simply
not enough! It is also difficult to manufacture and
assemble the model into the finished product.
After a lot of effort, the model was completed
and manufactured at a very affordable price.
Finally, we could see how our computer models
could finally be made into something real! This
was down to the amazing help and expertise we
received from two incredible Swedish companies
NSR (Norrköpings Svets & Reparation
AB) and Progatec AB.
NSR first helped our project by carefully advising on the grade of metals we could use. Choice of materials and material grades can be a very tricky part of any mechanical construction, where materials need the right properties in order to fulfil the given specifications. The second way they helped was creating the templates required for manufacturing. This was achieved by a combination of cutting, surface polishing and overall preparation for the manufacturing process to come.
The manufacturing was then completed by another company, Progatec AB, due to their possession of high tolerance CNC machines and willingness to engage in our student project. Manufacturing is, in short, manipulating stock materials (in our case aluminium and steel) to fit the required model. Some manufacturing examples can include bending, cutting or welding. Progatec AB created our mechanical components from the templates and materials sent by NSR, and took advantage of exciting (expensive!) machinery such as as a waterjet cutter, plate bender and a TIG welder.
We have learned an incredible deal about working with external companies, knowledge that will certainly be a huge help in the future for not only our project, but also our professional lives.
We would like to thank these companies for their huge contribution and ongoing support in our project, without which we wouldn’t have been as far as we are now!
Vacuum chamber test
The first purpose of testing our experiment in a vacuum (a vacuum is where the pressure is as close to 0 as possible, to replicate outer space!) is to see how the materials used in the experiment react in this environment. A common problem that occurs is that there is trapped moisture or air bubbles beneath the surface of the material that rises to the surface and damages the material.
The other purpose was another form of thermal test, and was to test the box at steady-state. Because the box was in the vacuum chamber for several hours, and all our electronics were switched on, the heat generated from these components cannot radiate or convect away. This means that in the vacuum environment the internals of our box will heat up. We waited for about 3 and a half hours, after which the temperature on board our Arduino Due reached a temperature of 62°C. On the bottom side of our box, our other thermometer positioned on our PCB reached a temperature of 35°C. These temperatures were well within the operational temperatures of our box so all was good! For detailed graphs of the two on-board thermometers during the vacuum test, please see below.
The Atmospheric Science Group (AGS) at Luleå University of Technology (LTU) has written an article regarding the two newly accepted LTU BEXUS projects, EXIST and IRIS.
The IRIS project is a group of close friends to the EXIST group, and we will be sharing work spaces with them during the whole BEXUS project timeline.
For more information about IRIS, visit their webpage http://www.bexusiris.com/
and follow them on facebook
The launch campaign has finally started, and the team is now settled at Esrange Space Center. We are all very happy to also welcome back Yamamoto Masayuki, and his student Hiroaki Fujitsu to Kiruna. They spend the days at Esrange together with the team, supporting and helping us out as we are getting closer to the launch. As can be seen below we all got personal tags which will allow us to enter Esrange Space Center.
The first two days of the campaign have been about assembling everything and doing individual testing. This is mostly to make sure the experiment works after the long shipment that most teams have had. Luckily for us does the Esrange Space Center lies just 40 minutes away from our university. All the different teams from all over Europe got to setup and test their experiment in a large bulding called the Dome which can be seen below.
So far, everything looks great and works as expected.
A picture showing one of the sensor boxes.
Another picture inside the Dome.
We hope to get nice results from the upcoming gondola interface test on Monday, bringing us one step closer to the flight. Another interesting test that is about to take place is us eavesdropping on our next door team DREX. Their deployable antenna may produce infrasound, and to make sure, we will record data during one of their deployments.
Lucas lowering the sensor box into the freezer.
This test was where one of the sensor boxes was put inside an industrial freezer which can reach temperatures of -86 °C! We set the temperature for -50°C as this will be the lowest temperature reached during the ascent phase of launch. The sensor box was lowered down into the chamber, with full insulation on it and a cable feed through to monitor the heaters inside our box. We waited for approximately 3 hours so everything could cool down enough to reach a steady-state. After this time, and with our heaters switched on, our Arduino Due (our on board computer) reached a temperature of 20°C and our custom build PCB reached a temperature of -7°C. Pretty cold, but everything was still working, so a success for EXIST. For detailed graphs of the two on-board thermometers during the freezer test, please see below.
Today we recieved news that EXIST has been selected to participate in BEXUS cycle 10, and will fly on BEXUS 24! So we are now entering into a year-long project, that will let us take our idea and make it real.
The next big milestone now is the Preliminary Design Review, a first version of our Student Experiment Documentation that is due 27th of January. So as not to fall behind on the work neccesary, had already began working towards the PDR, so now we can continue our work with renewed energy.
Christmas break is coming up, and hopefully there will be some time to relax in between all the work. Maybe.
Our lovely sensor box in a vacuum chamber in a pressure of roughly 15hPa (roughly 1000 times less than we are experiencing right now!)
Esrange Space Centre Tests
Freezer and Vacuum tests at Esrange Space Centre
Last week the EXIST team had the lucky experience to be able to go to Esrange Space Centre and use their vacuum chamber and freezer to test their experiment. Overall everything went exceptionally well and the test sensor box survived both the extreme negative temperature of the freezer at -50 °C, and the heat of the thermal test when in the vacuum chamber.
Firstly we arrived at roughly 7:30 in the morning on had to wait until 9:15 to get our guest passes! Here we are in the visitor's centre with our sister team IRIS while we were waiting... At least Sarah wasn't too tired to smile :).
As of the beginning of the summer
we received the infrasound
detecting instruments for our
experiment. These instruments,
namely four special made
microphone arrays from Japan,
and a low frequency pressure
transducer from Digiquartz,
have arrived here thanks to the
Professor Yamamoto at
Kochi University of Technology.
We express our greatest gratitude to the excellent international cooperation between the Professor and ourselves which has been vital for this experiment! On the third of August a REXUS/BEXUS organizer and official will visit us in Kiruna to review our experiment progress. Wish us luck!
Photo shows one of the microphone arrays (bottom), the prototype versions of our own four electronic circuit boards (center), the GPS navigation device (upper left), and also our brain-box mini-computer Arduino Due (upper right). These instruments and circuits are just some of the instruments on board our experiment to, which in turn is positioned on board the stratospheric balloon BEXUS24, to fly in October!
The EXIST experiment integration has gone tremendously well. After first constructing a test sensor box to show the REXUS/BEXUS experts during our integration progress review, we completed the flight ready sensor boxes in addition to the first test box. The insulation is manufactured and the internal wiring is finished. In our project room we have set up an attachment environment similar to the one on the BEXUS 24 flight train. We have therefore hung the sensor box with insulation up on a simulated flight train as seen below.
As though that wasn't enough excitement, our very respectable supervisor Professor Yamamoto of Kochi University of Technology has come to visit us from Japan for five days. He is very happy to see how far we have come and how well we have integrated his microphone arrays and high-end pressure transducer into our experiment as the primary instruments. During his stay we will conduct a full system infrasound test for further calibration under Yamamoto's supervision and expertise.
By next week we will be doing a full system vacuum test, as well as a full system thermal test, cooling the sensor box down to a minimum temperature of -70°C. And we thought Kiruna was cold, brr!
Preparing for Experiment Acceptance Review
The mornings in Kiruna are filled with frost and everyone can feel that winter is coming. Since the snow hasn’t actually come yet the evenings are very dark, feels a bit depressing when you are going home from the University. Project IRIS (https://www.bexusiris.com/) has the easiest solution though, just don’t go home. Jokes aside the launch is closing in and we are all a bit nervous. What if something doesn’t work? What if something breaks? Lots of “what if” ‘s but all of us have an underlying trust in our own work and that the experiment will succeed. Imagine the relief and happiness that will fill our bodies afterwards! Even if nothing works we have learned so much from this project when we look back.
For most of us in EXIST this is the last semester together as a class. Four and a half years, spending almost every day more or less together and helping each other with labs, tests and life in general. Lots of long study nights and crazy parties. Before we get too sentimental we have to remember that we are not there yet. We still haven’t launched and we still have three months of school to finish so let’s focus on that first and foremost.
The experiment is as good as complete and as you maybe have read in the earlier posts we have done a lot of tests. Even though everything works, the tests will probably continue all the way up until launch. Our latest test was to try our prototype of an anemometer cover, that’s supposed to protect the outer diode from the sunlight, but not affect the wind blowing on it too much. A tricky challenge where we have to balance the risk of sunlight hitting it and coverage from the wind.
If this design is good enough or if we change it up we will see after some more testing. And maybe even tell you about it next week. So until next time, farewell.
Lucas Svensson from the electrical team
This picture shows the vastness of the balloon workshop where our testing was done, and Robert busy in the Skype call with Dr Bowman.
Science meeting with Bowman
During the time the technical teams were busy testing our sensor boxes, our great manager Robert was busy on a Skype call with Dr Daniel Bowman, the man who gave us the idea to measure infrasound in the stratosphere over a year ago! With them in the call was our science department Sandra and Kasper, and they took the opportunity to ask many questions to Dr Bowman regarding the data analysis post the launch of the BEXUS balloon.
The team submitted the third version out of five Student Experiment Documentation (SED)s. This document is the living document of our
experiment that is constantly being updated with
the latest design, manufacturing or test plans.
This version of the document is associated with a
review that will occur on the 3rd of August. An
SSC expert and organizer from the REXUS/BEXUS
panel will come all the way up north to Kiruna and
visit the EXIST team to see how far we have come
in regarding integration of our different subsystems (Electrical, thermal, mechanical, software...). We are very excited and are therefore working hard to build our experiment!
The software design of the EXIST experiment have now been completed. Does this mean that the software team can take it easy now? Unfortunately not. Now the different parts of the software has to be integrated and then tested before we dare to fly it.
Lucas positioning our sensor box in the vacuum chamber.
Preparing for Experiment Acceptance Review
Preparations for Experimental acceptance review and tests
The last phase of the EXIST project before launch is almost complete. The EAR (experimental acceptance review) version of the SED (student experiment documentation) is finished and some final, minor changes were applied during the last day of the deadline. These changes were mostly minor tweaks to the plans during the launch campaign and procedures for the final setup of the experiment when at the launch-pad.
The launch is currently scheduled at some day between the 16th-22nd of October and the launch preparations will take place at Esrange from the 13th-15th of October. The EXIST team is very excited, HAPPINESS!
Currently, all the components of the experiment are integrated together with most of the cables which will connect our experiment to the mainframe of the BEXUS system. The total length of these cables is 120m, so quite a lot of cabling. See picture below. Because the cables came in lengths of 30m and 15m we needed to manually splice them together to achieve the lengths needed for the experiment.
Cabling of the EXIST experiment where the black cable is the Ethernet Cable and the red ones are power cables.
The electrical and software divisions are spending even more time together making sure that everything in the sensor box is functioning. Lately they have been working on the microphone arrays, since we have recently added a voltage divider and also low pass filter for sample rate reduction and anti-aliasing.
Lucas and Max are doing some software/electrical tests of the microphone array.
In order to do these tests and create some infrasound, you can imagine how many times doors have been slammed and many hands have been clapping.
Here is a photo of David getting ready for some tin inhalations.
Also, full-system testing has been performed throughout the week with positive results and the EXIST team almost have a fully functional and flight ready experiment.
The picture shows the setup of the full-system test with our software “Wizard” Max Nilsson contemplating the results. The box closest to the camera is one of the sensor boxes without its full insulation that will be situated in between the gondola and the balloon.
The full-system testing means that the 2 sensor boxes (the boxes where all the sensors and equipment are) have been connected to the relay box (the box where the power distribution, and network linking through an Ethernet switch takes place) which then has been connected to a computer through another Ethernet switch which acts as our ground station.
The picture shows a close-up of the Relay-box without insulation that will be situated on the gondola.
Apart from this, we have been trying to analyze the data, from the anemometer, that we gathered from the thermal-vacuum tests at Esrange. This will help us to calibrate it correctly to achieve a good range of output voltages without causing any damage to the electrical system. This anemometer has two diodes, one is exposed to air and the other is isolated. So depending on how hot/cold the outer diode gets, current will flow differently through the outer diode and this, together with the isolated diode, creates a voltage difference. This voltage will help us detect wind during flight.
This is how the output voltage looked like during the freezer test at Esrange. As you can see, the output voltage level higher in the freezer with a temperature of about -50 degrees Celsius compared to room temperature. The spike that you see at the end of the freezer test is caused by blowing on the cold, outer diode.
See y’all at Esrange in 16 days BYEEEH
David Skånberg and Sarah Zayouna from the thermal and electrical team