First SQUID post flight data analysis

After the successful launch and recovery of the SQUID experiment there is still a huge amount of things to do. The experiment recorded a lot of data from the different sensors (gyros, accelerometers, magnetometers etc.) and now we have to analyze the data in order to understand how the system behaved. One of the interesting sensors onboard the FFU were the gyros, that give the angular rate on the three axis. During the deployment of the wire booms, due to the increase of the moment of inertia of the FFU, the spin rate (or angular rate along the z axis) would decrease, so by looking at the recorded data from the gyros we could have a good idea of how the wire booms have behaved, which is specially important as the FFU was lost from the field of view of the camera very soon.

From the gyro data (see figure) one can clearly see the slow down of the spin rate just after ejection along the z axis, while the angular rate along the x and y axis is very close to zero, meaning that the ejection was almost perfect. What one can see on the slow down period is that there is a sudden change of the slope of the spin rate curve. By comparing this curve to a dynamical model of the system we could see that the reason for this seems to be that one of the wire booms failed after deploying around 30 cm. This was of course not good, but it didnt have a big impact on the overall performance of the FFU as it keept on spinning stably.

At the end of the slow down sequence one can see that the curve becomes flat, which means that the other three of the spheres stopped deploying (as it was expected) and the FFU kept on spinning with the wire booms deployed. After this, the retraction sequence starts, and again one can see a slight slope change of the curve, which means that a second SCALE system failed during retraction. The objective of retracting the wire booms was only for preventing them to entangle with the parachute, but luckily this did not happen and therefore it was not a major failure on the system.

One can also see another interesting event on the plot. At the end of the retraction phase, the spin rate of the FFU should be very similar to the initial one, but as one can see this did not happen, as it seems that the spin rate is decreasing (as expected due to the decrease of the moment of inertia of the FFU), but then suddenly it starts spinning up again, and becomes unstable (one can see that the data from the gyros on the x and y axis starts becoming messy). It seems that this was because the FFU started “feeling” the atmosphere before expected. One of the curves is the dynamic pressure, which was derived from the data recorded by the Rexus service module, and as one can see, at the moment on which the FFU becomes unstable, the dynamic pressure starts increasing, meaning that aerodynamic effects start being noticeable.

There is still a huge amount of data to analyze carefully, so this task will keep us busy the next months. We will keep you informed about our progress!

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First post flight analysis

After the successful launch of Rexus 10 we still have a lot of things to do. There is a lot of data stored on the FFU which will have to be analyzed in order to fully understand how the system has behaved and recover the scientific data gathered by the experiment. This data is stored in the memory inside the e-box and has not yet been extracted as the FFU was wet after landing in the snow, and as water and electronics dont like each other we decided to leave it drying.

But probably you have already seen the video we posted yesterday. The images are impressive, but the main objective of mounting the camera was to film the FFU in order to be able to check how the spheres were deployed. Unfortunately the experiment module was coning (it had a quite high precession angle) and the FFU was lost from the field of view of the camera after a few seconds. However, if one analyzes the movie carefully can extract some useful information. On the pictures you can see some snapshots taken from the camera shortly after ejection, when the FFU was still in the field of view. Of one checks the pictures from 2 to 7 can see the doors of the SCALE systems popping out gradually (all four of them) which means that the SCALE systems were in fact working, as the doors can only be released if the motor of the wire boom systems are working.

The FFU also appears later on in the video. It was however very far from the experiment module and details can hardly be identified. One can see it in the last pictures, on the bottom half of the photos close to the edge of the ejection spring (dont get confused by the brilliant thing appearing on the top of the photos, which is the nose cone of the rocket). We were unlucky enough to have the sun very close to the area on which the FFU was flying, so on the photos it usually appears as a shiny thing close to the spring. There is however a very interesting photo. If one checks the very last picture, one can see the FFU body very close to the edge of the spring and what seems to be two of the spheres close to it.

We do know that at least two of the spheres were deployed, as when we recovered the FFU two of the cables had been damaged during reentry, probably because the motors driving the wire boom systems could not overcome the centrifugal force during retraction and stalled, leaving the spheres on the free airstream, which ripped them off the cable. We will not know surely how they worked until we really process the data, specially from the sensor wheels on the SCALE systems and of the gyros and accelerometers of the FFU, but so far so good.

Mario

48 hours to go until departure

It is now just over 48 hours until we finally will leave on out journey from Stockholm to ESRANGE. We’re still working on our experiment and even if we are getting closer to completing it we still struggle with issues. One examples from the electronics is the sensors in the spheres. Due to problems with miss interpretation of the clock signal  in the spheres we have huge problems with getting the signal from them to the main board where it is supposed to be recorded. Even if we have done some great efforts and been awarded with good progress we’re now at such a late stage that we’ve had to confess that we won´t be able to fly with the sensors in the spheres. This means that we won´t be able to record the dynamics of the individual spheres. Another problem which have raised is the satellite modem. Even if we tested the system as early as during last summer it suddenly have stopped working. What seems to be the problem is that the modem module which is soldered at the flight board isn’t working. We´re now working in replacing it but it has proven to be a challenging task. However we won´t give up just yet.

Another thing we´re still working on is to get a reliable deployment of all four spheres, I´m attaching some pictures of our tries. at this moment we have at least three SCALES which deploys reliable but we have problems with the fourth one.

Last week of preparations ahead of launch campaign

So today is the second day of the last week ahead of the launch campaign. We’re all very excited and are all doing our very best in order to prepare the experiment. So what does “Prepare the experiment” this actually mean? In our project this mean that we first disassemble most of the experiment, checks the parts and then screws everything back together using new screws and Loctite. However before we start with any of these tasks we´re of course finishing off old tasks as well. Mainly this have to do with tests which we did not have time with earlier. These tests includes a variety of functionality’s, like for example the activation of the bacon transmitter which we use to recover the experiment, and of course the SCALE systems . During the remaining part of the week I hope that there will be plenty of events worth mentioning here,but for now this short post will have to do. I´ll attach some pictures from the last days as well. However I have one exciting thing to tell you about, during last week the situation in our work room / lab became impossible. Therefore I decided to use a couple of hours to change the room. We added a couple of tables, some bookshelves and also some nice working lights. You can see the newly shaped room in the photos I attached. As a continuation of this work we also went through the parts inventory and we now hope we´ve managed to sort out how many parts we have and where they are for the moment.

Screws and Logistics

Alongside all the manufacturing and testing we have to sort out things like ordering standard components, like screws. It was easier said than done to get a hold of screws for this project. The small size, specific material and low number made it harder to get a hold of. So we got some help from the staff here to find a company that could deliver all of this. When we talked to the suppliers here in Sweden they told us they only deliver orders by the pallet and so we had to go elsewhere. In the end we had to order from Switzerland. However, they were nice and fast in the delivery so in less than a week we had our longed for screws. It ends up being about 30 variations and about 100 to 400 of each so to manage this we decided to keep it well organized. See some pictures below.

SQUID PASSED EAR!!! (Hurray :D)

The battle is won but the war is not yet over.

Today SQUID had it’s EAR (Experiment Acceptance Review) which is the last review before delivery. We pushed through limited time, stressfull days, missing components, late workshop evenings, burning electronic boards, short circuited batteries, system failures, moodswings etc. and finally got through the EAR with positive results.

Mikael Inga was visiting us from the Swedish Space Corporation to carry out the EAR and most of the team was present to discuss and demonstrate the experiments current functionality. The day started of at 9:30 in the morning with a check through what has been done on earlier comments recieved from REXUS and what tests we have performed since last IPR.  Just before lunch we started of by demonstrating the functionality and workings of the experiment interface electronics and after lunch followed a more thorough experiment functionality demonstration in which we let the system run through parts of the intended operational phases finally leading to the moment of thruth, the decision. SQUID has passed EAR but as always there are comments and things to care about but nothing came up that we weren’t already aware of.

Next up is delivery and the team will now take the weekend off to recuperate from the last two weeks of battle because on monday we need to pick up the pace even further. Systems have to be fully tested, fligh boards assembled to the ebox and tested, assembly of a second FFU has to start and everyone should be happy and prepared for hard work (at least us slaves have to be) otherwise the big boss will come after us with his grand master-whip which he talks so much about nowadays 😛

The SCALE system is spinning

During the past week we’ve finally done some real progress on the SCALE system . For those of you who are not totally up to date with that the SCALE system is please check out these posts. To make a long story short, the SCALE system is probably the most central part of the whole experiment, it’s a complex mechanical structure which has one task, to deploy and retract the spherical probes which are used to make the measurements of the electromagnetic field. Due to the drastic changes we had to perform on the landing system the SCALE system where somewhat overseen and tasks which should had been performed much earlier during the project still remained when the team gathered after the summer. However due to great efforts performed by mainly Malin and Mario the system is now finally running and we now focus on optimizing the functionality of it. Below are two videos which displays the system and how it works.