Day 2 in DLR Bremen…..Time event simulation

Written by Monica

Today has been a very exciting day, all the experiments in the Rexus 10 (GAGa, FOCUS,M-BEAM and SQUID) were connected together and we simulate the time event, our SQUID communication with the rocket service module is as we expected,for now we just run with  the test mode, i.e. we control everything that happens in the experiment, but tomorrow after a vibration test we will run the mission mode, where the functions should perform automatically.

Of course, watching the experiment working feels very  nice, but it also has represented long days and an incredible amount of work, everything is  small scale and every single screw has its own way to be put.

Right now, the time is devoted to prepare the rope that goes into the cutter that will release parachute… once it is done we can then pack the parachute into the FreeFlightUnit … for 2nd time today 😉

Tomorrow..vibration test..and right after …test ejection of the booms…Lets hope everything works !!!!

Arriving in Bremen

So after a very busy and chaotic night it was time to leave for Germany and DLR in Bremen. We had decided to drive here and we had to leave on saturday if we were going to make it. The plan was to finish all the packing friday night and leave early saturday morning… However, it did’t go exactly like planed on friday, as you may have read. So at 1.30am we decided I wold go home to sleep so we could have one driver who had gotten some hours of sleep. It proved to be a good decision since the others got no, or almost no sleep that night. But we managed to pack almost everything and get going after lunch on saturday.


We drove down to Helsingborg, where we spent the night at Gustav’s grand parents. They were really nice having food ready for us when we arrived. Sunday we spent in the car  driving from Sweden, through Denmark and finally arriving in Bremen, Germany. We was quite tired by that time but managed to find our hotel, members of one of the other teams (M-beam) and our contact from DLR and ESA. After a nice dinner and some beers, we are after all in Germany, we went to bed sleeping like logs.
Yesterday: Monday morning. Still the same tasks but another lab in another country. Continue the work we did not manage to get done before leaving SPP. This means fitting the batteries and mounting all the boards in the E-box. So far we have managed to fit it all almost together and breaking about five screws doing so. It feels a little bit taking three steps forwards and two back, but slowly we where getting there.
So finally, at about six, we had goth all the parts together and everything seemed to work fine. First we tried to connect directly to the eBox it self to make sure that we could communicate to it which worked fine but then when we had assembled the complete FFU and placed it on the RMU we where not able to communicate with the experiment through the umbilical. So we started to try to find the problem and we soon realized that the signal pins needs to go further in to the experiment in order to get the signals through. To solve this we re soldered the pins and then everything went fine. So after some long hours we succeeded with the communication which made it possible to proceed with the Electrical interface test which went perfect. This continued with a test together with the M-beam team, which are placed below us in the nosecone. This also went fine and we finally could round of for the day, which where about time since the clock where closing 9 pm fast.

 

We rounded of the evening together with some of the other teams and some of the ESA, DLR and SSC personnel at a restaurant in town.

Ejection testing night

As everyone probably has noted the delivery is really closing in so yesterday we decided on trying to do three different tests, all of them with ejection system as a common dominator. First of was the top plate ejection system test. This system has been the focus for a server amount of testing. The system is important since it covers the parachute, when activated the parachute is exposed to the surrounding air. This time the focus was how the dynema rope moved. The test was successful and ca be seen in the following video.

 

 

Next up was the spring ejection test. This test have been performed earlier but the big difference this time was the use of the distance ring which enables another cm of tensioning. It also secures that the spring gets pressed down in the gully fully. The video covering the ejection can be seen below.

 

 

Last of during the night was the long term ejection spring test. The idea is to ensure that the system does not lose tension during a longer period of time. This also means that we won’t have access to the system until next monday when we also will perform a new ejection test to ensure that we get the same ejection force after that the spring have been compressed during a longer period of time.

 

A brief look into the ongoing work

After a weekend of well deserved rest this week has been crazy as always. As you all know we’re really trying our best to get things ready ahead of delivery. Therefore the blog has been a bit low prioritized but to at least give something I´ll add some pictures from the last preparations ahead of the real EAR last week.

 

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 😛

Disaster strikes…

Last night actually became a sad story. After all testing and working during last night everything turned out to a small disaster. So what happened really, well we’e not yet entirely sure but I’ll tell you what we observed. Last thing on the task list last night was to mount all hardware in their specified places. Due to that we had been using the eBox (the rectangular middle aluminum box where all the electronic boards are mounted) for some time it had not yet been modified to hold the ovenCutter. This meant that we had to move all the boards to a new eBox. Somewhere here something went wrong cause when everything had been mounted and we tested the communication with the experiment, suddenly magic white SMOKE started to rise out of the eBox. We’re not sure what had really happened but our theory is that during the mounting (which took place at midnight last night) somethng most have been short circuited. This lead to that the MOSFET which is used to switch of the batteries started to boil.

Burned MOSFET

Suddenly white smoke started to rise from the MOSFET

Due to this small disaster we where forced to postpone the EAR until friday. So please wish us better luck for that time.

Ground support software

So the time has come to give a brief story about the ground support software (GSS). So what is the GSS? Well, actually it is quite simple to explain. The software used by the SQUID project can be divided into two different main categories. First the software which is loaded on to the probe it self and secondly the software used to monitor and communicate with the probe as well as post flight data analyzes.

The software used in the probe is written in VHDL and will be covered in a separate blog post. In general however one can say that this software controls almost everything that happens on the FFU during the mission. It also logs all sample data from the different sensors onboard the probe.

The GSS consists out of two totally different softwares,readOut and liveCom. The readOut is a Matlab script which reads out the memory data and displays it in form of plots. The tricky thing is to construct a fast script since data is stored in a rate of 2000 Hz while in flight which means that even short tests performed on the probe results in large amounts of data.

 

A example of how the data can be displayed by the plots genereated from the readOut. In this case it´s the data from the gyros in the eBox.

The liveCom in turn is pretty well explained by its name. The software is run by a computer which druing tests is connected by an old fashioned serial interface with the eBox. While in flight the connection will be wireless and go through the REXUS rockets service module. The software is written in python and makes use of the Tkinter TCL graphical interface. This combination enables the software to be run on a variety of platforms since most platforms supporting Python also suports Tkinter. The software mainly visualizes the low data rate output (LDRO) from the probe but also features a simple interface for controlling the probe which is used during system tests. However the main idea is to provide a fast way to follow the probe during the mission while it´s still in the rocket.

 

A screenshot from the liveCom software

The first launches of SQUID: Spring and RID testing

Yesterday the rocket interface disc, RID, finally arrived. This is the piece that actually mounts the free-flying unit, FFU, to the rocket. The custom made wave spring that will eject the FFU arrived a couple of weeks ago, and now we could finally mate them together.

The rocket interface disc (RID) with the ejection spring

However it soon became apparent that the spring had a tighter fit in the spring gully than we had expected, and to determine whether this would affect the ejection or not me and Mikko carried out some spring testing.

Soon half of the team had gathered around to watch and help out as we covered a sturdy table down in the workshop with foam and devised a clever way of holding the bottom plate of the FFU down against the spring. An unlucky Mario was selected sit under the table and cut a rope going down through a hole in the bottom plate and rid, and down through the table where it was hooked up to a tightening mechanism. To document the ejection we borrowed a Casio high-speed camera from the department of mechanics.

We did two “launches” today, and while the launches weren’t as straight as they could have been the results seem positive, especially since the weighted-down bottom plate was not perfectly balanced. However, since the radius of the spring is slightly lower than expected the very top part of it easily gets jammed between the bottom plate of the FFU and the RID. More testing will be done soon, but until then enjoy the fancy high-speed videos! Sorry for not having turned them right way up, but this would decrease the video quality.

The flickering is due to the flourescent lighting in the room,  and the towel in the first video was an attempt at catching the falling plate. 🙂

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.

 

Parachute load test with an unexpected outcome

Last Thursday it was time to determine once and for all how much the parachutes we use in the landing system could handle. Having failed to break them in both the car towing test and the actual drop test, me and our supervisor Gunnar Tibert resorted to more brutal methods.

One of the 70″ parachutes was hung upside down from a hook in the Structures Lab at KTH, supported by a single line of paracord which was to brake the fall. This is the same type of cord that was successfully used in the drop tests above Esrange. The parachute was loaded with about 19 kg of extra load, and dropped with 1.5 m of slack paracord.

Sometimes it's best to use what you have closest at hand! 19 kg of old newspapers have just the right density to fill out the parachute nicely.

Much to our surprise, it turned out the paracord, which we thought was rated to the equivalent of a couple of hundred kilograms in force, was the weakest link:

View from the hook of the crane, filmed with the GoPro HD Hero.

420 FPS high speed footage shot using a Casio consumer camera. This doesn’t show the paracord breaking, but is cool nontheless!

Right now we’re trying to determine the speed right before and after the line broke so we can calculate the force in the cord. At any rate, it is likely we will switch this cord for the real system to be sure that the same won’t happen during our flight! However, the cord still needs to be flexible so the shock to the experiment isn’t too great.