Thesis Deadline // MUSCAT at Esrange

First and foremost, I want to thank all of the people involved in ISAAC, with special thanks to our bachelor thesis supervisor, Dr. Nickolay Ivchenko and the ISAAC team leader, Georg Balmer. The thesis deadline was today at 12:00, so now there is no looking back.

Our fellow “rocket heads” at MUSCAT has left Stockholm in order to go to Esrange in Kiruna. This is the place where their rocket will be launched from, and following their blog, being able to see another set of people get to do what we have been working so hard for is  very pleasing. Even our project feels more real now.

As for now MUSCAT have been going through some safety regulations of the rocket base and setting up the last test prior to launch.

We wish the whole MUSCAT team a successful experiment and a few beautiful days in the north of Sweden!

For more information on the MUSCAT experiment, please visit: http://muscatexperiment.wordpress.com/

Respectfully, Johan Jansson

Electronics are funny!

Hej!

Today after thinking it a while I have decided not to talk about the ISAAC project, but about some funny we found together. Few days ago Victoria and Johan started an intensive testing campaign with the IR source and during a break, and idea come up, electronics are funny!
Everything started long time ago, chatting about everything in which the mechanical members started to talk about how much funny are the stress tests in which a mechanical device or structure is forced over its limits and it breaks down. However, we, the electronics guys, haven’t any visual experiment like that, have we? Of course we have!, and we started to think about them. The first idea was the scheduled batteries vacuum test, but we didn’t want them to explode, we want to use them in our FFUs… So is there something else that we can make to explode? Again the answer is yes, there is! Maybe play with our batteries is not a good idea but, something smaller, like a capacitor? if it is big enough it can store a lot of power and drive it also really fast, am I hearing “short-circuit”? Also big capacitors (a high capacity) used to be electrolytic capacitors, that means that they have polarity, so, if you connect one of them in reverse, what will happen? Let’s see.

Now there are two experiments with capacitors in the air, first charge them and force their discharge by short-circuiting them. The second is just blow up it, by charging it in reverse. The first experiment will produce a brilliant spark, the bigger is the capacitor the most brilliant will be the spark. For the second one, my experience strongly recommend use low capacity electrolytic capacitors, around 10uF since the liquid inside of them doesn’t smells really well after blow it up (Tip: do it in a well venting room). And for exploding them, there are some different ways like connect in reverse and start to increase the power voltage gradually or just set the power source to the highest voltage and current limitation and connect then the capacitor. Each way has a different behaviour! However, remember there is something exploding there, is just a small explosion, but be aware, cover the capacitor with a transparent case before doing….

However, few days ago we hadn’t a venting room ready for the test since we were looking for darkness, and we hadn’t free capacitors neither. Then, how could we make funny experiments? Okay, after thinking a little bit a new idea come up, a new idea like a light bulb, more exactly like the filament… We had a high voltage and high current (over 8A) power source, so, why shouldn’t we try to make a light bulb? This experiment is really easy, you just need a lead and the power source. The lead is mainly build in graphite which is a really good electricity conductor and is really thin, less than 1mm diameter. So, if you force 8A through it, it will dissipate a lot of power, and the only way it has for doing it is in infrared light, and that means hot! That means that during the process you will see it turn from black to red and then to white, a really brilliant white….. The problem is that after some seconds, the lead will break down, but I let you discover by testing how.

Now, moving the text into a more serious area, why is interesting to perform those experiments? it seems they only look for destroying something just for doing it. Okay, I agree, it seems that, but now, let me explain you how can you use that in your future electronics designs and assembling. In the first experiment we have seen what happens when a charged capacitor is short-circuit, it can be even get soldered into another piece of metal if it is big enough. Now imagine that you have one in your board and after switching it off it hasn’t a proper discharging path, and something short-circuit it… That something can be a piece of metal, or even your hand! In the second experiment, okay, a capacitor exploded, now, think that it happens in your board… It’s not nice, and is really easy when you are working under pressure put it in reverse, so, check and double-check after placing them. In the third experiment, a lead have burned out just with current, and it took a lot of current during several seconds, too much seconds for electronics! Now imagine that that lead is one of your components, maybe a resistor?, in your board, and something is wrong and it burns out, have been only that component affected? I don’t think so. Here the conclusion is that using a current limitation in the power source can help you, if you have set it properly nothing will burn and if you pay attention on it, you can turn it off fast enough to save the full circuit….

I hope that you have enjoyed with those experiments and before performing them, please, be sure that someone with electronics experience is controlling them, just for security… And feel free to post new experiments or ideas for them!

A peculiar work day

A “usual” day in the life of an ISAAC member starts only one hour after the Sun wakes up. He rushes through all the daily morning activities while his “Wake up” playlist blasts in the background. As every student can tell you, overcoming the strange force pulling you back under the covers so early in the morning is the toughest battle you’ll probably have to fight the whole day (especially when not enough hours of sleep have been scheduled).

The bus shows up on time, the subway goes every 5 minutes and so, making it in time for the 8:15 ISAAC general meeting is nothing but a trivial matter. The meeting starts. The first thing on the agenda is assigning a minute taker, “randomly” … more often than not. Quick status updates on everything that has been done the past days are being shared as the virtual mic goes around the room. The plan for the next couple of days is also devised. We are behind schedule, the bachelor students must finish their theses in 2 weeks and tiredness can be seen on some of the present faces, but the atmosphere is relaxed and spirits are high.

The meeting finishes with minutes to go until the first lecture of the day starts. Lunch, another lecture, a computer lab and, to top it all up, a one on one session with our mechanics supervisor fill in the next seven hours.  A delight! Walking home, the only thought bouncing around in my head: tomorrow maybe I can wake up at nine…

Setting my personal lament aside I’ll continue the trend and bring you up to date with the design of our Specific Receiver Unit, the RxSU. We have pushed it quite a bit, everything seems to come into place and people’s efforts and work are starting to mix together.

Figure 1

Top view of the RxSU

In the figure above a top view of the unit can be observed. The incoming light should make its way through the aperture set in the side of the unit and hit the first grey rectangular mirror that has a tiny (currently unattached) stepper motor behind it. The motor will act upon the mirror in order for the light to always get across to the beam splitter (orange rectangular plate), through the lens and all the way to the camera sensor.

In the bottom right of the unit the paths for the IR light can be traced out, both of them ending with the IR sensors (the yellow cylinders). The motor spinning the unit and the battery can as well be seen in the middle and top right part of the RxSU. The green shapes show the place where PCBs (Printed Circuit Boards) could be placed in.

The figures bellow depict the same assembly from two different points of view in order to better accentuate on specific aspects of the design. In the first figure the aperture and the mirror can be seen from the perspective of hasty photons rushing in, while in the second figure a 3D view of the whole system is presented.

Point of view of Mr. Photon

Point of view of Mr. Photon

Side view

Side view

 

 

 

 

 

 

We’ve come a long way, there’s still a lot to do but for now sleep takes over.

Good night!

Vlad

RMU, CAD &…well.. CAD again

Hej!

News from the RMU mechanical team can actually be condensed in this article title, CAD – Computer aided designed – of the ejection system is still far from the expected CDR result… However, the RMU team (well okay that used to be only me…) captured an additional member: Antoine, a French student doing his master thesis at KTH.

Brace yourself the team is now 100% French and I know at least one ESA expert that would make a few jokes about it…

Back to business: Last week focus was on the deflection of the aluminium beams supporting the FFU. The maximum weight of one FFU is 2kg. The FFU is in contact with three beams, including two below. It is especially these two last beams that interested us since they are submitted to a 30g x 2 kg = 588.6 N force in the vertical direction due to launch loads. The aim of this analysis was to determine the minimum allowable deflection hence thickness of these supporting beams. Answer is: the two lower beams should be at least 15mm height…Knowing this, we can now design the final version of the vertical support which will maintain the FFU before the ejection.

11.110.RMU_verticalsupport

Don’t panic, this is only a focus on the support maintaining the FFU in the vertical direction with three beams, the current state of the ejection system is more elaborated!

Hope to post more pictures soon! Back to CAD!

Audrey

 

 

The Flying Christmas Tree

As most readers know by now (I hope!), we want to eject two free-falling units (FFUs) from the rocket. Most of the really complicated stuff is on the one we call Rx: It has IR sensors, a tracking camera and all the mechanisms needed to point the sensors towards the other FFU, the Tx. A description of the Rx would certainly fill several blog posts. But in this one I want to talk about the Tx, particularly its mechanical design.

The mission for the Tx is fairly simple: shine as bright as possible! We need two kinds of light sources: the IR sources for the spectroscopy measurements, and visible red light (LED) for the tracking. To pack as many as possible of these lights into the Tx was the first task when starting the mechanical design. And since the shape of the FFU is given as cylindrical, the first idea for the LED boards was to basically just stick them to the wall.

TxSU_assembly v1

The first version of the Tx with the light sources. The red dots are LEDs, soldered onto the green boards. The cylinders are the parabolic mirrors where the IR sources will go inside.

As usual, the first idea is not the best: since the LED boards are flat and the cylinder wall is curved, this solution requires a lot of complicated and expensive machining, it is actually almost impossible to manufacture. After some brainstorming a second version was designed:

TxSU_assembly v2 (frames)

The second version: the LED boards are mounted onto frames, which are part of the unit’s structure.

The version with frames was definitely more realistic than the first one, but still, it is a relatively complicated concept. Thanks to helpful feedback from our supervisors it evolved into a third version, where the frames are replaced by pillars, making the design a bit lighter and simpler.

TxSU_assembly v3 (pillars)

The third version: pillars replace the frames. Also, a mounting for the IR sources is implemented: to avoid too much thermal conduction they rest on three pins.

Still, the pillars are quite complicated parts, with unusual angles and a lot of holes in a small volume. But they are feasible, and this current design is a good compromise with respect to feasibility, cost, weight and space constraints. Having sorted out the placement of the light sources, it is now time to add the other components. That is what I am currently doing, and I also started today to make the drawings of the parts.

TxSU_assembly v3

The current state, now with a few more components: PCBs, batteries. Only a few more small things to add and it will be ready.

 

B.Sc Thesis: 19 Days Left

For the six students who work on the ISAAC project for their B.Sc thesis, the end seems to be getting uncomfortably close now. If I’m not completely misinterpreting the other bachelor students, we would all like to have moths, years or maybe even millennia to finnish all which is not yet finnished.

The appendix, regarding the IR experiment theory is almost complete and the schematic for the IR PCB in RxSU is “getting there” too.

Next time, there will be pictures from the PbS detector and IR emmitter tests, I promise 😉

Respectfully, Mr. Jansson and Ms. de Roos

New problem for wobbling

After a lot of computing and analysis for spin dynamics of FFUs, we finally obtain a reasonable result we thought to perform our further mechanical designs. Raise my head and look at the sunny sky, which lets me feel very promising and delightful.

However, just like the strange weather, suddenly snowing and becoming cold, a new problem for wobbling rates of FFUs appears. I have assumed wobbling rates of 10 deg/s, but a guy from the previous Rexus project has just finished analyzing the RAIN’s(a previous Rexus project) data and computed how the spin axis wobbles throughout the experiment. The RAIN wobbling rates becomes much larger after ejection and He is still investigating why. So We shall discuss his findings and determine which wobbling rates we shall use for ISAAC. So I believe to fulfill this dynamical part, I will have a long way to go. Go on!