Easter has just started at KTH, and some of us are leaving, some back home, some in holidays, but also some of us are going to stay here in Stockholm….
However that doesn’t mean that ISAAC is going to stop, neither that the ‘fools’ that are going to stay here in Stockholm are going to work for the others. Everybody is going to work, a lot of designs need to be finished, and a lot of decisions need to be taken so in spite of there are not going to be new meetings this coming week, e-mails and files on our common Dropbox folder are going to move around the world.
And also, this coming week is holidays, we are not forgetting that so we are going to relax and enjoy, and then, after Easter, we will be back with our ‘batteries’ fully charged again for keep working on ISAAC!

Have a nice holidays week!


The Storm Before Easter.

As the cold weather seems to loosen its grip on Stockholm, the workload stays the same, but hey… Who feels the urge to enjoy the sunshine when there is noise to calculate and rockets launch? When I look around in the library here at Alfvénlaboratoriet, I can tell you that the answer is “Not ISAAC”.

For me (Johan) and Victoria, work has been progressing and soon we will order our first PCB ever. This will be one of the big moments in the life of a bachelor’s student here at KTH we assume! A few more hours still has to go in to the design of it though.

This PCB, after being populated, will amplify and filter the signal from our PbS detector. It will also convert the analog voltages to a digital interpretation of the output of the amplifier. As for now it looks like the voltages will be stored by a 24-bit ADC with the sampling frequency of 2kSPS.

The next time you will hear from us in E2, we will probabply have some nice photographs of the detector testing for you to feast your eyes upon!


Flight Trajectories

To compute the trajectories of FFUs is not a very important thing, but is still meaningful. In this topic, we want to solve three problems.

1. We are wondering with which velocities and in which directions FFUs should be ejected to make sure that the separation between FFUs in 180 s after ejection is smaller than 2 km.

2. Effects of differential air drag on the rocket and on the FFUs need to be analysed so that the rocket does not block the line of sight between FFUs.

3. What we are also interested in is where the FFUs will land to guarantee that they will not land outside the allowed zone.

And this topic is not a very simple thing either, we need to consider wind speed, ejection angles, atmospheric drag, and the most troublesome factor is the parachute deployment. As we know, when the parachute is deployed, the reference area of FFUs would change, and we use ode45( a matlab function) to solve a set of differential equations, so how to change the parameter of the reference area during ode45 execution? At first, I used if structure in the function differential equations. Unfortunately, this is totally wrong. After a lot of running and debugging this program, I knew that if structure lead to the wrong result. Well, finally, we obtained the reasonable result. So it is worth trying and doing everything. The result is meaningful, while the process teaches me a lot.untitled

Groundhog day: March 20th

If for some strange reason you thought today wasn’t the most special day of the year, keep on reading and you’ll find why you’re wrong.

First of all, after three days of snowing, the weather in Stockholm suddenly changed and the huge snowflakes finally ceased to harass our eyes and nostrils. I know, you might say: “there’s no reason why this should or will happen every year” and I’m going to take a leap of faith here, invoke a correlation and put everything on the account of this special day. It’s not like you’re going to reproduce the exact same conditions, experiment and prove me wrong, right?

The 20th day of March, the day of the vernal equinox, the day when the tilt of the Earth’s axis is neither inclined away or towards the Sun and also the first day of the year, if you happen to follow the Nowrūz calendar. All in all, the day that turns the table bringing sunlight in the foreground and shunning the darkness in the back.

Furthermore today, March 20, 2013 is the first ever International Day of Happiness. So if you were not aware and somehow planned to be sorrowful today or maybe it just happened that you were having a bad day and sulked over it, stop! That attitude is not allowed! Today we take a moment to reflect on what brings happiness into our lives, we acknowledge it as being a good and positive thing and we crack a little smile knowing that tomorrow (since it couldn’t possibly be the 20th of March again) will be worse.

So there you have it! Hopefully you enjoyed yourself today as much as I did, but if not, don’t despair there are only 365.25 days until the most awesome day of the year comes around again.

To top it all off, boost the greatness of this day and cover this little post in a mystery veil, one more reason why today is majestic can be found on our Facebook page. It’s nothing personal, or is it…


Diary of an ejection system

We are now between Preliminary Design and Critical Design Review (due for June)… which means that it is time to come up with our final design of the ejection system!

As my fellow team members have nicely designed two 240 x 80 mm ( diameter x height) FFUs, it is now my duty to fit them in the RMU (348mm inner diameter / 300mm height) along with the ejection system, the sun sensor, the umbilical connections and all the electronics (please refer to Jorge!). Basically, I have to IKEA-style put a lot of components in a not-so big  REXUS cylinder module.

The attempts to find the perfect solution started some months ago…as it is always nice to have a look at the evolution of a system,  you may find on the following pictures the main steps of the ejection system development, from the “full of mysterious unknown boxes” to the “now we are talking”state.


Proposal – November 2012 – not really any idea of what it should look like


Selection workshop – December 2012: FFUs are on top of each others, rails and reinforcements walls


PDR – February 2013: structure is lighter, the hook systems is now self-disengaging, the FFUs are centered on the same axis to improve the balance of the ejection.


Current state- Mars 2013 – aluminium plates to isolate the other experiments from the hot air entering through our openings, improved hooks

The current ejection system still needs a lot of improvements. The main challenge, among many others, is to eject the FFUs at the same time (balanced ejection) using a pyro cutter.

Wish us luck and wait for the final pictures in a few weeks (I hope).




Today marked the end of a very hectic week for the ISAAC team, the Submission of the revised SED on Monday was closely followed by panicked studying for the end-of-period exams which also took place this week.  This naturally led to a lull in productivity =P! It did not last long however with Electrical and Mechanical team meetings re-focusing everyone in preparation for a very productive next week =).

To update you on the progress of the optical systems: Selection of components is ongoing and dialogue between a number of different companies continues. This dialogue has yielded a lot of valuable information =).To update you on the progress of the thermal analysis: … You are now basically up to date!! =) however some conclusions will be drawn by the end of next week!! =)

Until next time,


Exam week

When everyone disappears from the ISAAC lab and buries their heads in books, or as in my case do a regular exam week cleaning of the apartment and lots of other stuff that seem so much more important than studying, you know it’s exam week. Fortunately me and Saman had our exams on Monday which left the rest of the week free for work. That has not been the case for the others on the ISAAC team since we’ve been quite alone here until today when Georg came back to life and joined us once again. I think the rest will start dropping in here soon as well.

As for the work on the power supply we’re getting results that are much better now if we compare to the results we got when we posted our previous post. It’s not as good as we want it yet, but we’re really close.

I hope the exams went well for everyone and wish you luck to those who have some left.