Hi everyone for what is likely our last major update before the launch campaign! We recently spent three days at the DLR facilities in Oberpfaffenhofen for the REXUS bench test. For the first time, all four experiments flying on the REXUS 18 mission were connected to the actual rocket service module we are going to use for the flight. The entire flight timeline from countdown to landing was simulated several times. And first and most importantly, the good news is that the test was successful. The experiment and ground station were packaged along with some other essential supplies and are already on their way to Kiruna, where we will rejoin them on the 9th of March.
We did encounter some problems, however. During the shaker test we noticed that we sometimes did not get voltage and current readings from our HDRM. It proved difficult to reproduce the problem, but we suspected a defective contact on one of our electronics boards. After re-soldering everything we could, we thought we had solved the problem, but the issue came up again during the bench test. Unfortunately, we had very little time to localize the problem, but our electronics team is now suspecting the RMC connector between one of our self-made PSIBs and our sbRIO board. It was the only part that required soldering in a reflow furnace, which is something none of us had a lot of experience with, so the error might have occurred there. Another theory is that the spacers between the boards are to blame, since they did not really fit perfectly.
Whatever the reason, this issue is fairly critical. While we don’t necessarily need the data if the mechanism performs as expected, it would be absolutely vital for localizing the problem in case of an experiment failure. On the other hand, since we do not have the experiment anymore and not a lot of time in Kiruna can be spent on troubleshooting, we might end up accidentally destroying an (almost) fully functional experiment. In the end, we were very lucky to get some help from our sponsors and contacts. The Max Planck Institute for Astrophysics, which is located at our university campus in Garching and has a lot of experience with space capable electronics agreed to solder a new RMC connector for us at their electronics workshop, and National Instruments actually gave us a second sbRIO for free, which will allow us to thoroughly test the new hardware before we fly to Kiruna. We are definitely very grateful for that.
In addition to switching out the boards, we will also exchange the HDRM for the final one in Kiruna. It is currently in production and should be finished within the next few weeks.
So that’s it from us for now! We will keep you all updated during the campaign via Facebook and Twitter, so be sure to follow us if you didn’t do so already.
Wish us luck and keep it SMARD!