Sunday, May 12, 2013

Launch Campaign - Day 10, Launch of REXUS 13!

Seeing the Launch getting cancelled with shifting blue skies did not make us very confident when we woke up early in the morning and realized it was snowing. But the winds were calm the only problem was the bad sight that could affect the recovery of the rocket. The major part of the team came to the radar hill a few minutes before 5.30 am (the rest had to stay at the ground station).

Not too convincing weather
At 5.30 there was a planned hold for 15 min in the countdown to await the launch window and examine the weather conditions.

Fortunately we could see the haze decreased and the weather got clearer simultaneously as the winds remained calm – we began to hope. At 5.45 the announced that the countdown could be resumed and now we know that only critical weather changes could stop the countdown.

The upcoming 15 minutes were very exciting and nervous:

T - 10m Experiment power is switched on.
T - 8m SOLAR is armed and ready for launch
T - 2m We confirm our readiness for flight
T - 0 Lift off!

So the launch did happen and can be seen here:


At this moment the Esrange crew had done their job and the quality of our still had to be proven:

T + 90s Soldering starts
T + 600s End of flight.

So far so good, the soldering had been performed. But how about the pressure in our chambers? To call the flight successful we had to get vacuum in the vacuum chamber and not lose too much pressure in our pressurized chamber. Regarding the pressurized chamber we hoped for a pressure drop less than 20% ideally below 10%. The results were visualized directly in our ground station:

SOLAR Ground Station - revealing the first flight results
As seen in the pressure graphs the experiment performed really well. The pressure dropped immediately in the vacuum chamber and in the pressurized chamber the pressure did not drop but INCREASED (due to the increased temperature during the soldering).

The (so far) very successful flight was celebrated with a champagne breakfast while the recovery mission started. We still had one concern; had all samples been melted?

After roughly 2.5 hours the helicopter landed on Esrange again carrying the rockets payload.

Due to a main parachute failure and a landing in 35 m/s the nosecone of the rocket was a bit demolished as seen in the picture, but fortunately all experiments had survived the flight.

The REXUS 13 payload immediately after the recovery
"I think you belong to Gryffindor Team SOLAR"

The rocket was disassembled and we could soon start our own disassembly. We opened the chambers one by one and found the following results beneath the hats:

Results for pressurized chamber - looking good!
Results for vacuum chamber - looking good!
As you can see all samples melted as planned and a successful flight was a fact. You can also see how the samples looks like before and after flight here

During the evening we had dinner and a hilarious launch party, which can be summarized with one picture:

Launch Campaign - Day 9, Launch of REXUS 13 ... NOT!

At the eight day the countdown was scheduled to start at 9 am, which it did. The weather seemed to be fine and the sky shifted in blue, but due to heavy winds the countdown was held at T-15m to await better weather. However the winds kept blowing and the resume of the countdown was postponed gradually.

Nice weather for a rocket launch you might think
At approximately 2 pm (playing cards) we heard the insane warning horns and assumed that the countdown was about to resume. We went quickly to the car and drove to the radar hill. At the radar hill we unfortunately realized that the horns did not have anything with the resume of the countdown to do and shortly after that we were also told that the countdown had been cancelled  for the day. The new time for the countdown was set to 3.45 am the next day.

Regarding the warning horns, they almost deserve a blog post for themselves. It’s the craziest sound I’ve ever heard and made me leave the ground more than once. You can think of it as a  very boosted horn of gondor.

Boosted horn of Gondor

Launch Campaign - Day 7-8, Launch of REXUS 14

On the seventh day of the launch campaign the launch of our sister rocket REXUS 14 was scheduled. Due to winds the launch was preliminary postponed to around 2 pm. unfortunately the winds did not calm and the countdown was cancelled and a new time was set; 3:45 am in the morning (night?) next day.

Team SOLAR arrived to the radar hill with a bit too few hours of sleep at approximately 5.30 am with 15 minutes left of the countdown. The winds were still okay, but a hold for 15 min was done to await the launch window at 6 am. After the hold and the remaining 15 min of countdown we could see the rocket fly through the sky and disappear into the clouds. It was really cool and made all of us even more excited about our own upcoming launch.

A video made by one of the teams; the Space Sailors, can be found here:

It shows the deployment of their space sail and additionally some really nice pictures of the Earth seen from above! Watch it, I bet that even a blind person would find it awesome!

Due to the very early launch, we were hopeful that they might plan to launch our rocket as well later during the day, but we were later on told that the launch was scheduled to 11 am the next day, meaning a start of the countdown at 9 am.

After the launch we went to a very special cemetry nearby the launching area:

Rocket left overs
During the recovery of REXUS 14, our rocker REXUS 13 was rolled out and placed at the launcher.

Credit: StrathSat-R
REXUS 13, carrying our experiment is being rolled out and installed on the... 
                          ....launcher!                             .
Over and Out!


Launch Campaign - Day 4-6, Final Testing and Payload Assembly

As planned the bench test was performed during the fourth day of the launch campaign with all experiments performing well. Due to the successful test the flight simulation could be scheduled to the day after.

After a good night’s sleep  Team SOLAR was ready for an early flight simulation, but very unexpectedly the test could not be performed as early as expected and this day offered some card games as well. Fortunately the simulation could be performed with good results a few hours later.

The difference between the bench test and the flight simulation is that the real ground station in Esrange’s main building was used during the flight simulation to simulate the real flight as good as possible.

SOLAR Ground Station                          
After the final tests the last modules could be assembled creating the payload of REXUS 13.


The payloads of REXUS 14 and 13       
During the Sunday the staff took a day off and we could relax before the upcoming flights during the next week.

Friday, May 3, 2013

Day 2-4, the masters of card games

And here we thought launch campaign was a lot of work!

Day 2 of the launch campaign was quite slow. We started the day with doing a simple assembly of the experiment to hook it up to the service module where we did a com-test. In practice this means we check that the communication from our experiment through the service module to the ground station works.
The test ran smoothly so we did final assembly where we assembled the experiment with lock tight and predetermined torque. We then made sure everything was connected as per our procedures. Another com-test confirmed that all connections were still good.
This was all done in the morning which meant we had to wait for the bench test the next day. The rest of the day then mostly involved playing cards.
Final assembly

Day 3 was the day for the bench test. The test was set at 13:00 so we set up our ground station and then waited with some card playing. The time for the bench test then changed to 14:00 then 9:00 the next day, One of the other experiments were having trouble so they would have the night to resolve it. So there was no use putting the cards away.
The team playing cards

Day 4, morning meeting, today is the bench test which is set at 10:00, then after lunch, then 14:00. But as I'm  writing this the bench test is actually being set up. So hopefully the test will start soon and we can start setting up for flight simulation which well be done tomorrow.
The experiments being lined up for bench test. Notice how one experiment is still missing.

Wednesday, May 1, 2013

Launch Campaign - Day 1

During this project we've followed something I'd like to call the SOLAR sine wave. Everything is going perfect until something happens which will make you think "it's all over". The problem then get's solved and your on top of the world again. The launch campaign is no exception apparently.

Yesterday the day started with us dismounting the experiment since we had to change the screws after the bumpy transportation to ESRANGE. That included taking apart the electronics box to see if the micro-SD stored the data as expected. It did, all was well and dandy so we screwed back PCB's into the box. In the meantime we tested out our backup PCB's which had been soldered just last week. For some reason these cards wouldn't let us program the micro controller. We tested the lines on the board but they all seemed fine so we came to the conclusion that it must be the new CPU that is corrupt. Not to fear, we brought a spare and we spent an hour removing the old CPU and soldering on the new one. Of course that did not work either! Well at least we had our flight PCB's functioning, or did we? We switched back to the our old electronics that's been working fine since January but we could not communicate with it from our ground station. Now was the time to panic. After trying everything we took to an old trick, restart the computer. We launched the ground station again and there we go everything is working as expected.
Björn soldering the new micro controller

So what was the problem? It seems the com port we were using on the computer had somehow latched up when trying to program the backup PCB's. Because the compiler didn't get a response from the micro controller it never closed the port. This was later confirmed by reproducing the scenario.

It was still the matter of the backup PCB's though. Why were we unable to program them? We had a lunch to think it over where the payload manager Mikael Inga suggested it might be a different component connected to the programming pins that's causing the problem. The only other component connected to the programming pins was the micro-SD card so we tried removing it worked. We then put the micro-SD back and tried programming again and what do you know that worked as well!
The PCB's that caused all the problem. The PCB with the micro controller is underneath the one displayed.

We're still not quite sure what caused this problem but it could be that some solder in the micro-SD bracket that got removed by taking the card out.
So everything was working great until we once again got the problem that we didn't receive any data to the ground station. After error searching for about two hours we realized we had forgotten to turn the power on.

To brush of an old chestnut, "it's not rocket science"

Tuesday, January 15, 2013

Final preparation before integration week

 After a long and well deserved Christmas break the team is once again in place and working on the experiment. The experiment is fully functional and is mostly verified. So one might expect that we could lean back and enjoy our wonderful work now, but there's a lot more to be done before we can ship our experiment to Bremen in the end of January.
Some of our main points are:
  • Create the box for shipping the experiment
  • Do vibration test with new PCB's
  • Prepare the rocket module with covers over the venting holes
  • Produce multiple sets of soldering setups for integration week
  • Do multiple end to end test with complete system
  • Make PCB's flight ready
  • Implement temperature monitoring of battery packs during charging
  • Implement the sd-backup system
So understandably the team will have to work at full speed for the following two weeks. We are however confident that all the major points will be sorted once it is time to ship everything.

Once the experiment has been sent to Bremen we will send down two team members both named Björn. They are experts on the electrical and software system in SOLAR and could hopefully resolve and issues we could have during integration.
The integration week is pretty much what it sounds like, our experiment will be integrated with the other experiments and the rocket service module to make sure all the interface between different parts of the rocket works as expected.

If we have no major faults in our design the experiment will remain in Bremen before being sent to Oberpfaffenhofen outside Munich. There it will undergo a series of test to verify the flight readiness of our experiment.

So that's what we're working towards right now.
We'll try to get another update out sometime during this week, if not on the blog at least on our facebook page.

Have a nice day :)