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The experiment

Such a zero-g experiment wants to be well prepared. After the workshop has cleared the first technical questions, we could begin with the updated construction of the test rig.

Here I first have to thank our technical contact at Novespace, Frédéric Gai, for his help with technical issues and his advice. Especially since at that time it was not completely clear that we would be allowed to fly, because we basically "jumped in" on the ESA campaign in 2015 as commercial participants in the last minute. Here I also need to thank Vladimir Pletser from ESA for his effort to clear the path for our flight.

In the end our participation got confirmed, the contract with Novespace was signed, and meanwhile the four flight participants had been found as well. This was very important, as without their sharing of the costs the participation of the MIRIAM-2 experiment would not have been possible.

In 2017 the story was a bit different, as we already had talked to Novespace before, but again we had to struggle with the funding until we got accepted into the ESA GSTP (General Support Technology Programme) in March 2017. This time the preparation was more formal on the side of Novespace, as they already knew our test rig, but contained more tests on our side.

Farther below you can find our preparations before the 2015 and the 2017 parabolic flights.

Experiment short description

But, to show you what this is all about, here is a short description of the experiment. As already described here, this is about deploying a balloon in space, this means weightlessness. Because to get to space, this balloon must logically be stored in a container to be well protected for launch so it is not damaged.

But how does the balloon get out of its container?

To accomplish this, the MIRIAM-2 team has developed a mechanism consisting of a spring behind the storage container and a steel rope running through two airbag cable cutters and holding together a clamp mechanism. This device hold the balloon in the container until the cable cutters are activated. Then the retention mechanism opens and the balloon can deploy. In the case of the zero-g flight the cutters will be activated manually by a battery-powered switch box.

Preparations 2015

After the two months following the workshop were all in the name of paperwork (making drawings, writing test documentation, Medicals and other paperwork), in September 2015 the building of the test rig and the switchbox for the deployment mechanism could finally begin. In this place, a big thanks needs to be given to Kevin Blaschke, who made all the technical drawings and has contributed to the test rig to be manufactured correctly.

Test setup for functional test of switch box and cutters

In time for the visit of Novespace in the person of Frédéric Gai on September 28, 2015 everything was ready, also thanks to the work of the UniBW workshop staff. The test rig could be inspected and the deployment mechanism could be demonstrated (understandably still without the balloon, because this test is only to happen in weightlessness).

Frédéric inspects the (almost ready) test rig

With transport security device removed, switchbox and cables

Here you can see a video of the deployment test (with dummy in place of the balloon).
At the end of the visit we were told "See you in Bordeaux!" Small remarks and improvements can always be made, these will be implemented in the remaining weeks before the flight.

The balloon before stowage

Switch box for cutter activation

A big thanks also to the company Etforge, for supporting the building and testing of the cutter circuitry.

Presentation of the balloon material

On October 10, 2015 the balloon has been stowed in the container, soon after the testrig was finished.

from left Tanja Lehmann, Klaus Bayler, Christian and Sabine Lagemann with the stowed balloon

The test rig is ready to be taken to Bordeaux

Preparations 2017

Since the parabolic flight in 2015 revealed several deficits on the deployment mechanism, it had to be improved, and additionally some changes on the test rig were necessary. It was also decided that the test will be performed with the original electronics for the sounding rocket flight, which was being developed in summer 2017. Therefore it was as well mounted on the test rig. Additionally a 0g indication was planned, which works with 3-axis acceleration sensors and is also implemented in the flight hardware. Hence as a preparation and to exclude unwanted surprises several more tests had to be performed. The most important ones are described here.

To improve the deployment mechanism, at the University of the Armed Forces Germany in Neubiberg force measurements were performed with a special setup of the balloon container with stowed balloon, and then tests with a balloon dummy, to test the improvements.

On Aug. 12, 2017 finally the balloon was folded and stowed in the improved container at an IABG clean room as usual. Then a deployment test was performed, with unloading of the balloon pod and the "blossom", to see if the deployment works correctly. The correct unfolding of the balloon however could not be tested, since the balloon could not be unloaded and therefore this test can only be done in weightlessness.

A correct deployment as well as the correct functioning of the additional deployment sensors on the balloon container, which are monitored by the electronics hardware, could be verified. During the sounding rocket flight the data of the sensors are to be sent from space to the ground station, to verify the different stages of balloon deployment.

Balloon after the deployment test

To test the 0g sensorics including the software, which is supposed to indicate the achievement of good zero-g conditions during the parabolic flight before the manually initialized balloon deployment and to clear the deployment during the sounding rocket flight, on Sept. 30, 2017 a zero-g flight with a glider was performed.

Klaus Bayler with the test setup in the glider

Tanja Lehmann (pilot) and Klaus Bayler before the takeoff for the glider zero-g flight with a Twin Astir III

On Nov. 11, 2017 another deployment test in the end configuration for the parabolic flight was successfully performed (including software and hardware), then the balloon was folded one last time and packed into its container. Now everything is ready for Bordeaux.

Test setup for the deployment test including spacecraft electronics for surveillance of the deployment mechanism

Test setup with cameras

Here the unloading strings for simulation of weightlessness can be seen

Unfortunately there was no correct indication of the zero-g state. The identified cause was a software flaw, which meanwhile has been corrected.

This was not yet possible for the parabolic flight, so we did it without the indication. But for the sounding rocket flight the recognition of the acceleration sensors must work. Therefore it will be tested again.

Floating circuit board during the test in the glider

Testrig ready for flight