The drop experiment: how does it work?

What exactly is TU student and Delta Lab blogger Tim Hermans going to drop in the ZARM Drop Tower?

The ZARM Drop Tower: dropping a capsule is not as easy as it may sound.

In my last blog, I discussed the challenges of designing our experiment set-up. This time, we’ll take a closer look at the actual experiment.hat exactly are we going to drop in the ZARM Drop Tower, and how does it work?

Drop capsule

Over the course of a week in November, we will drop our experiment five times. The experiment set-up will be integrated into a so-called drop capsule. This is a cylindrical capsule with a coned nose. The capsule contains a battery pack and a computer control system. Naturally, there is also room for the experiment set-up in the drop capsule. There are different types of drop capsules available, but we’ll be using the drop capsule which is also suited for catapult launches. In the catapult mode, the capsule is first accelerated upwards before it falls down again, almost doubling the time of microgravity.

The ZARM drop capsule (left) and the integrated experiment set-up (right).

The experiment set-up

The experiment set-up and integration of the set-up into the drop capsule is the part of the development of the experiment that we’re responsible for. The preliminary design of the capsule consists of two containers with ferrofluids in it. Around each container a coil is placed in order to generate a magnetic field that pushes the ferrofluid to the base of their containers.


As soon as the capsule is released in the drop tower, the containers holding the ferrofluid will be moved up and down with two sliders on the left and the right of the set-up. In this way, a known acceleration is exerted on the fluids.


Now, what’s interesting is how the ferrofluids will react to that. How quickly will the magnetic field stop the ferrofluid from moving because of the actuation we apply to it? This behaviour is hard to predict with numerical models, because the force the magnetic field exerts on the ferrofluid is changed by the position of the ferrofluid itself

In order to see what happens in a real experiment, we will project a pattern on the surface of the ferrofluid and make a video of how the pattern distorts over time. Based on that distortion, we can say something about the dynamics of the ferrofluid.

The drop campaign

This drop campaign will take place in November in Bremen, Germany. The campaign lasts two weeks. In the first week we’ll integrate our set-up in the drop capsule and extensively test all our hardware. In the second week, we’ll perform the actual drops. We will do one experiment each day, for a total of five tests.

Dropping the capsule is not as easy as it may sound. The balance of the capsule has to be tested thoroughly before it can be dropped. With each drop, we want to vary the intensity of themagnetic field to see what happens with the ferrofluid. But, before we can go to Bremen, we still have a lot of work to do. Even though, I’m already looking forward to these exciting weeks!

Tim Hermans

Tim Hermans, a master’s student in space exploration, participates in the ‘Drop Your Thesis!’ programme at the European Space Agency. This is a hands-on student project in which an experiment will be designed and carried out in microgravity in the ZARM Drop Tower in Bremen, Germany. The exciting but challenging programme requires hard work and careful management and planning. The coming year, Tim will post monthly blogs every last Friday of the month about his experiences and the ups and downs of his project. You can follow Tim’s project team on Facebook as well.

Also read:

ESA Education’s ‘Drop Your Thesis!’ programme

The art of outreach

‘Designing the experiment set-up’

Editor Redactie

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