Hello, here are Laura, Fabian and Flo, we are a team of three students from the MSS which has been awarded the opportunity to attend a drop-tower-campagin at the Bremen ZARM facility as part of the ESA sponsored program Drop Your Thesis. We will research the imbibition of a drop of liquid water in a porous medium in zero-gravity. What this means is that we will create a large, spherical droplet of water and bringing it in contact with a porous surface and then watch how the drop is being swallowed into the pores.
For the duration of the campaign we will regularly update this page to keep everybody who is interested up to date on what we are doing. For the latest news be sure to check out our facebook page at:
https://www.facebook.com/DYT2015DroppingDropsForESA
Who are we?
Laura is a master’s student in chemical engineering, she already did her bachelor’s thesis at MSS where she researched horizontally driven granular matter. Her master’s thesis will be on the results of this Drop Your Thesis campaign.
Fabian is master student in mechanical engineering and already an experienced microgravity researcher. During the time of his bachelor thesis at MSS he flew onboard of the Airbus A300 ZERO-G as part of the 54 ESA parabolic flight campaign.
Florian is a bachelor student in chemical engineering, who recently joined the team.
The Experiment
We want to study how a large spherical drop of water interacts with a porous surface. However, it is hard to create a large spherical droplet under earth gravity since it will deform under its own weight and not be spherical anymore. So having the opportunity to conduct our experiment in microgravity is the perfect solution for us. In order to perform our study we have constructed an experimental setup that consists of two main parts. This setup is inspired by an earlier experiment from Prof. Michel Louge and his team at Cornell University. Part one is an apparatus to create an appropriately sized droplet. This is done by filling a hydrophobically coated, split spherical cavity with water (using a tiny syringe). The two hemispheres are initially pressed together by springs. The hemispheres then can be separated by an electromagnet creating a force that counteracts the springs, and a free floating droplet is released. The second part concerns the porous medium, which will sit on a small platform attached to a linear actuator, which, upon division of the half spheres will move it towards the droplet. The whole process is recorded by a high-speed camera.
The image below shows the hear of the experiment, the droplet release mechanism described above.
First Tests
Since we are quite curious we could not wait until we are at the drop tower to test the experiment. So we assembled a makeshift drop capsule by putting the release mechanism, a camera and some batteries into a shoebox. We then dropped the shoebox from the top of our lab room into a trashcan full of styrofoam. To our big surprise this acutally worked quite well and although the time it takes the shoebox to fall down in way to short to conduct the full experiment (there is a reason people go to the droptower after all) we at least could see the spherical drop forming.
Droplet Video:
Integration
Of course we cannot do the experiment in a shoebox in the droptower. The ZARM as the drop tower is officially called has sophisticated capsules into which we have to integrate our setup. To do this we attach all the parts into a metal frame which is inserted into the capsule once we arrive in Bremen. The pictures below show Laura and Flo assembling one of four frames and some views the finished frame. To properly test the experiment before we arrive in Bremen, we have outfitted the frames with batteries and and a pocket camera.
Background
Our experiment builds on previous work done by Prof. Louge and his team of students at Cornell University, so we want to give a big shoutout to them:
Dropping Drops meets Astro Alex
Dropping Drops meets Astro Alex! On Saturday we presented our experiment at „Die Lange Nacht der Wissenschaften“ where Laura and our advisor Jonathan had the opportunity to meet ESA astronaut Alexander Gerst.
FAU Aktuell Article
On 22. Dec. 2015 FAU Aktuell published an article about the experiment called „Der perfekte Wassertropfen – Studierende der FAU am Fallturm in Bremen“. The article can be found here and under Media Coverage.
Süddeutsche Zeitung Article
On 7. Feb. 2016 the „Süddeutsche Zeitung“ published an article called „Ein Tropfen für die ISS“. The article can be found here and under Media Coverage.
