From 2 to 13 September 2019, scientists and engineers from German universities and research institutions travelled to Bordeaux, southern France, to conduct experiments under microgravity conditions. The 34th flight campaign was carried out on board Europe's only parabolic flight aircraft, the A310 ZERO-G, under the auspices of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR). Parabolic flights serve as a 'bridge' to space and are particularly useful as a test platform for experiments designed to fly on the International Space Station (ISS).
Fourteen different teams made the most of the preparation week and the subsequent week of flights to address specific questions from the fields of (fundamental) physics, biology, technology, materials science and human physiology. Matthias Maurer was a prominent experimenter on board. The German ESA astronaut was part of the FLUMIAS team, comprised of scientists from the universities of Frankfurt and Marburg, as well as Airbus in Bremen. FLUMIAS is a fluorescence microscope that can be used to observe cells and tissue, including plant cells, live and with a high three-dimensional and temporal resolution, in microgravity. "Plants are model organisms when it comes to the perception of and adaptation to gravity. They also play an important role in space as sources of food and oxygen, as well as waste regenerators. During the parabolic flight, we investigated the perception of changes in gravity and the early signal transmissions that resulted," explains Maurer. "I found it particularly interesting to see how quickly plants react to microgravity and release messenger substances. I look forward to seeing FLUMIAS on the ISS and possibly even using it myself."
FLUMIAS was developed by Airbus on behalf of the DLR Space Administration for use during parabolic flights and on TEXUS research rockets. Since 2014 it has been offering scientists the opportunity to conduct research on living cells in microgravity. A demonstrator version of a further-developed FLUMIAS – this time the size of a shoebox – was successfully used for the first time to carry out live cell imaging on the ISS in 2018. "The FLUMIAS-ISS project is planned for the future, featuring a perfected version of the microscope that will be made available to researchers from Germany – and from other countries – in cooperation with ESA," explains DLR Parabolic Flight Programme Manager Katrin Stang.
Matthias Maurer – who holds a doctorate degree in materials science – also worked as an 'associate team member' on the 'Flying OCULUS' (Optical Coatings for Ultra Lightweight Robust Spacecraft Structures) experiment. In this project, a process to metallise the surfaces of carbon-fibre composite materials was developed in cooperation with the Institute of Space Systems at Technische Universität Braunschweig, INVENT GmbH and the Fraunhofer Institute for Surface Engineering and Thin Films. The aim is to produce space-compatible, lightweight and cost-saving mirror systems for applications such as space telescopes. "During the parabolic flight, we tested the concept and mechanics of deploying a lightweight mirror that was 75 percent lighter than conventional space-based mirror systems. It was installed in a CubeSat small satellite," says Maurer. "Lightweight construction is a key topic for spaceflight. It costs over 10,000 euro to transport each kilogram into space. The system worked successfully in microgravity conditions."
The DLR Institute of Materials Physics in Space, which is based in Cologne, working in cooperation with the German Federal Institute for Material Research and Testing and the DLR Institute of Robotics and Mechatronics in Oberpfaffenhofen, near Munich, also took part in the campaign with ECOS, an experiment for teleoperated applications ('human–machine interaction'). ECOS uses an interface that electrically senses muscle activity and generates control signals by monitoring the contraction of different muscle groups. In addition to teleoperation, this technology is also interesting for prosthetic applications.
The reason why parabolic flight campaigns are of such interest to researchers are the same today as they were 20 years ago. "Gravity always prevails on Earth. But what exactly happens in biological or non-biological systems once gravity no longer exerts an influence? Using a special flight manoeuvre, parabolic flights allow gravity to be 'suspended' for a short period of time, because the various forces acting on the aircraft and its occupants cancel one another out. This is ideal for studying many of the open questions in biology, human physiology, materials research and physics that cannot be resolved on Earth, as well as allowing us to be as prepared as possible for space exploration," explains Katrin Stang.
The only way to conduct research in microgravity on Earth or in its immediate vicinity is to carry out experiments in drop towers, research rockets or, if humans are to be involved, on parabolic flights. German scientists have been using parabolic flights since the 1980s, back then as part of an ESA programme or through collaboration with other space nations. The first independent DLR campaign took place 20 years ago – in December 1999 – with eight scientific experiments on board, including preliminary and accompanying experiments for the first plasma crystal experiment on the ISS (2001–2005). "The experiments performed in 1999 laid the groundwork for the subsequent, highly-successful series of German-Russian plasma crystal experiments on the ISS," says Stang. As part of the 34th campaign, a new experiment from the DLR Institute of Materials Physics in Space was on board, to further advance research in the field of plasma crystals.
The company Novespace organises research flights on behalf of the European Space Agencies ESA, CNES and DLR. Until 2014 these flights used a converted Airbus A300 ZERO-G. Since 2015, its successor, an Airbus A310 ZERO-G, has been in service.