Freezing temperatures, only a few hours of daylight and a tight schedule – despite these challenging conditions, the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) MAPHEUS 10 sounding rocket has been successfully launched. It lifted off from the Esrange Space Center in northern Sweden at 09:07 CET on 06 December 2021. The rocket was powered by a two-stage IM-IM configuration. IM stands for Improved Malemute and refers to the civilian solid-propellant engine derived from the Patriot PAC-2 surface-to-air missile. The first flight of this configuration took place as part of the MAPHEUS 11 campaign in May 2021.
Seven scientific experiments were on board the over 11-metre-long rocket, which has a launch mass of approximately 1.7 tonnes. In the approximately 15 minutes between launch and landing, they reached a maximum altitude of 259 kilometres. After separating from the rocket motors, the payload followed a parabolic flight profile. Microgravity prevailed for six minutes while the experiments were conducted. The payload landed after being decelerated by a parachute and was successfully recovered by helicopter.
What exactly happens at the microscopic level during the melting and solidification of metallic alloys? It is important to understand the processes that take place in detail because they decisively determine the properties of the alloys. This knowledge is fundamental for numerous manufacturing processes in mechanical engineering and construction as well as in electrical engineering and electronics. The DLR Institute of Materials Physics in Space has developed the AeRogel TEchnology for Cast alloys (ARTEC) experimental module for these investigations. It includes five furnace facilities. As part of the MAPHEUS 8 research campaign, ARTEC has already been used to melt and solidify various aluminium alloys during flight. These were samples with a mass of eight to nine grams. The current MAPHEUS mission continued these experiments. "Under microgravity, effects caused by gravity, such as convective flow, are diminished and other effects that have a weak impact, as well as effects that are usually 'hidden behind', gravity can be investigated. This allows us to develop more accurate models and better describe the relationships between process parameters, structure and properties," explains Sonja Steinbach, a researcher at the DLR Institute of Materials Physics in Space. The research work is taking place in cooperation with European companies from the foundry industry, as well as universities and research institutions.
The Metal-based Additive manufacturing for Research and Space applications (MARS) experiment also travelled into microgravity for the second time. During its first flight with MAPHEUS 11 in May 2021, it was possible to manufacture a workpiece measuring approximately three by four centimetres from metallic glass in space for the first time. These materials are characterised by extremely high strength and corrosion resistance. 3D printing, also referred to as additive manufacturing, was used for this. The material is applied layer by layer until a three-dimensional component is created. The MARS experiment carries out and monitors this process fully automatically in microgravity. "Additive manufacturing processes have several advantages – they are flexible, fast, enable highly complex shapes to be created and produce little material residue. This is why they are extremely interesting not only for applications on Earth, but also in space," says Christian Neumann, also from the DLR Institute of Material Physics in Space. Required structures could be manufactured directly in space, for example on orbital platforms or on the surface of the Moon and Mars. This would greatly reduce the transport effort. For the MAPHEUS 10 campaign, DLR researchers have further optimised the processes and tested additional materials.
Active movement is an important characteristic of many living creatures. They reproduce in this way, follow a food supply, or move away from unfavourable environmental conditions. Microorganisms such as bacteria perform a swimming motion for this purpose. This active movement leads to interesting collective phenomena when a large number of microorganisms come together. These include the formation of structures and swarms. In addition to basic research, this active swimming motion is also of great interest in materials science – for example, to produce synthetic 'active materials'. "Materials in which components use active motion are conceivable, for example to change material properties in a targeted manner when the material is exposed to changing environmental conditions," explains Thomas Voigtmann from the DLR Institute of Materials Physics in Space. The model systems studied in the RAndom motion of MicroSwimmers Experiment in Space (RAMSES) experiment recreate the principles of this collective active motion. Microgravity offers optimal conditions because it helps to prevent the 'swimmers' from migrating to the bottom surface of the experiment.
The multifunctional Multiple Experiment Array (MExA) platform carried four experiments into space and back. Its dimensions are 20 by 30 centimetres. It was developed by the DLR Institute of Aerospace Medicine and the Microgravity User Support Center (MUSC) in Cologne.
How the simplest multicellular organism in the world – Trichoplax adhaerens, a disc-shaped animal – perceives gravity was the focus of one of these four experiments. For this purpose, DLR scientists, together with the University of Veterinary Medicine Hannover and LaTrobe University in Australia, filmed the organism's movement behaviour during the entire flight. This allows them to later evaluate the movement patterns in the laboratory and compare them with control samples on the ground. The placozoa, which are only about 0.5 millimetres in size, have specialised cells that can sense the direction of gravity. "Gravity is the only constant stimulus that has shaped life on Earth over billions of years. Orientation in space is a fundamental property of many organisms and ensures survival. The question we want to answer with our experiment is how did these organisms develop and how did they evolve into humans?" says Jens Hauslage, a gravitational biologist at the DLR Institute of Aerospace Medicine. A new on-board computer, together with a camera, environmental sensors and a control system from the DLR MUSC, transmitted a livestream of the placozoa experiment for the first time. During the flight campaign, the necessary interfaces were tested and the ground system for receiving the livestream and other data was tested.
Two radiation measurement devices were also installed on the experiment platform – the M-42 detector and the EAD Mobile Unit. Both were developed by the DLR Institute of Aerospace Medicine, the latter on behalf of the European Space Agency (ESA). Together, they will be used on the NASA Artemis 1 mission on board the Orion spacecraft, measuring radiation on the way to the Moon. As part of MAPHEUS 10, the researchers carried out functional tests and compared the measurement data from the two devices.
A detailed description of the experiments is available for download on this page.
The MAPHEUS (Materialforschung unter Schwerelosigkeit; material physics experiments under microgravity) high-altitude research programme implemented by the DLR Institute of Material Physics in Space has been operating for 12 years. The annual flights are prepared and carried out by DLR's Mobile Rocket Base (MORABA). They provide researchers with independent and regular access to experiments in microgravity. In this programme, advances in the field of measurement technologies and the realisation of sophisticated flight hardware go hand in hand with cutting-edge experiments, for example in the field of materials and life sciences. Due to the COVID-19 pandemic, the flight schedule has had to be rearranged. Campaign 11 took place first. Campaign 9 is scheduled for January 2022.