ZARM scientists onboard of the 39th parabolic flight
Refueling an aircraft in the air is nothing new. But how can we perform this maneuver in space under microgravity? Future long-term exploration missions will require a concept for propellant filling-stations and ZARM scientists address this challenge "Zero Boil-Off Tank Experiment – Refuelling and Transfer" on the 39th parabolic flight campaign of the DLR.
Press release by DLR:
Premiere for 'Spacebike', the Zero Boil-Off Tank Experiment, and 'CoolFly'
The 39th parabolic flight campaign of the German Space Agency at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) is taking place in Bordeaux for the first time in two years, from 29 August to 8 September 2022. "We're delighted to be returning to the 'old home' of DLR parabolic flights after four campaigns that took place from the airport in Paderborn due to the COVID-19 pandemic," says Katrin Stang, Parabolic Flight Programme Manager for the German Space Agency at DLR. "The conditions in Germany were very good, but the infrastructure in Bordeaux is optimal for our needs following more than 20 years of parabolic flights with the company Novespace."
Over the course of the campaign, ten experiments from the fields of biology, human physiology and materials science, technology and physics will set off into microgravity conditions from the A310 ZERO-G's home base in France. New to the programme are the 'Spacebike' experiments, in which test subjects pedal under conditions representative of spaceflight, the 'Zero Boil-Off Tank' experiment for fuelling spacecraft, and 'CoolFly', which examines the effect of cooling clothing on the human circulatory system. The seven other experiments have flown in previous campaigns. The data acquired during these experiments will be expanded using new test participants, adding new questions or by testing new materials. The experiments will be conducted over three flight days from 6 to 8 September, and, for the first time, a blogger from Flightradar24 will also be on board.
Spacebike – sweating in microgravity
The 'Spacebike' experiment by researchers from the German Sport University Cologne and the University of Applied Sciences FH Aachen will investigate the extent to which the control of human muscles by the brain changes during 'normal' movement under microgravity conditions. For this purpose, test persons ride on a stationary bicycle ergometer, the 'space bike', while the central nerve activity in the brain is recorded by means of electroencephalography (EEG) and the resulting activation of the muscles by means of electromyography (EMG). The analysis of the data will reveal whether there are differences compared to the nerve activity under normal gravity and how the respective motor function is influenced by this. The research topic is not only interesting for spaceflight and exploration, but also for the rehabilitation process in cases of brain damage, such as that caused by a stroke.
Zero Boil-Off Tank – the filling station in orbit
Specialised technologies have enabled aircraft to be refuelled in the air for many years. Refuelling spacecraft and satellites in space, on the other hand, is not possible, even today. The research project 'Zero Boil-Off Tank Experiment – Refuelling and Transfer' aims to help change this. The main problem with refuelling in orbit is that the capillary forces within the propellant tank, depending on their size and acceleration, dominate in microgravity conditions. This influences the liquid and gas phase of the fuel to the point that there is no way to ensure that the fuel is not in the liquid phase at the outlet of the tank as desired, or that the gas outlet is free of liquid.
Refuelling in space would be a great advantage as it could significantly extend the life of satellite missions. In addition, future long-term missions will require the storage and transfer of propellants in space. During the parabolic flight, researchers from the Center of Applied Space Technology and Microgravity (ZARM) at the University of Bremen want to test a concept for the filling and transfer of liquid propellants under microgravity conditions. Successful implementation is the prerequisite for a planned German-US experiment on board the International Space Station (ISS).
CoolFly – cooling for the human circulatory system
The human body has the ability to maintain stable blood pressure when moving from lying or sitting to an upright position. This is known as orthostasis. However, strong accelerations or alterations in gravity, such as those to which astronauts are exposed, often lead to health problems. In the 'CoolFly' parabolic flight experiment, Charité Berlin is investigating the extent to which a slight reduction in body temperature achieved by cooling clothing has a stabilising effect on the participants' orthostasis. "We're very happy that all of the participants tolerated the experiment well. According to them, the cooling works excellently. We're eagerly awaiting the evaluation of the data," says Oliver Opatz, summing up the first flight day.
If the researchers succeed in proving this positive effect, such cooling clothing could be used in spaceflight in the future, especially on long-term missions to the Moon or Mars. This method would also be interesting for use on Earth in heat stress scenarios, such as firefighter missions or the treatment of intensive care patients in hospitals, where external cooling has shown positive effects on the consumption of certain circulation-stabilising drugs.
DLR parabolic flights
Since 1999, the German Space Agency at DLR has organised regular parabolic flights for biological, physiological, physical, technological and materials science research. The research aircraft, the A310 ZERO-G operated by the French company Novespace, is used once or twice a year for scientific campaigns run by DLR, the European Space Agency (ESA) and the French space agency CNES (Centre national d'études spatiales). A DLR parabolic flight campaign usually consists of three flight days with approximately four flight hours each day, during which 31 parabolas are flown. During each parabola, microgravity conditions prevail for approximately 22 seconds. In total, there are around 35 minutes of microgravity during a flight campaign – in between periods of normal gravitational acceleration and acceleration almost twice as great – which researchers can use for their experiments. Up to 40 scientists can take part in a flight, with between 10 and 13 experiments on board.
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