The drop tower of the Zarm Institute at the University of Bremen gets company: A new, smaller tower …
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The Zarm Institute originally expected that the tower would be ready by the end of this year. But construction was delayed. Now, according to project manager Andreas Gierse, the Gravitower machine should be ready at the end of June. “I hope that in 2021 we will be able to fly an experiment in such a way that we can collect the first scientific data,” says Gierse.
One of the first to want to use the new tower is the US materials scientist Martin Castillo, who has been researching at Bremen University for five years. So far he has been experimenting in the large drop tower, but is longingly waiting for the opening of the small one: “I can hardly wait to use the new tower,” says the 44-year-old. He hopes the Gravitower will make work easier: “There, unlike in the large drop tower, an experiment can be repeated many times a day. “I’ve already done 270 flights in the big tower, but because the air has to be sucked out of the tower after each free flight phase, you can do a maximum of two or three flights a day,” says Castillo. The flight phase is much shorter in the small tower, but up to 120 flights per day should be possible there. “If my experiment goes wrong, I can easily readjust, change a little thing and repeat the experiment,” says the scientist.
The tube is finished, the interior is still being worked on: Project manager Andreas Gierse shows the second drop tower. (Frank Thomas Koch)
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LED displays cannot be used in space
The 44-year-old project manager is researching a new type of material with six students. It’s about a powder that glows and requires very little energy for it. This luminous granulate consists of zinc sulfide and small amounts of other substances. The powder glows even under extreme conditions when other materials reach their limits: In space, LED displays, as we know them from cell phones and laptops, cannot be used, explains Castillo. Astronauts therefore need monitors on a different basis. Castillo’s powder could serve as a phosphor for displays.
The material should also be of interest to anyone who has ever had problems with an empty cell phone battery: Although the new powder needs electrical voltage to glow, it does not require much energy. “The cell phone battery could then be charged for a whole week, the battery could also be significantly smaller,” explains the materials researcher.
But work is still being done on the inside of the Gravitower – the outer shell has long been in place. In the summer a makeshift sled was built, a steel cube that was shot up in the tube: “We have already done a lot of test drives with it,” says Gierse. The final sled is still being worked on. “This is a filigree micro-laboratory that has to be hermetically sealed.” The components for it are complex, says the project manager: “And that’s the trick.” produce, meet and discuss on site exactly how these elements should look. Instead, he had to create long brochures describing the elements. Among other things, this caused delays, said Gierse.
For Martin Castillo’s research, drop towers are essential: “I count the days until the little tower is finished,” he says. Most researchers use the drop towers to observe how their materials react in the flight phase. It is different with Castillo and his team: They don’t test the properties of their fabric, they can only produce it in weightlessness. So you have extremely little time for the production of your luminous powder.
Down to business
Facts about the flight phase
It should be called Gravitower: The second drop tower that is being built at the University of Bremen is only 16 meters high. Up to 120 experiments per day should be possible and weightlessness should prevail for 2.5 seconds. This is made possible by a 4,000 hp engine that speeds up a capsule inside the tower.
The Gravitower is being built by the Zarm Institute at the university, which also operates the previous drop tower. For the new tower, 1.6 million euros were estimated. The majority is financed by the Zarm, with the science authority contributing 600,000 euros.
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