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The Bremen Drop Tower

zarm.uni-bremen.de

31–36 of 36 posts

Re: The Bremen Drop Tower

#31
post #4

How does it compare to zero-G planes (vomit comet)? These planes can provide much more than 10 seconds of weightlessness, do it a dozen of times per flight without exceeding 2g of acceleration. Much bigger volume, much bigger payload, people can use it, it looks better in every aspect. By comparison, the drop tower can do three 10-second experiments per day, and the acceleration/deceleration look quite violent. If yo…

Hi, long-time drop tower experimenter here :-) One very good reason to choose a drop tower over the vomit comet is microgravity quality, i.e. residual acceleration and vibrations. The drop tower provides roughly 10^{-6} g, which is a few orders of magnitude better than zero-g aircraft. Another is easy accessibility. You can work on your apparatus until ~2 hours before doing a drop, and you have electronic and mechanical workshops on premises.

Regarding acceleration and deceleration, it's not as bad as it sounds/looks. Most off the shelf component will easily survive, provided you fastened them well enough. Rule of thumb: If it survives shipping by parcel service, it will survive the tower ;-)

Re: The Bremen Drop Tower

#32
post #24
post #4

How does it compare to zero-G planes (vomit comet)? These planes can provide much more than 10 seconds of weightlessness, do it a dozen of times per flight without exceeding 2g of acceleration. Much bigger volume, much bigger payload, people can use it, it looks better in every aspect. By comparison, the drop tower can do three 10-second experiments per day, and the acceleration/deceleration look quite violent. If yo…

Does anybody know why they are limited to three experiments a day? According to Wikipedia, they need 90 minutes to evacuate the tower before every experiment. Does an individual experiment involve multiple (dozens? hundreds?) of falls? I'm assuming they have a long list of people who want to book time in the tower.

Hi, drop tower user here :-) Three drops per day is due to 20 min preparation, 90 min evacuation, 30 min to refill with dried air, 20 min recovery. The is indeed long, which was not anticipate when the tower was first built, this the lack of automatic recover systems. Also, many experiments need to repair/change stuff in their apparatus between drops.

Re: The Bremen Drop Tower

#33

One of the applications for these sorts of microgravity conditions is the creation of large quantum superpositions, especially doing interferometry (roughly, double-slit experiments) with Bose-Einstein condensates. https://physics.aps.org/articles/v6/23

Hey, that's my experiment! :-) So great to see that here on HN.

Re: The Bremen Drop Tower

#34
post #27
post #21

Earlier quoted context omitted.

Wouldn't it be easier to add some rope pulling the capsule to compensate for the air resistance? Or would it add too much "noise" because of the imperfections of such system?

I was thinking a electromagnetic rail controlled by precise sensors combined with very powerful gyroscope would also work. Probably still need to evacuate some of the air.

They're building something similar in Hannover: https://www.hitec.uni-hannover.de/einsteinelevator.html

Re: The Bremen Drop Tower

#35
post #14
post #8

Earlier quoted context omitted.

> in some aspects even better than on the International Space Station (ISS) Woa, does anyone know in what way this tower provides less gravity than the space station?

Perhaps the ISS has more vibration from all those life support systems?

Correct, that's the main problem there. Demanding experiments are even carried out when the astronauts are sleeping, they also tend to vibrate ;-)

Re: The Bremen Drop Tower

#36

Earlier quoted context omitted.

So then something akin to a vacuum chamber in a freefall miner's lift then? Surely cheaper than evacuating the whole chamber.

If that vacuum chamber is falling through air, then it's not in freefall.

So then you accelerate the lift to the correct speed
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