Drop Towers

What is the ZARM Drop Tower?

The ZARM Drop Tower in Bremen, on the campus of the University of Bremen, is one of the tallest and best-known drop tower facilities in Europe. At the heart of the facility is the 146 m high tower surrounded by support facilities that include control rooms, laboratories and hardware workshops. The tower itself houses a steel tube from which air is evacuated prior to the drop and accommodates all the technical components to accelerate, guide and decelerate the capsule.

The capsule is a specially designed bus that is designed to be shockproof, in order to withstand the acceleration / deceleration forces, and pressurised to normal atmospheric pressure and temperature.

In the drop mode, the capsule is released from a height of 120 metres giving 4.74 seconds of microgravity experiment time. The capsule experiences a deceleration of up to 50 g after the experiment is completed.

Since 2007, the Bremen facility has also offered a catapult mode in which the capsule is catapulted vertically to the top of the tower and then drops back down into the deceleration chamber. Using this mode, the microgravity experiment time can be extended from 4.74 to 9.3 seconds. In this mode, the capsule and its enclosed experiment experience an upward acceleration of up to 35 g before the experiment begins. 

Teams wishing to use the ZARM Drop Tower will be granted 5 flight opportunities (5 drops or 5 catapults or any combination thereof).

What is the Gravitower Bremen Prototype (GTB Pro)?

The Gravitower Prototype was inaugurated in 2022 and uses an active system that does not require the evacuation of atmosphere from the tower before the drop.  This greatly decreases operational downtime and provides teams the opportunity to perform numerous sequential drops within minutes of each other. Importantly, the GraviTower Bremen Pro is also capable of performing a controlled flight allowing teams to select the specific level of gravity they wish their experiment to experience, ranging from 10­^-6g to just under 1g. Teams who wish to use the GraviTower may exchange one Drop Tower test for four hours of GraviTower time. This may be relevant to test or tweak the experimental setup prior to committing to a full Drop Tower test as the capsules are interchangeable in both towers.

Enjoy the video below to discover all the platforms! The chapter on ZARM and the Bremen Drop Towers is right at the start.

 

Technical constraints

While defining their projects, applicants should keep in mind the following constraints that apply to the experiments: 

• Physical access to the experiment during the altered gravity periods is not possible, all experiments must therefore be automated;
• Experiments should be designed to run off ~24V batteries;
• The volume inside the capsules is limited;
• Payload mass is limited to 165 kg and 265 kg depending on the capsule selected;
• Point loads should not exceed 50 kg;
• Mass eccentricity should be avoided with a CoG in the centre of the capsule;
• The experiment should withstand 50 g impacts (catapulted experiments should withstand 35g acceleration and should not contain moving parts).

Platform specific documentation

More information about ZARM Drop Tower can be found on their website and the user guide.

More information about GraviTower Bremen Pro can be found on their website and the user guide.

The Campaign

Following the design development and testing of the experiment, teams must ship or bring their experiment to ZARM premises in time for the campaign. The campaign lasts two weeks with the first week being dedicated to finalising the experiment assembly after shipping, software, and safety checks with ZARM staff and integration into the selected capsule. The second week of the campaign is flight week offering 5 drops/catapults or 5 slots of 4hours of GraviTower (combinations are also possible). At the end of the campaign, experiments are removed from the capsule and shipped or driven back to the team’s institute.