REDEMPTION is an experiment partecipating at REXUS/BEXUS Esa Educational Programme.

The REXUS/BEXUS programme is realised under a bilateral Agency Agreement between the German Aerospace Center (DLR) and the Swedish National Space Board (SNSB). The Swedish share of the payload has been made available to students from other European countries through a collaboration with the European Space Agency (ESA).

EuroLaunch, a cooperation between the Esrange Space Center of the Swedish Space Corporation (SSC) and the Mobile Rocket Base (MORABA) of DLR, is responsible for the campaign management and operations of the launch vehicles. Experts from ESA, SSC and DLR provide technical support to the student teams throughout the project.


Space debris are an increasing problem in space environment for both operative satellites and human activity in space. In according to the most recent international papers, in LEO, there is an already unstable situation that could lead to a degenerative event known as ”Kessler Syndrome”. In order to avoid this situation a lot of research groups are developing technologies able to shift space junk in a safety orbit. Unfortunately, at the moment a feasible system has not yet been found.
Our research group is working, also in collaboration with other universities, industries and agencies, to develop a concrete system to successfully reach the aim. We are proposing a new system based on a sprayed foam that solidifies, which can be used as link between satellite and the debris. This substance is a bicomponent poliuretanic foam which expands and becomes rigid. Since this foam has never been space qualified, we are interested in comparing our ground-tests and our previsions with the real data obtained working in vacuum and microgravity conditions. In particular, we want to check how the reagents mix together, the efficiency of solidification process in terms of mechanical properties of the generated foam, during and after its solidification. These tests will be performed in some dedicated test rooms, which will be allocated inside the module. On the basis of the results of the experiment we will decide if boarding the foam on a nanosatellite for an orbital test. In particular we will board the foam on the satellite that is under development at the II Faculty of Engineering of University of Bologna by our team.

In the past 50 years a lot of satellites have been launched into space, but at the moment only few of them are still operative; these satellites are endangered by the presence of a big amount of unoperative objects which orbit with them. The debris can be generated by explosions, collisions or may be also abandoned satellites. Due to the high velocity, even a very small
fragment can cause huge damages, destroying or fragmenting satellites.
The most overcrowded orbit is LEO, where there are important telecommunication and earth observation satellites, like Goce and Envisat, and where activities with human crew (like ISS and Space Shuttle) take place.
From the 70s, some important scientists like Kessler have theorized the possibility of catastrophic collisions in the space due to orbits overcrowding; today, according to the most recent studies on this problem, the number of debris is increasing.
A very critical point about space debris is that the debris produced by a collision induce at their time more and more collisions. For this reason, considering also future launches and postmission disposal, in the next 200 years there will be an increase of 75% in population growth, with about 1 collision every 4 years.
In order to preserve the near earth environment, the only possible solution is removing existing objects with active technologies (ADR, Active Debris Removal). Even if this situation seems to be very challenging, important researches show that removing only 5 debris per year could be sufficient to stop population growth. That’s why it is very important to find a feasible solution to catch and deplace space debris: it is the aim of our experiment.

Main goal of the experiment:
1. Verify the behaviour of the foam in microgravity and vacuum conditions.
1.1 Investigating efficiency of mixing through static mixers;
1.2 Investigating efficiency of free mixing (collimation of separated reagents sprays on a target);
1.3 Verify solidification process of the foam;
1.4 Verify consistence and mechanical properties of the foam;
1.5 Compare data with tests performed on ground.
In order to consider the experiment successfull, the injection system and acquisition data system should work properly in order to make the reaction occur and to monitorate it, to be able to verify all the carachteristics listed above.

The main goal of REDEMPTION experiment is to verify mixing and properties of the foam generated in near space conditions. In order to achieve this aim, three separated experiment will be performed, each one of them will be allocated in a dedicated sector of the module.
Briefly, in each one of them the injection system will provide the two reagents, which will be mixed in different ways in the test systems: here the reaction occurs. An acquisition system will enable us to check visually the various phases of the foam generation: reaction, expansion and solidification.