The TDP-1 AFIS-P mission was the first mission conducted within the TDP series of experiments. In preparation for the space-based mission, a test of a prototype MAPT detector needed to be conducted under conditions comparable to that on a spacecraft: limited space and power supply, (near-)vacuum and cold temperatures. We inferred that a flight on a stratospheric research balloon would provide most of these conditions, with the exception of low atmospheric pressure instead of actual vacuum. In addition, such a mission would add two more constraints, which similarily exist for a space-based mission: limited or no (physical) access to the experiment and limited downlink bandwith for science data.
The REXUS/BEXUS program offered by the German Aerospace Center (DLR) in cooperation with the Swedish National Space Board (SNSB) and the European Space Agency (ESA) provides student teams with an opportunity to fly an experiment on a stratospheric balloon at heights of 25 - 30 km. The REXUS/BEXUS programme is realized 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). (For more information on REXUS/BEXUS see here)
The proposal for the AFIS-P mission that was handed in to the DLR was accepted in December 2013 and the launch campaign took place in October 2014.
The mission’s goal was to measure the fluxes of different charged particle species in the upper atmosphere. In contrast to all spectrometer-like particle detectors that have so far been flown on balloon missions, the AFIS detector is sensible in the low-energy range of approximately 25 to 100 MeV per nucleon. This is a region where only few data is available for altitudes between 10 km and 30 km.
To make the test of the prototype as realistic as possible, we decided to build the detectors almost exactly as it has to be implemented into a spacecraft. Most importantly, this requires the detector to have the final dimensions to fit into a satellite built according to the CubeSat standard. To achieve this objective the actual structure needed for the spacecraft integration was built around the detector and an adaptor frame was buils to house the remaining systems required for the balloon mission.
The TDP-1 AFIS-P experiment was launched into the stratosphere on October 10, 2014 aboard the BEXUS 18 research balloon from Esrange Space Center in northern Sweden. After a flight of around two hours, the gondola fell back to Earth assisted by a parachute and the experiment was safely retrieved.