The Payload sub-system is responsible for the implementation of a payload that will take advantage of the conditions that occur during flight (altitude change, temperature, acceleration, the composition of the air etc.) in a way that might justify its inclusion inside the rocket. Of course, the payload can include more than one experiments, even if their scientific interests differ, as long as there is enough space to include them.
For project SELENE, the Payload sub-system chose to conduct research on environmental radioactivity. The experiment aims to the observation of alterations in the concentration of Radon (Rn-222), a radioactive element, in the lower layers of the atmosphere. In order for the mission to be successful, the team has constructed a detection system that measures the amount of radiation all along the trajectory of the rocket. Specifically, a 3U CubeSat structure houses the experimental set up and, using a drogue parachute, follows a separate path after its deployment from the rocket at apogee. Without the rocket’s tube blocking the incoming radiation, the payload is free to make the necessary measurements. Since it descents independently from the rocket, it is essential to implement a Global Positioning System (GPS) (Read more about it here), as well as all electronics systems to acquire and store data.
When the payload reaches the ground, the experiment comes to an end. Comparing the altitude at which each measurement was taken, the members are able to determine the alteration of Rn-222 in accordance to the altitude. The data are processed during the flight, using a program developed by the team, stored in an SD card and sent through the use of a telemetry system currently developed by the Avionics sub-system (Read more about that here).
The experimental set up has been determined and the necessary procedures have been followed towards its completion.