Towards the CAMELOT fleet of GRB detecting nano-satellites: the design concept of the 3U members based on the GRBAlpha and VZLUSAT-2 heritage

Since transient events, such as gamma-ray bursts (GRBs), can be expected from any direction at any time, their detection and localization is difficult. For localizing transient events, we proposed the Cubesats applied for measuring and localising transients mission (CAMELOT), which will be a fleet of nanosatellites distributed evenly on low Earth orbits. As the first step, we designed a technical demonstration for the CAMELOT mission, named GRBAlpha. Even though this 1U satellite has a reduced size scintillator and different mechanical constraints, all the electronic subsystems and communication protocols are the same. GRBAlpha is operating in orbit since 2021 March 22 and it already detected numerous confirmed GRBs. For further details of the early results and ongoing operations see the related presentation at this conference. After this first success, we continue with the design of the 3U prototype of the CAMELOT satellite, which will host an eight times larger detector system integrated into two walls of the satellite. The main difference is the mechanical constraints of mounting the detector in its casing. While for GRBAlpha the reduced sized scintillator is located on the top (Z+) side of the satellite, for CAMELOT it is located on two of the sides. Since the CubeSat standard does not allow enough lateral extension on the sides, the casing has to be sunk into the satellite where it could interfere with the standard PC/104 stacking. Here, we present a solution on how to integrate the scintillator casing, the uniquely designed electronics and commercially available satellite subsystems.