PR³: A system For radio-interferometry and radiation measurement on sounding rockets

The PR³ (Payload for Radio-interferometry and Radiation measurement on Rockets) payload was designed for, and flown on, the REXUS 25 rocket and performed two experiments inside a single module.¹ The first experiment uses radio-interferometry to precisely localize the sounding rocket during flight. An accuracy in the range of 10 cm was expected with an update rate of 1 kHz. In order to achieve this, three antennas mounted on the outside of the module transmit unmodulated carrier signals at three distinct wavelengths around 70 cm. These carrier signals are received by six ground stations placed around the Esrange launch site. Each ground station uses three antennas to perform phase-difference measurements to compute a vector pointing in the direction of the rocket. All six vectors are combined to find a solution of the rocket's position. Since three different frequencies are transmitted, three sources can be identified. This should allow for attitude and accuracy estimation of the system. The second experiment was designed to evaluate whether ionizing radiation can be detected with three types of commercial off-the-shelf camera sensors. A scintillator-based radiation sensor designed for cubesats was also onboard to serve as a reference radiation sensor. Furthermore, three types of commercial off-the-shelf cameras are evaluated. The cameras have different properties with respect to the technique (CCD versus CMOS) as well as different resolutions. Particle interactions are processed on-board and are made available via a telemetry link. Raw data is stored for post-flight processing. The scintillator sensor is used as a reference sensor to compare the camera results against. We present the technical aspects of the experiment design and the obtained results.