Meet the REXUS team: APEX

"If we succeed, we will benefit science. If not, we will have learned a lot." APEX Team

APEX, the Auroral Polarization Explorer is a Payload designed for the nosecone of the REXUS sounding rocket. The goal of APEX is to demonstrate the measurement of the polarization of the aurora borealis, the northern lights.

Auroras are caused by high-energy particles from the Sun interacting with the Earth's upper atmosphere. Therefore, auroras are part of the broader field of space weather, which seeks to understand the plasma environment within our solar system and to predict solar storms that can damage satellites and ground-based infrastructure. Measuring the polarization of the Aurora will be a further piece in the puzzle allowing to constrain models and make better predictions.

To measure the aurora, APEX uses 2 Cameras with band pass filters allowing only light of the red and green aurora to pass. The cameras themselves have polarization filters mounted on the sensor chip to determine the light´s linear polarization. The cameras are installed on a three-axis stabilized gimbal, which will keep the cameras pointing towards the aurora during each multiple seconds lasting exposure. In order to aim the cameras correctly, the system determines the aurora’s position relative to the rocket by using a prediction algorithm in combination with sun sensors and magnetometers (three-axis compasses).

APEX is the first REXUS/BEXUS Project of the Aerospace Team Graz Student association. The association consists of over 90 Members from diverse fields of studies like Physics, Electrical Engineering, Mechanical Engineering, Information and Computer Engineering, Computer Science to name only a few from both the University Graz and University of Technology Graz. Their level of study ranges from Bachelor to PHD candidate. About 15 members of the ASTG are working mainly on APEX, with a large host of other members helping if needed. The APEX - team consists of 5 main directions: Project Management and System Engineering, Science, Mechanics, Electronics, and Software. The team meets weekly for a general update on all systems and has smaller meetings in between to discuss subsystems or work in the ASTG workshop.

APEX Experiment in a nutshell