Development, Simulation and Testing of Temperature Sensors for the Attitude Determination of the Mascot Asteroid Lander

Abstract

This paper discusses one of the sensor concepts that have been considered for the attitude determination system of the mobile asteroid surface scout (Mascot), flying aboard the Hayabusa2 spacecraft. Newly developed orientation temperature sensor (OTS) are used to acquire temperature readings from multiple sides of Mascot, and determine the orientation of the lander relative to the asteroid surface based on these readings. We describe the modelling and hardware testing of the OTS using different optical surfaces with high and low absorptance and emittance. OTS performance is then evaluated under actual mission conditions to determine which sensor type or combination of sensor types can be used for attitude determination. The results show that both single and multiple sensor type concepts can be used to determine the attitude relative to the asteroid surface. A single type low a, high e sensor provides information on which side of the lander is facing the surface, while a combination of two sensors with identical e and very distinct a makes it possible to determine the direction of the Sun with an error of 5�. While not used as part of Mascot’s attitude determination system due to a response time of 5–10 min, opposed to other available, instant sensor types (optical, photovoltaic), the OTS have been added to the Mascot baseline design as a proof of concept, and to collect additional science data during Mascot’s mission on the surface of 1999 JU3. This provides the opportunity to validate the OTS hardware and concepts as a lightweight, low cost alternative for future missions, and directly compare their performance with Mascot’s other sensor types.