ESA GNC Conference Papers Repository

Ariel (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) is an ESA scientific mission whose mission is to measure the spectrum of a large population of known transiting planets in our galaxy. To achieve this, it has a large telescope and an infra-red spectrometer payload, which has challenging AOCS requirements. The main driving requirements for AOCS are sun angle exclusion zone requirements, which apply from launcher separation, and the fine pointing mode requirements for the observation phase at the sun-earth Lagrange L2 orbit. Fine pointing requires reaction wheels with built-in speed controllers, and using payload Fine Guidance Sensors in the loop. This paper presents an overview of the Ariel mission and the AOCS design, particularly the safe mode and fine pointing mode.