ARIEL FGS Instrument Application Software Definition

Short Description

Starting point / motivation

ARIEL is an ESA M-class mission currently undergoing the definition phase B1. This phase will continue for almost three more years during which the system and instrument design is to be established. ARIEL is an exoplanetary science mission. It will derive the chemical properties of exoplanetary atmospheres by means of transit spectroscopy.

To do so, it is equipped with a 1m-class mirror and two science instruments, the ARIEL Infrared Spectrometer (AIRS) covering the 1.95-7.8 micron range and the Fine Guidance System (FGS), which has three photometric channels in the 0.6-1.2 micron range and one spectrometer channel covering 1.25-1.95 microns.

The FGS, as its name suggests, also delivers high precision centroid information to be used by the spacecraft attitude and orbit control subsystem (AOCS) in a closed loop for guiding. These centroid measurements are done by the FGS Instrument Application Software (IASW), which the Department of Astrophysics of the University of Vienna has taken over to develop.

The work on the software will be based on similar projects like CHEOPS, for which the same team provided the IASW. The centroiding and data processing algorithms that are involved need to be defined and first performance figures need to be acquired.

Contents and goals

The FGS-IASW project allows us to carry out the work to complete the B1 definition phase of the ARIEL FGS IASW. Two payload reviews, the SRR and the PDR are covered by the project period. Our contribution to ARIEL is a key component in the overall mission design. It is being developed as a fully-fledged ECSS application software which carries out instrument control, guiding and on-board science data processing tasks.


The main task of the proposed work is the preparation of the review data packs for the IASW. The primary components of this work package are the software tailoring document, the requirements specification document, the architectural design document, TM/TC ICD, PA plan and application software test plan. These are accompanied by additional documents, such as the software reuse file, the schedulability analysis and technical notes about the science and guiding algorithms to be used.

Expected results

Towards the end of the definition phase, a first version of the IASW will be needed to support interface tests with the spacecraft platform. We will prepare a PC-based instrument simulator running a first to achieve this task.

Project Partners


Vienna University - Institute of Astrophysics

Contact Address

Vienna University - Institute of Astrophysics
Prof. Dr. Franz Kerschbaum
Türkenschanzstr. 17
A-1180 Wien