STR (Swarm) Overview

Design

Swarm-STR

The purpose of the Optical Bench (OB) is the transference of the attitude from the extremely precise star trackers to the magnetometer field components. The OB ensures a highly mechanical stable platform for the magnetometer and the star trackers. An exhaustive thermos-mechanical design and analysis is carried out to determine and minimise any thermal gradient that could cause a shift in the relative attitude between the two systems.

The star trackers are very magnetically clean; the separation between the two instruments (STR and VFM) is about 40 cm to reduce magnetic perturbation from the STRs. The exploitation of the symmetric system has resulted in a cylindrical tube holding the VFM sensor, minimising transversal thermal gradients. Emphasis has been on the matching of material parameters, the use of isostatic support interfaces, and a detailed analysis of the loads. The instruments are calibrated as standalone, and once integrated in the OB, an inter-calibration and system verification is carried out to determine the relative orientation between the VFM and STR and to verify that the stability is as required.