Autonomous Thermal Simulator for EXOMARS-MicroMED Calibration

Abstract

The paper presents the process innovation introduced by the Autonomous Thermal Simulator (ATS), in the development test campaign loop of space scientific equipment and devices. ATS is a special thermal simulator equipment originally designed to support the ground calibration of "MicroMED", a scientific instrument for the study of Martian environment that will be integrated on the lander of the ExoMars 2020 mission led by the European and Russian space agencies. The development activities of MicroMED before the flight require numerous tests in the laboratory both to calibrate the instrument and to verify its operations and performances under the same operating conditions foreseen during the operations on Mars. The ATS not only meets the specific functional and operational requirements of the development/calibration/set up tests of equipment destined for space missions similar to that of MicroMED but introduces a significant change of the overall testing process: for setting up the instruments, for its calibration, and finally for the qualification and validation. The rationale for introducing this change arises from the observation that the development of MicroMED-like equipment (being sensors, experiments or devices) to be installed on board space platforms, has testing requirements less stringent than the ones related to the spacecraft itself, since the operative environment is not the same. In addition, the execution of tests campaigns for development and qualification of space apparatus, using the conventional equipment/process, results to be money and time consuming, and-utmost important-not so flexible and manageable as the experimenter wishes it to be; one for all, the use of thermal vacuum chambers, which typically simulate the operative s/c external environment, is not always within everyone's reach and their reduced flexibility in any case impacts the rapid development times often necessary for the development of complex space systems. There is also a second aspect to be considered. The very delicate design of some experiments such as MicroMED, which is highly sensitive to temperature values, gradients and time-variations, especially around its inlet components used to collect Mars atmosphere and dust samples, requires its precise calibration. More specifically, the calibration must be carried out both at fixed temperature set points and along specified temperature time-profiles, with homogeneous temperature values at each instant. Well, if the fixed temperature set point can be easily simulated in most of thermo-vacuum chambers, the particularly demanding dynamic requirement cannot be reproduced in traditional test equipment because of their thermal inertial characteristics. ATS represents a unique apparatus that has the main advantage to closely surround the test hardware as a glove, thus guaranteeing suitable reach of abovementioned strict conditions. ATS leads to a significant change and process innovation in this context.