Marco Molina

The AMS Star Tracker Thermal Qualification Overview

Four different thermal-vacuum tests were performed on AMICA Star Tracker (AST) in the period March-July 2006 in the space simulator of the SERMS laboratory in TerniItaly. Each of these tests was designed to verify different AST camera design features. The Thermal Balance test was conceived to validate the thermo-elastic model of the instrument and the active and passive thermal control subsystems. The Thermal Vacuum Cycling test was conceived to validate the AST electronics operative and survival temperature limits under vacuum conditions. The worst hot and cold operative and survival limits of the lens and filters in the AST optical system were assessed by means of the “Sun in the lens” and Lens Cold tests.

Modeling of a Real LHP and Integration in a System Level Analysis

An LHP-based thermal control system for cryocoolers on the Alpha Magnetic Spectrometer (AMS-02) has been designed, and analyzed by means of the system level model based on Sinda/Fluint. Integrated with the International Space Station (ISS) model by means of a time-varying sink temperature definition, the performance of LHP-based thermal control is investigated. A parametric analysis is carried out also to understand the influence of critical parameters on the operation of LHP.

The AMS-TOF and ECAL Thermal Tests in Vacuum at SERMS

The AMS-02 experiment is a space-born instrument designed to perform high precision measurements of cosmic rays and γ-ray fluxes on board of the International Space Station (ISS). All the components of the AMS experiment are designed to withstand the mechanical stresses in the launch phase and to operate in vacuum in a wide range of temperatures. In order to verify the performance of the hardware in harsh conditions like the flight ones, all the components of the AMS instruments undergo a severe qualification procedure before the integration into the detector. In this paper, we will report on the thermo-vacuum tests on the L-TOF (Lower Time of Flight) and ECAL (Electromagnetic CALorimeter) detectors, successfully performed in the SERMS laboratory in June and September 2006, respectively.

Technological developments for ultra-lightweight, large aperture, deployable mirror for space telescopes

The increasing interest on space telescopes for scientific applications leads to implement the manufacturing technology of the most critical element, i.e. the primary mirror: being more suitable a large aperture, it must be lightweight and deployable. The presented topic was originally addressed to a spaceborne DIAL (Differential Absorption LIDAR) mission operating at 935.5 nm for the measurement of water vapour profile in atmosphere, whose results were presented at ICSO 2006 and 2008. Aim of this paper is to present the latest developments on the main issues related to the fabrication of a breadboard, covering two project critical areas identified during the preliminary studies: the design and performances of the long-stroke actuators used to implement the mirror active control and the mirror survivability to launch via Electrostatic Locking (EL) between mirror and backplane. The described work is developed under the ESA/ESTEC contract No. 22321/09/NL/RA. The lightweight mirror is structured as a central sector surrounded by petals, all of them actively controlled to reach the specified shape after initial deployment and then maintained within specs for the entire mission duration. The presented study concerns: a) testing the Carbon Fiber Reinforced Plastic (CFRP) backplane manufacturing and EL techniques, with production of suitable specimens; b) actuator design optimisation; c) design of the deployment mechanism including a high precision latch; d) the fabrication of thin mirrors mock-ups to validate the fabrication procedure for the large shells. The current activity aims to the construction of an optical breadboard capable of demonstrating the achievement of all these coupled critical aspects: optical quality of the thin shell mirror surface, actuators performances and back-plane - EL subsystem functionality.

A demonstrator for a Heat Switch for Mars Rover: 1 year of ground testing activities

An Heat Switch, capable of self-regulation of its thermal conductance, has been developed for use on Planetary Exploration Rovers. Based on LHP technology, the Heat Switch includes a completely passive bypass valve, which can regulate the working fluid (propylene) vapour flow to the condenser, in order to prevent the evaporator temperature from falling below a given temperature set point. This allows the heat switch to cope with extremely high external temperature excursions of the outer environment and large internal power dissipation variations, still keeping a remarkable temperature stability on the controlled items and preventing their overcooling. An Heat Switch breadboard has been designed, manufactured and tested in the framework of an European Space Agency technological research programme. The activities have been successfully concluded in August 2008. The Heat Switch design and test results have been described in previous papers. This paper contains the results of the continuation of the thermal test campaign on the breadboard, which has been carried out at Carlo Gavazzi Space for more than one year in the timeframe 2008-2009. Tests have been performed both in the laboratory, at ambient temperature, and in a climatic chamber. Tests focus on those Heat Switch features which had been identified worth to be further investigated in the previous test campaign, namely the startup event and the gravity effects. Also related to the gravity effects, the valve oscillations have been investigated in detail. A large number (hundreds) of startup events has been collected, to analyze them on a statistical basis. Additional important results are the long term stability of the thermal performance parameters, the temperature control capabilities through compensation chamber heater actuation, and the detailed characterization of the condenser temperature profile at different combinations of heat loads and environmental temperatures.