Browse Publications Technical Papers 2005-01-2987
2005-07-11

Progress in the Alpha Magnetic Spectrometer (AMS-02) Thermal Control System (TCS) Design, Operations Scenarios and Verification Approach 2005-01-2987

This paper updates on the Thermal Control System (TCS) of AMS (Alpha Magnetic Spectrometer). The Shuttle fleet grounding, after Columbia accident February 2003, has caused a delay in the AMS-02 project schedule, allowing to put additional effort on the TCS design optimization. This paper accounts for two-years extended numerical simulations, leading to a stable TCS baseline design.
AMS (shown in Figure 1) is to be installed on the International Space Station (ISS) Starboard segment of the Truss, where it shall acquire data for three years with the Superfluid Helium magnet powered ON. After Superfluid Helium tank is depleted, operations continue taking data with instruments not requiring the magnetic field of the super-conducting magnet; this allows a fine characterization of the spectrum of atoms nuclei, for Solar System human exploration purposes.
AMS payload has a mass of about 6500 kg, and a power budget of about 2kW.
The consolidated design presented in the paper is the result of two years trade-off between scientific requirements (AMS experiment to provide a detailed observations of particles outside the Earth’s atmosphere), STS launch environment and ISS operational constraints.
The AMS-02 TCS is mainly passive, with a heaters-thermostat network with individual lines manual switching capabilities.
The heaters are, at the same time, operational, start-up and survival heaters. A smart power sharing between the lines has been adopted in order never to exceed the allocated peak power budget of 3KW, in particular when power is supplied again to the experiment after periods of power outage.
All the AMS-02 operational envelope has been thermally characterized: from STS cargo bay when on the launch pad, to the flight to the ISS, to the transfer from the STS to the ISS and finally on the ISS nominal configuration. The detailed switch-on and checkout phase has been studied providing a timeline for this critical phase of the mission.
Thermal design has been optimized from the point of view of the mass, resulting in less than 5% of the total mass budget of the entire experiment.
The final Thermal-Vacuum Thermal Balance Test is foreseen at System Level January 2007, for a Launch-ready date of September 2007.

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