Cryogenic characterization of the Planck sorption cooler system flight model

TL;DR

This paper reports on the cryogenic testing and qualification of the Planck mission's sorption cooler system, demonstrating its performance and stability in conditions simulating spaceflight.

Contribution

It provides the first detailed cryogenic qualification results of the flight model sorption coolers for the Planck mission.

Findings

Cooling power and temperature stability meet mission requirements

Cryogenic performance validated through extensive testing

System operates reliably within specified temperature ranges

Abstract

This paper is part of the Prelaunch status LFI papers published on JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/1748-0221 Two continuous closed-cycle hydrogen Joule-Thomson (J-T) sorption coolers have been fabricated and assembled by the Jet Propulsion Laboratory (JPL) for the European Space Agency (ESA) Planck mission. Each refrigerator has been designed to provide a total of ~ 1W of cooling power at two instrument interfaces: they directly cool the Planck Low Frequency Instrument (LFI) around 20K while providing a pre-cooling stage for a 4 K J-T mechanical refrigerator for the High Frequency Instrument (HFI). After sub-system level validation at JPL, the cryocoolers have been delivered to ESA in 2005. In this paper we present the results of the cryogenic qualification and test campaigns of the Nominal Unit on the flight model spacecraft performed at the CSL (Centre Spatial de Liege) facilities in 2008. Test results in terms of input power, cooling power, temperature, and temperature fluctuations over the flight allowable ranges for these interfaces are reported and analyzed with respect to mission requirements.