Planck early results. II. The thermal performance of Planck^⋆

¹ Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
² Agenzia Spaziale Italiana Science Data Center, c/o ESRIN, via Galileo Galilei, Frascati, Italy
³ Astroparticule et Cosmologie, CNRS (UMR 7164), Université Denis Diderot Paris 7, Bâtiment Condorcet, 10 rue A. Domon et Léonie Duquet, Paris, France
⁴ Astrophysics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK
⁵ Atacama Large Millimeter/submillimeter Array, ALMA Santiago Central Offices, Alonso de Cordova 3107, Vitacura, Casilla 763 0355, Santiago, Chile
⁶ CITA, University of Toronto, 60 St. George St., Toronto, ON M5S 3H8, Canada
⁷ CNES, 18 avenue Édouard Belin, 31401 Toulouse Cedex 9, France
⁸ CNRS, IRAP, 9 Av. Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
⁹ CaliforniaInstitute of Technology, Pasadena, California, USA
¹⁰ Centre of Mathematics for Applications, University of Oslo, Blindern, Oslo, Norway
¹¹ DAMTP, University of Cambridge, Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA, UK
¹² DSM/Irfu/SPP, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
¹³ DTU Space, National Space Institute, Juliane Mariesvej 30, Copenhagen, Denmark
¹⁴ Departamento de Física, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo, Spain
¹⁵ Department of Astronomy and Astrophysics, University of Toronto, 50 Saint George Street, Toronto, Ontario, Canada
¹⁶ Department of Physics & Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, Canada
¹⁷ Department of Physics, Gustaf Hällströmin katu 2a, University of Helsinki, Helsinki, Finland
¹⁸ Department of Physics, Princeton University, Princeton, New Jersey, USA
¹⁹ Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, Indiana, USA
²⁰ Department of Physics, University of California, Berkeley, California, USA
²¹ Department of Physics, University of California, One Shields Avenue, Davis, California, USA
²² Department of Physics, University of California, Santa Barbara, California, USA
²³ Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois, USA
²⁴ Dipartimento di Fisica G. Galilei, Università degli Studi di Padova, via Marzolo 8, 35131 Padova, Italy
²⁵ Dipartimento di Fisica, Università La Sapienza, P. le A. Moro 2, Roma, Italy
²⁶ Dipartimento di Fisica, Università degli Studi di Milano, via Celoria, 16, Milano, Italy
²⁷ Dipartimento di Fisica, Università degli Studi di Trieste, via A. Valerio 2, Trieste, Italy
²⁸ Dipartimento di Fisica, Università di Ferrara, via Saragat 1, 44122 Ferrara, Italy
²⁹ Dipartimento di Fisica, Università di Roma Tor Vergata, via della Ricerca Scientifica, 1, Roma, Italy
³⁰ Discovery Center, Niels Bohr Institute, Blegdamsvej 17, Copenhagen, Denmark
³¹ Dpto. Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
³² European Southern Observatory, ESO Vitacura, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago, Chile
³³ European Space Agency, ESAC, Planck Science Office, Camino bajo del Castillo, s/n, Urbanización Villafranca del Castillo, Villanueva de la Cañada, Madrid, Spain
³⁴ European Space Agency, ESOC, Robert-Bosch-Str. 5, Darmstadt, Germany
³⁵ European Space Agency, ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
³⁶ Helsinki Institute of Physics, Gustaf Hällströmin katu 2, University of Helsinki, Helsinki, Finland
³⁷ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, Padova, Italy
³⁸ INAF – Osservatorio Astronomico di Roma, via di Frascati 33, Monte Porzio Catone, Italy
³⁹ INAF – Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, Trieste, Italy
⁴⁰ INAF/IASF Bologna, via Gobetti 101, Bologna, Italy
⁴¹ INAF/IASF Milano, via E. Bassini 15, Milano, Italy
⁴² INRIA, Laboratoire de Recherche en Informatique, Université Paris-Sud 11, Bâtiment 490, 91405 Orsay Cedex, France
⁴³ INSU, Institut des sciences de l’univers, CNRS, 3 rue Michel-Ange, 75794 Paris Cedex 16, France
⁴⁴ IPAG: Institut de Planétologie et d’Astrophysique de Grenoble, Université Joseph Fourier, Grenoble 1/CNRS-INSU, UMR 5274, 38041 Grenoble, France
⁴⁵ ISDC Data Centre for Astrophysics, University of Geneva, Ch. d’Écogia 16, Versoix, Switzerland
⁴⁶ Imperial College London, Astrophysics group, Blackett Laboratory, Prince Consort Road, London, SW7 2AZ, UK
⁴⁷ Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
⁴⁸ Institut Néel, CNRS, Université Joseph Fourier Grenoble I, 25 rue des Martyrs, Grenoble, France
⁴⁹ Institut d’Astrophysique Spatiale, CNRS (UMR8617) Université Paris-Sud 11, Bâtiment 121, Orsay, France
⁵⁰ Institut d’Astrophysique de Paris, CNRS UMR7095, Université Pierre & Marie Curie, 98bis boulevard Arago, Paris, France
⁵¹ Institut de Ciències de l’Espai, CSIC/IEEC, Facultat de Ciències, Campus UAB, Torre C5 par-2, Bellaterra 08193, Spain
⁵² Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan
⁵³ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁵⁴ Institute of TheoreticalAstrophysics, University of Oslo, Blindern, Oslo, Norway
⁵⁵ Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, La Laguna, Tenerife, Spain
⁵⁶ Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), Avda. de los Castros s/n, Santander, Spain
⁵⁷ Istituto di Fisica del Plasma, CNR-ENEA-EURATOM Association, via R. Cozzi 53, Milano, Italy
⁵⁸ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California, USA
⁵⁹ Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
⁶⁰ Kavli Institute for Cosmology Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
⁶¹ LERMA, CNRS, Observatoire de Paris, 61 avenue de l’Observatoire, Paris, France
⁶² Laboratoire AIM, IRFU/Service d’Astrophysique – CEA/DSM – CNRS – Université Paris Diderot, Bât. 709, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
⁶³ Laboratoire Traitement et Communication de l’Information, CNRS (UMR 5141) and Télécom ParisTech, 46 rue Barrault, 75634 Paris Cedex 13, France
⁶⁴ Laboratoire de Physique Subatomique et de Cosmologie, CNRS/IN2P3, Université Joseph Fourier Grenoble I, Institut National Polytechnique de Grenoble, 53 rue des Martyrs, 38026 Grenoble Cedex, France
⁶⁵ Laboratoire de l’Accélérateur Linéaire, Université Paris-Sud 11, CNRS/IN2P3, Orsay, France
⁶⁶ Lawrence Berkeley National Laboratory, Berkeley, California, USA
⁶⁷ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
⁶⁸ MilliLab, VTT Technical Research Centre of Finland, Tietotie 3, Espoo, Finland
⁶⁹ National University of Ireland, Department of Experimental Physics, Maynooth, Co. Kildare, Ireland
⁷⁰ Niels Bohr Institute, Blegdamsvej 17, Copenhagen, Denmark
⁷¹ Observational Cosmology, Mail Stop 367-17, California Institute of Technology, Pasadena, CA, 91125, USA
⁷² Optical Science Laboratory, University College London, Gower Street, London, UK
⁷³ Rutherford Appleton Laboratory, Chilton, Didcot, UK
⁷⁴ SISSA, Astrophysics Sector, via Bonomea 265, 34136, Trieste, Italy
⁷⁵ SUPA, Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
⁷⁶ School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF24 3AA, UK
⁷⁷ Space Sciences Laboratory, University of California, Berkeley, California, USA
⁷⁸ Stanford University, Dept of Physics, Varian Physics Bldg, 382 Via Pueblo Mall, Stanford, California, USA
⁷⁹ Thales Alenia Space France, 100 boulevard du Midi, Cannes la Bocca, France
⁸⁰ Universität Heidelberg, Institut für Theoretische Astrophysik, Albert-Überle-Str. 2, 69120, Heidelberg, Germany
⁸¹ Université de Toulouse, UPS-OMP, IRAP, 31028 Toulouse Cedex 4, France
⁸² University of Granada, Departamento de Física Teórica y del Cosmos, Facultad de Ciencias, Granada, Spain
⁸³ University of Miami, Knight Physics Building, 1320 Campo Sano Dr., Coral Gables, Florida, USA
⁸⁴ Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478 Warszawa, Poland

Received: 10 January 2011
Accepted: 10 August 2011

Abstract

The performance of the Planck instruments in space is enabled by their low operating temperatures, 20 K for LFI and 0.1 K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could satisfy these needs; a helium cryostat, as used by previous cryogenic space missions (IRAS, COBE, ISO, Spitzer, AKARI), could not. Radiative cooling is provided by three V-groove radiators and a large telescope baffle. The active coolers are a hydrogen sorption cooler (<20 K), a ⁴He Joule-Thomson cooler (4.7 K), and a ³He-⁴He dilution cooler (1.4 K and 0.1 K). The flight system was at ambient temperature at launch and cooled in space to operating conditions. The HFI bolometer plate reached 93 mK on 3 July 2009, 50 days after launch. The solar panel always faces the Sun, shadowing the rest of Planck, andoperates at a mean temperature of 384 K. At the other end of the spacecraft, the telescope baffle operates at 42.3 K and the telescope primary mirror operates at 35.9 K. The temperatures of key parts of the instruments are stabilized by both active and passive methods. Temperature fluctuations are driven by changes in the distance from the Sun, sorption cooler cycling and fluctuations in gas-liquid flow, and fluctuations in cosmic ray flux on the dilution and bolometer plates. These fluctuations do not compromise the science data.