The European Space Agency's Planck satellite, launched on 14 May 2009, is the third-generation space experiment in the field of cosmic microwave background (CMB) research. It will image the anisotropies of the CMB over the whole sky, with unprecedented sensitivity ( ΔT T ∼ 2 × 10 −6 ) and angular resolution (∼5 arcmin). Planck will provide a major source of information relevant to many fundamental cosmological problems and will test current theories of the early evolution of the Universe and the origin of structure. It will also address a wide range of areas of astrophysical research related to the Milky Way as well as external galaxies and clusters of galaxies. The ability of Planck to measure polarization across a wide frequency range (30−350 GHz), with high precision and accuracy, and over the whole sky, will provide unique insight, not only into specific cosmological questions, but also into the properties of the interstellar medium. This paper is part of a series which describes the technical capabilities of the Planck scientific payload. It is based on the knowledge gathered during the on-ground calibration campaigns of the major subsystems, principally its telescope and its two scientific instruments, and of tests at fully integrated satellite level. It represents the best estimate before launch of the technical performance that the satellite and its payload will achieve in flight. In this paper, we summarise the main elements of the payload performance, which is described in detail in the accompanying papers. In addition, we describe the satellite performance elements which are most relevant for science, and provide an overview of the plans for scientific operations and data analysis.

The European Space Agency's Planck satellite was launched on 14 May 2009, and has been surveying the sky stably and continuously since 13 August 2009. Its performance is well in line with expectations, and it will continue to gather scientific data until the end of its cryogenic lifetime. We give an overview of the history of Planck in its first year of operations, and describe some of the key performance aspects of the satellite. This paper is part of a package submitted in conjunction with Planck's Early Release Compact Source Catalogue, the first data product based on Planck to be released publicly. The package describes the scientific performance of the Planck payload, and presents results on a variety of astrophysical topics related to the sources included in the Catalogue, as well as selected topics on diffuse emission.

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The two science missions Herschel, an observatory-type mission, and Planck, a survey mission, are combined in one program within ESA's long-term science program. This paper deals with Planck. The objective for Planck is to image systematically the whole sky simultaneously with two scientific instruments in nine frequency channels between 30 and 900 GHz to unravel the temperature fluctuations, i.e. the anisotropy, of the cosmic background radiation. Both satellites, have been launched together from the European Space Port in Kourou, French Guiana, on a single Ariane 5 launcher, the orbits will be Lissajous orbits around the 2nd Lagrange Point, "so called" L2 of the Earth-Sun system.This paper gives an overview of the Planck spacecraft including the scientific instruments and the on ground testing.

Since its launch on May 14th 2009 Herschel is the largest telescope of its kind in space. Herschel's 3.5-metre diameter mirror collects long-wavelength infrared radiation from some of the coldest and most distant objects in the Universe. Herschel is the only space observatory to cover the spectral range from far-infrared to sub-millimetre wavelengths. The Herschel satellite is 7.5 metres high and 4 metres wide, with a launch mass of approximately 3.3 tonnes. The bulk of the spacecraft consists of a superfluid liquid helium cryostat inside which three scientific instruments (PACS, SPIRE & HIFI) are operated. Via various cooling stages the instruments are cooled to between a few tens and a few tenths of a degree above absolute zero. This paper gives a brief overview of the spacecraft and the on-ground testing, with an emphasis on the cryogenic issues encountered.