The ESA Planck Satellite

Link to the ESA Planck Mission Web site

I. General project/facility description

1. Overview of the facility/project
   The Planck Surveyor is a dedicated CMB satellite scheduled to launch in 2007 to measure the entire sky in nine frequency bands using coherent, HEMT-amplified radiometers at 30, 40 and 70 GHz and bolometric detectors at 100, 143, 217, 353, 545 and 857 GHz. While initially designed primarily for CMB temperature measurements, it has considerable polarization sensitivity. Comparing Planck to the expected state of the art for ground and balloon-borne experiments 5 years from now, is similar to comparing WMAP to existing experiments. The ground-based and balloon-borne experiments are expected to make deeper polarization maps but over much smaller regions. Planck's coverage of the entire sky is unique and valuable and its wide frequency range will be unsurpassed for understanding foregrounds. Projections for Planck's power spectrum results can be found in the excellent CMB review by Hu and Dodelson (2002, ARAA 40 171).
   Planck is the next generation satellite, both more ambitious and riskier than WMAP. WMAP was designed with emphasis on control of systematics and calibration even at the expense of sensitivity. There are no active coolers (or heaters) on WMAP and as a result the focal plane runs warmer than optimum. To achieve high sensitivity Planck's bolometers require active cooling. WMAP used correlation radiometers with receivers fed by completely separate telescopes pointing 140 degrees apart on the sky, providing simultaneous differencing on these scales. Planck has a single optical system and focal plane shared by coherent and bolometric radiometers. On large scales, it should match the precision of WMAP. On small angular scales and for polarization measurements, however, the inceased Planck sensitivity and angular resolution will allow significant improvements to be made over WMAP.
   Planck's better angular resolution and improved frequency coverage will help with foreground separation, or in going from frequency maps to "component" maps. This is exceedingly important not just at high-ell, but at low-ell. The high S/N maps are vitally important for cross-correlation studies with other maps/wavelengths/probes.
   It is planned to launch Planck in the first quarter of 2007 together with the Herschel satellite. After launch, Planck and FIRST will separate and will be placed in different orbits around the second Lagrangian point of the Earth-Sun System.

2. Managing institution and organization
   Planck is primarily a European Space Observatory (ESO) project with considerable investment (~25%) by U.S. through NASA. The bolometer detectors and are being built at Caltech/JPL and the HEMT amplifiers were developed in the US, as well as the 20K hydrogen sorption coolers. The Planck collaboration is quite large with several international science and instrument teams. See http://www.rssd.esa.int/index.php?project=PLANCK for details of of the Planck management and organization.

3. Funding source(s)
   Roughly $400M ESA and $100M NASA funded. The NASA funds are distributed roughly as $60M for hardware and $40M for data analysis.

4. Construction history and cost
   Future facility:
   Planck is currently in qualification mode and detectors have been shipped to Europe where they are being assembled for testing (some testing has started).

5. Operational history and cost
   Future facility: NA.

II. Technical details

1. Specifics of telescope/instrument
   The Planck optics incorporates a single 1.5 meter aplanatic primary mirror.
   It will measure the the entire sky in nine frequency bands using coherent, HEMT-amplified radiometers at 30, 40 and 70 GHz and bolometric detectors at 100, 143, 217, 353, 545 and 857 GHz. The HEMT amplifier correlation receivers are intrinsically polarized and there are 2 feeds at 30 GHz, 3 at 44 GHz and 6 at 70 GHz. The resolution provided by the 1.5 meter primary ranges from 33' to 14' across these bands.
   There are four unpolarized detectors for each of the bolometer bands, providing excellent frequency coverage and resolution of 9.2' at 100 GHz, 7.1 arcminute at 143 GHz, and 5 arcminute at all the higher frequency bands. The prime polarization sensitivity is provided by four PSB pairs for each of the 100, 143, 217 and 353 channels. The polarization sensitivity for the resulting Planck maps is expected to be of order 5 µK to 6 µK per pixel for the 100 and 143 GHz maps over the entire sky.
2. New capabilities anticipated/planned in next 5-10 years
   NA. There is only the single initial instrument

III. User profile

1. % of "open skies" time
   Planck does not have a "guest observer" program, but there are some general data releases that the community will be interested in. For example, there is a quite rapid Early Release Compact Source Catalog that the US is responsible for producing.
   Other data products that will be made publicly available are:
   • the calibrated time-ordered data
   • the sky maps at 9 frequencies, and in Stokes I, Q, and U
   • the extracted astrophysical component maps (i.e., CMB, synchrotron, etc.)
2. Institutional affiliations of users
   

3. Student access, involvement, usage
   

IV. Science Overview

1. Current forefront scientific programs
   Future facility: NA

2. Major discoveries (through 1999)
   Future facility: NA

3. Science highlights of last 5 years
   Future facility: NA

4. Main future science questions to be addressed
   The primary goal of the Planck Mission is to pursue precision cosmology by carefully characterizing the temperature and polarization anisotropy of the cosmic microwave background radiation on from the dipole to angular scales of 5 arc minutes, corresponding to multiples of 2500. The angular resolution of Planck is a factor of 4 better than WMAP and its senstivity is over an order of magnitude higher.
   The temperature anisotropy measurements will provide increased detail on the damping tail of the CMB power spectrum allowing further constraints on the spectral index of the primordial density spectrum, which in turn will lead to a better constraints on the primordial tensor to scalar ratio. It will also allow increased sensitivity to non-Gaussian features in the primordial density field.
   In addition to enhanced constraints on the scalar spectral index and its running and on non-Gaussianity Planck should provide an order of magnitude better constraint on the matter density and a dramatically improved constraint on the sound horizon at last scattering. This is crucially important for dark energy studies using the baryon oscillation method. It also reduces the error on the distance to last scattering from the current several percent to 0.2%. In addition to huge advances is constraining inflationary models, Planck will constrain the intermediate redshift matter power spectrum shape and amplitude at the percent level.
   Planck's polarization sensitive will allow exquisite determination of the CMB intrinsic E-mode spectrum. In addition to testing the framework for the generation of CMB anisotropy, the Planck E-mode spectrum will lead to better constraint on the extracted cosmological parameters.
   Planck should also detect the signature of the gravitational lensing of the CMB by large scale structure. This should be apparent in the non-Gaussianity of the temperature anisotropy and also in the detection of a B-mode polarization signature on moderate angular scales. This can be used in principle to constrain the equation of state of Dark Energy as well as the mass of the neutrino.
   On large angular scales, of order degree and larger, Planck will explore the level of possible inflationary B-modes, i.e., those caused by primordial gravitational waves. The level of this polarization is expected to weak, however, and only in the most optimistic models would Planck be expected to have a hint of a detection.
   Planck will also provide a catalog of many 1000's of nearby galaxy clusters which can be used to constrain cosmology, in particular the matter density and the normalization of the fluctuation spectrum on scales of ~8 Mpc.
   While not its major goal, Planck will provide incredible resources for non-CMB science. Its high frequency bands which are used to distinguish foregrounds from the CMB, will provide all sky maps of the dusty universe at 5 arc minute resolution. The impact of these maps is likely to be similar to the impact the IRAS maps had in the IR/far-IR.

5. Synergies with other major forefront facilities
   There is a natural synergy of space and sub-orbital experiments. As a space experiment, Planck's all sky coverage will allow it to approach fundamental sample variance limits. Sub-orbital experiments on the other hand, are able to achieve high sensitivity over small areas of sky. Planck is therefore synergistic with the upcoming CMB experiments to be conducted at higher resolution with the South Pole Telescope (SPT) and the Arcminute Cosmology Telescope (ACT). Like WMAP, ground and balloon based small areas surveys will lead the fine scale temperature and polarization measurements, but Planck will provide the definitive measurements at least for the temperature and E-mode anisotropy. Pushing to higher targeted sensitivity and higher resolution will be done by sub-orbital missions.

6. Unique contributions
   All sky maps at moderate resolution, polarization sensitive and throughout millimeter and submillimeter.

V. Education/Outreach activities

1. Visitor facility
   
2. Student programs
   
3. Other (as apply)
   

VI. Documentation/website URLs

1. URL of facility website
   http://www.esa.int/science/planck

2. URL of EPO website
   

3. URL(s) of any brief overviews of project/facility
   See http://www.rssd.esa.int/index.php?project=PLANCK. There are several papers on the instrument, project books and science articles.