Planck Surveyor
previously named
COBRAS / SAMBA
COsmic
Background
Radiation
Anisotropy
Satellite/
SAtellite to
Measure
Background
Anisotropies
Planck will be the third generation CMB space mission
following
COBE and MAP .
Its goal is to get the highest precision, highest resolution
and cleanest maps resulting in the best data and
providing the best test of cosmological models
with the best estimates of cosmological parameters.
Such data will bring cosmology to a new age.
Anticipated & Current ESA/ESTEC Staffing
Planck (formerly COBRAS/SAMBA) is an
ESA (European Space Agency) mission.
The current ESA schedule has a launch date of 2004.
The COBE discovery of anisotropy in the cosmic microwave background radiation
combined with the confirmation and new data of other experiments has opened
a new direct probe of conditions in the early universe.
A high-resolution, high-sensitivity nearly full sky map
of these anisotropies would provide a wealth of new and highly important
cosmological data. These data would relate to three major areas:
- the initial conditions for large scale (galactic and larger) structure form,
- the high energy physics of the early universe, e.g. inflation or
topological defects, and
- the geometry, dynamics, and topology of the universe.
COBRAS/SAMBA, now called Planck, is a mission proposed
to the European Space Agency (ESA).
The COBRAS/SAMBA mission has completed and assessment study and was
judged a viable mission under ESA guidelines.
The COBRAS/SAMBA mission completed its 18 month Phase A Study in May 1996.
At the end of the Phase A Study COBRAS/SAMBA was selected to continue
onto space flight.
There was an ESA meeting in December to review the fate of the
CLUSTER mission which was destroyed in the the Ariane V launch
and the review the Middle Class mission program including COBRAS/SAMBA
which is designated M3 (Middle Class mission #3).
At that meeting COBRAS/SAMBA was reconfirmed.
In January COBRAS/SAMBA was renamed the Max Planck Surveyor mission
or "Planck" for short.
A study is underway to determine commonality with the potential mission
FIRST which has also decided to operate at the Earth-Sun L2 point.
Cosmology is one of the oldest subjects of human inquiry
and at the same time one of the newest sciences.
Questioning the origin and evolution of the Universe
has been a characteristic human endeavor
since before recorded history.
The science of cosmology emerged in this century
when it first became possible to probe great distances
through the Universe.
At first, the observational breakthroughs occurred infrequently.
Hubble discovered the external galaxies and expansion of the Universe
in the 1920's.
Penzias and Wilson dicovered the cosmic microwave background in the 1960's.
The compelling evidence for primordial nucleosynthesis
of the elements amassed during the 1970's and 1980's.
Now the discovery of anisotropy in the cosmic microwave background
allows decisive cosmological tests
because the microwave background directly probes the oldest and
farthest features in the Universe.
Anisotropy measurements that provide a spectrum of precise,
quantitative information would relate to three major areas of cosmology:
- (1) the initial conditions for large scale (galactic and larger) structure
formation,
- (2) the high energy physics of the early universe, e.g. inflation or
topological defects, and
- (3) the geometry, dynamics, and topology of the universe.
In addition to testing cosmological models one will be able to determine
their critical parameters to unprecedented accuracy.
The primary goal of Planck mission is the production of high-sensitivity
(one part per million), high-angular resolution (10 arcminutes) maps
of the microwave sky and thus of the cosmic microwave background.
In addition to having an actual high signal-to-noise map on which one
can do morphological and topological work, the goals include:
Determine the Precise Primordial Fluctuation Spectrum
The first goal is to find to high precision (few per cent or cosmic sample limit)
the fluctuation spectrum over the range from 10 arcminutes to large angular scales.
This provides the information necessary for large scale structure formation theory.
Test Inflation/Primodial Gravity Waves
Detection of primordial gravitons/gravity waves and test of the
relationships expected for inflation.
Statistics of the CMB Anisotropies
The anisotropy statistics reveal information on their source.
Inflation generally predicts a gaussian parent distribution
while topological defects predict deviation from gaussian
distributions and rare peak fluctuations
The statistics of the fluctuations are also important in setting
the time scale for first structure formation.
Small-scale Anisotropies and Reionization
Anisotropy is partially erased on small to medium angular scales
(30 Omega^{1/2} arcminutes) by an ionized intergalactic medium.
A careful measurement can determine or limit the possbility of an
early ionized intergalactic medium and place constraints on or
determine the thermal history of the Universe.
Small-Scale Anisotropies and Galaxy Clustering
10' to 30' corresponds to galactic cluster scales (10h^{-1} Mpc).
Sunyaev-Zel'dovich Effect in Clusters of Galaxies
Low energy CMB photons are scattered by energetic electrons
of the hot intracluster (seen in X-rays) medium. Planck
should collect data on over 1,000 clusters. The ROSAT satellite is
compiling an all-sky X-ray catalog of clusters of galaxies (among other things).
Of particular interest now is the question of the temperature profiles of clusters of galaxies, as this impinges on the use of the Sunyaev--Zel'dovich method
for determining Ho. The combination of Planck and ROSAT data
will be particularly powerful in studying the Sunyaev-Zel'dovich effect.
Information on the potential
Non-cosmological Scientific Results
and alternate discussion of the
Cosmological Scientific Rationale
CMB and Foreground Emissions
The Planck mission is designed to map the sky at multiple frequencies
to both measure the CMB anisotropies and the various Galactic and extragalactic foreground emissions.
Multiple frequencies combined with the known spectral dependence and measurements at very different wavelengths allow the separation of the various components.
foreground emissions gif
More on the Separation of the Foregrounds from the Primordial Fluctuations
Solar System Effects
Emission from the Earth, Sun, and other solar system bodies is the next major concern. The effects of solar system emissions is controlled and minimized by using special far from Earth orbits. Examples are Lagrange Point 2 (L2) of the Earth-Sun system a
Schematic of one considered orbit
Schematic of Baseline Orbit
Spacecraft and Instrument
Artist concepts of the Planck payload, a combined
and a joint Planck/First mission.
More on COBRAS/SAMBA payload
for the Phase A Study (Red Book) version.
More on the Planck Project
The design philosophy is to have very braod frequency coverage
by using both HEMTs (30 - 100 GHz) and bolometers (100 - 850 GHz).
This will provide maximimum discrimination between the foregrounds and CMB.
This also will provide substantial science in addition to the intrinisic
CMB anisotropy imformation.
The broad frequency range requires two technologies and produces a
natural split into the
Low Frequency Instrument (LFI) and
High Frequency Instrument (HFI).
| Instrument |
Technology |
Principal Scientists |
Title |
|
| LFI |
HEMT Amplifiers |
Reno Mandolesi
Marco Bersanelli
|
Principal Investigator
Deputy P.I. |
|
| HFI |
Bolometers |
Jean Loup Puget
J. Lamarre |
Principal Investigator
Instrument Scientist |
|
More Instrumentation Information
Possible US involvement in Planck.
Link to European Space Agency (ESA)
Page for COBRAS/SAMBA now named Planck Surveyor
maintained by Project Scientist Jan Tauber.
Return to the Smoot Group page for a complete description of Dr. Smoot's group's research activities.
Revised 21 January 1997; smoot@cosmos.lbl.gov
