Planck is a
space observatoryA space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects...
designed to observe the
anisotropiesAnisotropy is the property of being directionally dependent, as opposed to isotropy, which implies homogeneity in all directions. It can be defined as a difference, when measured along different axes, in a material's physical property An example of anisotropy is the light coming through a...
of the
cosmic microwave background (CMB)In cosmology, cosmic microwave background radiation is a form of electromagnetic radiation filling the universe. With a traditional optical telescope, the space between stars and galaxies is pitch black...
over the entire sky, using high sensitivity and
angular resolutionAngular resolution or 'spatial resolution' describes the resolving power of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye.- Definition of terms :...
. Planck was built in the
Cannes Mandelieu Space CenterThe Cannes Mandelieu Space Center is an industrial plant dedicated to spacecraft manufacturing, located on both towns of Cannes and Mandelieu in France...
by
Thales Alenia SpaceThales Alenia Space is the company born after Thales had bought the participation of Alcatel in the two joint-ventures between Alcatel and Finmeccanica, Alcatel Alenia Space and Telespazio.-History:...
and created as the third Medium-Sized Mission (M3) of the
European Space Agency's|owner = |headquarters = Paris|spaceport = Guiana Space Centre|image = ESA LOGO.svg|size = 240px|acronym = ESA|established = 1975|administrator = Jean-Jacques Dordain...
Horizon 2000 Scientific Programme. The project—initially called COBRAS/SAMBA after its approval—is named in honour of the German scientist
Max PlanckMax Planck was a German physicist. He is considered to be the founder of the quantum theory, and thus one of the most important physicists of the twentieth century. Planck was awarded the Nobel Prize in Physics in 1918.-Biography:Planck came from a traditional, intellectual family...
(1858–1947), who won the Nobel Prize for Physics in 1918.
The mission will complement and improve upon observations made by the
NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
Wilkinson Microwave Anisotropy ProbeThe Wilkinson Microwave Anisotropy Probe — also known as the Microwave Anisotropy Probe , and Explorer 80 — is a spacecraft which measures differences in the temperature of the Big Bang's remnant radiant heat — the Cosmic Microwave Background Radiation — across the full sky. Headed by Professor...
, which has measured the anisotropies at larger angular scales and lower sensitivity than Planck.
Planck is a
space observatoryA space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects...
designed to observe the
anisotropiesAnisotropy is the property of being directionally dependent, as opposed to isotropy, which implies homogeneity in all directions. It can be defined as a difference, when measured along different axes, in a material's physical property An example of anisotropy is the light coming through a...
of the
cosmic microwave background (CMB)In cosmology, cosmic microwave background radiation is a form of electromagnetic radiation filling the universe. With a traditional optical telescope, the space between stars and galaxies is pitch black...
over the entire sky, using high sensitivity and
angular resolutionAngular resolution or 'spatial resolution' describes the resolving power of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye.- Definition of terms :...
. Planck was built in the
Cannes Mandelieu Space CenterThe Cannes Mandelieu Space Center is an industrial plant dedicated to spacecraft manufacturing, located on both towns of Cannes and Mandelieu in France...
by
Thales Alenia SpaceThales Alenia Space is the company born after Thales had bought the participation of Alcatel in the two joint-ventures between Alcatel and Finmeccanica, Alcatel Alenia Space and Telespazio.-History:...
and created as the third Medium-Sized Mission (M3) of the
European Space Agency's|owner = |headquarters = Paris|spaceport = Guiana Space Centre|image = ESA LOGO.svg|size = 240px|acronym = ESA|established = 1975|administrator = Jean-Jacques Dordain...
Horizon 2000 Scientific Programme. The project—initially called COBRAS/SAMBA after its approval—is named in honour of the German scientist
Max PlanckMax Planck was a German physicist. He is considered to be the founder of the quantum theory, and thus one of the most important physicists of the twentieth century. Planck was awarded the Nobel Prize in Physics in 1918.-Biography:Planck came from a traditional, intellectual family...
(1858–1947), who won the Nobel Prize for Physics in 1918.
The mission will complement and improve upon observations made by the
NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
Wilkinson Microwave Anisotropy ProbeThe Wilkinson Microwave Anisotropy Probe — also known as the Microwave Anisotropy Probe , and Explorer 80 — is a spacecraft which measures differences in the temperature of the Big Bang's remnant radiant heat — the Cosmic Microwave Background Radiation — across the full sky. Headed by Professor...
, which has measured the anisotropies at larger angular scales and lower sensitivity than Planck. Planck will provide a major source of information relevant to several cosmological and astrophysical issues, such as testing theories of the early universe and the origin of cosmic structure.
Objectives
The mission has a wide variety of scientific aims, including:
- High resolution detections of both the total intensity and polarization of the primordial CMB
CMB can mean:*Bandaranaike International Airport, Sri Lanka's only international airport *C.M.B., the debut album of American R&B artist Color Me Badd*Cavalier Marching Band, the marching band of the University of Virginia...
anisotropies
- Creation of a catalogue of galaxy clusters through the Sunyaev-Zel'dovich effect
The Sunyaev-Zel'dovich effect is the result of high energy electrons distorting the cosmic microwave background radiation through inverse Compton scattering, in which the low energy CMB photons receive energy boost during collision with the high energy cluster electrons...
- Observations of the gravitational lensing of the CMB, as well as the integrated Sachs–Wolfe effect
- Observations of bright extragalactic radio (active galactic nuclei
An active galactic nucleus is a compact region at the centre of a galaxy which has a much higher than normal luminosity over some or all of the electromagnetic spectrum . A galaxy hosting an AGN is called an active galaxy...
) and infrared (dusty galaxy) sources
- Observations of the Milky Way
The Milky Way, or simply the Galaxy, is the galaxy in which the Solar System is located. It is a barred spiral galaxy that is part of the Local Group of galaxies...
, including the local interstellar mediumIn astronomy, the interstellar medium is the gas and dust that pervade interstellar space: the matter that exists between the star systems within a galaxy. It fills interstellar space and blends smoothly into the surrounding intergalactic space...
, distributed synchrotronA synchrotron is a particular type of cyclic particle accelerator in which the magnetic field and the electric field are carefully synchronized with the travelling particle beam. The proton synchrotron was originally conceived by Sir Marcus Oliphant...
emission and measurements of the galactic magnetic fieldMagnetic fields surround magnetic materials and electric currents and are detected by the force they exert on other magnetic materials and moving electric charges...
.
- Studies of the local Solar System, including planet
A planet , is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
s, asteroidthumb|260px|right|[[253 Mathilde]], a [[C-type asteroid]] measuring about across. Photograph taken in 1997 by the [[NEAR Shoemaker]] probe.Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, especially in the inner Solar System; they are...
s, cometA comet is a Small Solar System Body that has coma and is bigger than a meteoroid. When close enough to the Sun, a comet exhibits a visible coma , and sometimes a tail, both because of the effects of solar radiation upon the comet's nucleus...
s and the zodiacal lightThe zodiacal light is a faint, roughly triangular, whitish glow seen in the night sky which appears to extend up from the vicinity of the sun along the ecliptic or zodiac...
.
Planck represents an advance over WMAP in several respects.
- It has higher resolution, allowing it to probe the power spectrum of the CMB to much smaller scales (x3).
- It has higher sensitivity (x10).
- It observes in nine passbands rather than five with the goal of improving the astrophysical foreground models.
It is expected that most Planck measurements will be limited by how well foregrounds can be subtracted, rather than by the detector performance or length of the mission. This is particularly important for the polarization measurements. The dominant foreground depends on frequency, but examples include
synchrotron radiationSynchrotron radiation is electromagnetic radiation, similar to cyclotron radiation, but generated by the acceleration of ultrarelativistic charged particles through magnetic fields....
from the Milky Way at low frequencies, and dust at high frequencies.
Instruments
The spacecraft carries two instruments; the Low Frequency Instrument (LFI) and the High Frequency Instrument (HFI). Both instruments can detect both the total intensity and
polarizationPolarization is a property of waves that describes the orientation of their oscillations. This article primarily covers the polarization of electromagnetic waves such as light, although other types of wave also exhibit polarization....
of photons, and together cover a frequency range of 30 to 857 GHz. The cosmic microwave background spectrum peaks at a frequency of 160.2 GHz
Low Frequency Instrument
Frequency
(GHz) |
Bandwidth
|
Resolution
(arcmin) |
Sensitivity (total intensity)
, 14 month observation
(10−6) |
Sensitivity (polarization)
, 14 month observation
(10−6) |
| 30 |
0.2 |
33 |
2.0 |
2.8 |
| 44 |
0.2 |
24 |
2.7 |
3.9 |
| 70 |
0.2 |
14 |
4.7 |
6.7 |
The LFI has three frequency bands, covering the range of 30–70 GHz. The detectors use
High Electron Mobility TransistorsHigh Electron Mobility Transistors, also known as heterostructure FETs or modulation-doped FETs , are field effect transistors incorporating a junction between two materials with different band gaps as the channel instead of a doped region, as is generally the case for MOSFETs...
.
High Frequency Instrument
Frequency
(GHz) |
Bandwidth
|
Resolution
(arcmin) |
Sensitivity (total intensity)
, 14 month observation
(10−6) |
Sensitivity (polarization)
, 14 month observation
(10−6) |
| 100 |
0.33 |
10 |
2.5 |
4.0 |
| 143 |
0.33 |
7.1 |
2.2 |
4.2 |
| 217 |
0.33 |
5.5 |
4.8 |
9.8 |
| 353 |
0.33 |
5.0 |
14.7 |
29.8 |
| 545 |
0.33 |
5.0 |
147 |
N/A |
| 857 |
0.33 |
5.0 |
6700 |
N/A |
The HFI has six frequency bands, between 100 and 857 GHz. They use
bolometerA bolometer is a device for measuring the energy of incident electromagnetic radiation. It was invented in 1878 by the American astronomer Samuel Pierpont Langley....
s to detect photons. The four lower frequency bands have sensitivity to linear polarization; the two higher bands do not.
NASA
NASA played a role in the development of the mission and will contribute to the analysis of science data. Its
Jet Propulsion LaboratoryJet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is situated in the northern portion of Pasadena...
built components of the science instruments, including
bolometerA bolometer is a device for measuring the energy of incident electromagnetic radiation. It was invented in 1878 by the American astronomer Samuel Pierpont Langley....
s for the high-frequency instrument, a 20 Kelvin
cryocoolerCryocoolers are the devices used to reach cryogenic temperatures by cycling certain gases.A cryostat is likely to be used to reach and/or maintain similar conditions or keep some environment in cryogenic stasis.-See also:* Cryogenic processor...
for both the low- and high-frequency instruments, and amplifier technology for the low-frequency instrument.
Service Module – a common development for Herschel and Planck
A common
service moduleA service module is a spacecraft compartment containing a variety of support systems used for spacecraft operations. Usually located in the uninhabited area of the spacecraft, the service module is jettisoned upon the completion of the mission, and usually burns up during atmospheric reentry...
(SVM) was designed and built by
Thales Alenia SpaceThales Alenia Space is the company born after Thales had bought the participation of Alcatel in the two joint-ventures between Alcatel and Finmeccanica, Alcatel Alenia Space and Telespazio.-History:...
in its
TurinTurin is a major city as well as a business and cultural centre in northern Italy, capital of the Piedmont region, located mainly on the left bank of the Po River surrounded by the Alpine arch...
plant, for the Herschel and Planck missions combined into one single program .
Structurally the Herschel and Planck SVM's are very similar. Both SVM's are of octagonal shape and for both, each panel is dedicated to accommodate a designated set of warm units, while taking into account the dissipation requirements of the different warm units, of the instruments as well as the spacecraft.
Furthermore, on both spacecraft a common design for the
avionicsAvionics means "aviation electronics". It comprises electronic systems for use on aircraft, artificial satellites and spacecraft, comprising communications, navigation and the display and management of multiple systems...
, the attitude control and measurement system (ACMS) and the command and data management system (CDMS), and power subsystem and the tracking, telemetry and command subsystem (TT&C) has been achieved.
All spacecraft units on the SVM are redundant.
Power Subsystem
On each spacecraft, the power subsystem consists of the
solar arraySpacecraft operating in the inner solar system usually rely on the use of photovoltaic solar panels to derive electricity from sunlight. In the outer solar system, where the sunlight is too weak to produce sufficient power, radioisotope thermal generators are used as a power source.-History:The...
, employing triple-junction
solar cellA solar cell is a device that converts the energy of sunlight directly into electricity by the photovoltaic effect. Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the light source is...
s, a
batteryAn electrical battery is a combination of one or more electrochemical cells, used to convert stored chemical energy into electrical energy. Since the invention of the first Voltaic pile in 1800 by Alessandro Volta, the battery has become a common power source for many household and industrial...
and the power control unit (PCU). It is designed to interface with the 30 sections of each solar array, provide a regulated 28 V bus, distribute this power via protected outputs and to handle the battery charging and discharging.
For Planck, the circular solar array is fixed on the bottom part of the satellite, facing always the sun, as the satellite is spinning around its vertical axis.
Attitude and Orbit Control
This function is performed by the attitude control computer (ACC) which is the platform for the ACMS. It is designed to fulfil the pointing and slewing requirements of the Herschel and Planck payload.
The Planck satellite is
spunA rotation is a movement of an object in a circular motion. A two-dimensional object rotates around a center of rotation. A three-dimensional object rotates around a line called an axis. If the axis of rotation is within the body, the body is said to rotate upon itself, or spin—which implies...
at one revolution per minute, the absolute pointing error needs to be less than 37 arc min. For Planck being a survey platform, there is also a requirement to be met on pointing reproducibility error to be less than 2.5 arc min over 20 days.
The main sensor of the line of sight in both spacecraft is the star tracker.
Launch and orbit
The satellite was successfully launched, along with the
Herschel Space ObservatoryThe Herschel Space Observatory is a space observatory from the European Space Agency . It was originally proposed in 1982 by a consortium of European scientists...
, at 13:12:02 on 14 May 2009 aboard an
Ariane 5 ECAAriane 5 is a European expendable launch system designed to deliver payloads into geostationary transfer orbit or low Earth orbit. It is manufactured under the authority of the European Space Agency and the Centre National d'Etudes Spatiales , with EADS Astrium Space Transportation as prime...
heavy launch vehicle. The launch placed the craft into a very elliptical orbit (perigee: 270 km, apogee: more than 1,120,000 km), bringing it near the
Lagrangian pointThe Lagrangian points , are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects...
of the
Earth-Sun system, 1.5 million kilometers from the Earth.
The maneuver to inject Planck into its final orbit around was successfully completed on July 3, 2009, when it entered a
Lissajous orbitIn orbital mechanics, a Lissajous orbit is a quasi-periodic orbital trajectory that an object can follow around a Lagrangian point of a three-body system without requiring any propulsion. Lyapunov orbits around a libration point are curved paths that lie entirely in the plane of the two primary...
of 400,000 km radius around the Lagrangian point. The temperature of the High Frequency Instrument reached just a tenth of a degree above absolute zero (0.1 K) on July 3, 2009, placing both the Low Frequency and High Frequency Instruments within their cryogenic operational parameters, making Planck fully operational.
Results
On September 2009,
ESA|owner = |headquarters = Paris|spaceport = Guiana Space Centre|image = ESA LOGO.svg|size = 240px|acronym = ESA|established = 1975|administrator = Jean-Jacques Dordain...
announced the preliminary results from the
Planck First Light Survey (performed to demonstrate the stability of the instruments and the ability to calibrate them over long periods). This results indicate that the data quality is excellent.
The final results (with all processed data) are expected to be delivered to the worldwide community towards the end of 2012.
See also
- Cosmic microwave background experiments
There have been a variety of experiments to measure the Cosmic microwave background radiation anisotropies and polarization since its first observation in 1964 by Penzias and Wilson. These include a mix of ground-, balloon- and space-based receivers...
- Observational cosmology
Observational cosmology is the study of the structure, the evolution and the origin of the universe through observation, using instruments such as telescopes and cosmic ray detectors.-Early observations:...
- Herschel Space Observatory
The Herschel Space Observatory is a space observatory from the European Space Agency . It was originally proposed in 1982 by a consortium of European scientists...
External links