Product Code Database
Planck was a space observatory operated by the European Space Agency (ESA) from 2009 to 2013. The project aimed to map the anisotropies of the cosmic microwave background (CMB) at microwave and infrared frequencies, with high sensitivity and angular resolution. The mission provided data that substantially improved upon previous observations made by the NASA Wilkinson Microwave Anisotropy Probe (WMAP).
The Planck observatory was a major source of information relevant to several cosmological and astrophysical issues. One of its key objectives was to test cosmological theories about the early Universe, its composition and evolution, and the origin of cosmic structure.
Planck was initially called COBRAS/SAMBA, which stands for the Cosmic Background Radiation Anisotropy Satellite/Satellite for Measurement of Background Anisotropies. The project started in 1996, and it was later renamed in honor of the German physicist Max Planck (1858–1947), who is widely regarded as the originator of quantum theory by deriving the formula for black-body radiation.
Built at the Cannes Mandelieu Space Center by Thales Alenia Space, Planck was created as a medium-sized mission for ESA's Horizon 2000 long-term scientific program. The observatory was launched in May 2009 and reached the Earth/Sun L2 point by July 2009. By February 2010, it had successfully started a second all-sky survey.
On 21 March 2013, the Planck team released its first all-sky map of the cosmic microwave background. The map allowed researchers to measure temperature variations in the CMB with the highest accuracy then available. In February 2015, an expanded release was published, which included polarization data. The final papers by the Planck team were released in July 2018, marking the end of the mission.
At the end of its mission, Planck was put into a heliocentric graveyard orbit and passivated to prevent it from endangering any future missions. The final deactivation command was sent to Planck in October 2013.
The mission provided the most precise measurements of several key cosmological parameters. Planck's observations helped determine the age of the universe, the average density of ordinary matter and dark matter in the Universe, and other important characteristics of the cosmos.
Planck had a higher resolution and sensitivity than WMAP, allowing it to probe the power spectrum of the CMB to much smaller scales (×3). It also observed in nine frequency bands rather than WMAP's five, with the goal of improving the astrophysical foreground models.
It is expected that most Planck measurements have been limited by how well foregrounds can be subtracted, rather than by the detector performance or length of the mission, a particularly important factor for the polarization measurements. The dominant foreground radiation depends on frequency, but could include synchrotron radiation from the Milky Way at low frequencies, and dust at high frequencies.
Planck passive and active cooling systems allow its instruments to maintain a temperature of , or 0.1 °C above absolute zero. From August 2009, Planck was the coldest known object in space, until its active coolant supply was exhausted in January 2012.
NASA played a role in the development of this mission and contributes to the analysis of scientific data. Its Jet Propulsion Laboratory built components of the science instruments, including for the high-frequency instrument, a 20-kelvin cryocooler for both the low- and high-frequency instruments, and amplifier technology for the low-frequency instrument.
| 2.8 |
| 3.9 |
| 6.7 |
The LFI has three frequency bands, covering the range of 30–70 GHz, covering the microwave to infrared regions of the electromagnetic spectrum. The detectors use high-electron-mobility transistors.
| 4.0 |
| 4.2 |
| 9.8 |
| 29.8 |
| N/A |
| N/A |
The HFI was sensitive between 100 and 857 GHz, using 52 bolometer detectors, manufactured by JPL/Caltech, optically coupled to the telescope through cold optics, manufactured by Cardiff University's School of Physics and Astronomy, consisting of a triple horn configuration and optical filters, a similar concept to that used in the Archeops balloon-borne experiment. These detection assemblies are divided into 6 frequency bands (centred at 100, 143, 217, 353, 545 and 857 GHz), each with a bandwidth of 33%. Of these six bands, only the lower four have the capability to measure the polarisation of incoming radiation; the two higher bands do not.
On 13 January 2012, it was reported that the on-board supply of helium-3 used in Planck dilution refrigerator had been exhausted, and that the HFI would become unusable within a few days. By this date, Planck had completed five full scans of the CMB, exceeding its target of two. The LFI (cooled by helium-4) was expected to remain operational for another six to nine months.
The overall cost is estimated to be for the Planck and for the Herschel mission. Both figures include their mission's spacecraft and payload, (shared) launch and mission expenses, and science operations.
Structurally, the Herschel and Planck SVMs are very similar. Both SVMs are octagonal in shape and 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. On both spacecraft, a common design was used for the avionics, attitude control and measurement (ACMS), command and data management (CDMS), power, and tracking, telemetry and command (TT&C) subsystems. All units on the SVM are redundant.
For Planck, the circular solar array is fixed on the bottom of the satellite, always facing the Sun as the satellite rotates on its vertical axis.
The Planck satellite Rotation at one revolution per minute, with an aim of an absolute pointing error less than 37 arc-minutes. As Planck is also a survey platform, there is the additional requirement for pointing reproducibility error less than 2.5 arc-minutes over 20 days.
The main line-of-sight sensor in both Herschel and Planck is the star tracker.
The manoeuvre to inject Planck into its final orbit around was successfully completed on 3 July 2009, when it entered a Lissajous orbit with a radius around the Lagrangian point. The temperature of the High Frequency Instrument reached just a tenth of a degree above absolute zero (0.1 kelvin) on 3 July 2009, placing both the Low Frequency and High Frequency Instruments within their cryogenic operational parameters, making Planck fully operational.
On 15 January 2010 the mission was extended by 12 months, with observation continuing until at least the end of 2011. After the successful conclusion of the First Survey, the spacecraft started its Second All Sky Survey on 14 February 2010. The last observations for the Second All Sky Survey were made on 28 May 2010.
Some planned pointing list data from 2009 has been released publicly, along with a video visualization of the surveyed sky.
On 17 March 2010, the first Planck photos were published, showing dust concentration within 500 light years from the Sun.
On 5 July 2010, the Planck mission delivered its first all-sky image.
The first public scientific result of Planck is the Early-Release Compact-Source Catalogue, released during the January 2011 Planck conference in Paris.
On 5 May 2014 a map of the galaxy's magnetic field created using Planck was published.
The Planck team and principal investigators Nazzareno Mandolesi and Jean-Loup Puget shared the 2018 Gruber Prize in Cosmology. Puget was also awarded the 2018 Shaw Prize in Astronomy.
| + Lambda-CDM model from 2013 Planck results
! Parameter !! Symbol !! Planck Best fit !! Planck 68% limits !! Planck+lensing Best fit !! Planck+lensing 68% limits !! Planck+WMAP Best fit !! Planck+WP 68% limits !! Planck+WP +HighL Best fit !! Planck+WP +HighL 68% limits !! Planck+lensing +WP+highL Best fit !! Planck+lensing +WP+highL 68% limits !! Planck+WP +highL+BAO Best fit !! Planck+WP +highL+BAO 68% limits |
Project scientists worked too with BICEP2 scientists to release joint research in 2015 answering whether a signal detected by BICEP2 was evidence of primordial gravitational waves, or was simple background noise from dust in the Milky Way galaxy. Their results suggest the latter.
| + Lambda-CDM model from 2015 Planck results
! Parameter !! Symbol !! TT+lowP 68% limits !! TT+lowP +lensing 68% limits !! TT+lowP +lensing+ext 68% limits !! TT,TE,EE+lowP 68% limits !! TT,TE,EE+lowP +lensing 68% limits !! TT,TE,EE+lowP +lensing+ext 68% limits |
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| + Lambda-CDM model from 2018 Planck results
! Parameter !! Symbol !! TT+lowE 68% limits !! TE+lowE 68% limits !! EE+lowE 68% limits !! TT,TE,EE+lowE 68% limits !! TT,TE,EE+lowE +lensing 68% limits !! TT,TE,EE+lowE +lensing+BAO 68% limits | ||
| 0.02242±0.00014 | ||
| 0.11933±0.00091 | ||
| 1.04077±0.00047 | 1.04101±0.00029 | |
| 0.0561±0.0071 | ||
| 3.047±0.014 | ||
| 0.9665±0.0038 | ||
| 67.66±0.42 | ||
| 0.6889±0.0056 | ||
| 0.3111±0.0056 | ||
| 0.825±0.011 | ||
| 7.82±0.71 | ||
| 13.787±0.020 | ||
| 1089.80±0.21 | ||
| Comoving size of the sound horizon at z = z*(Mpc) | 144.57±0.22 | |
| 1.04119±0.00029 | ||
| 1060.01±0.29 | ||
| 147.21±0.23 | ||
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