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Planck mission graphic

Phase: Operating

Launch Date: May 14, 2009

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Program(s):Physics of the Cosmos

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The Planck mission will address some of the most fundamental questions in cosmology and astrophysics. It will tell us about the geometry and contents of the universe, how the universe grew immediately after its birth, and how the stage was set for the universe to evolve into structures that we see today, such as galaxies.

Like its predecessor, NASA’s Wilkinson Microwave Anistropy Probe (WMAP), Planck is designed to achieve these goals by making a careful measurement of the Cosmic Microwave Background (CMB), the remnant background radiation left over from the Big Bang. The CMB is remarkably uniform over the entire sky, with an effective current temperature of 2.7 degrees Kelvin. But the CMB is not completely smooth-- there exist fluctuations in temperature at the tiny level of one part per 100,000. Tiny as they are, it is from these very fluctuations that grew the current large-scale structures of the universe.

Planck will image these tiny fluctuations in the CMB over the whole sky with unprecedented sensitivity and angular resolution. It will resolve structures down to 5 arcminutes in angular size on the sky, and will be able to detect temperature variations at the microKelvin level. Planck will also be able to measure the polarization of the CMB radiation, which tells us about the early history of star formation.

The Planck mission will collect and characterize radiation from the Cosmic Microwave Background (CMB) using sensitive microwave receivers operating at extremely low temperatures. The Planck spacecraft is 4.2 meters high and has a maximum diameter of 4.2 meters, with a launch mass of around 1.8 tons. The two scientific instruments in Planck are:

  • The LFI (Low Frequency Instrument), an array of coherent microwave receivers based high electron mobility transistor amplification.  
  • The HFI (High Frequency Instrument), an array of microwave detectors using bolometers equipped with neutron transmutation doped germanium thermistors.

Planck is an ESA-led mission with substantial contributions from NASA.  For reasons of cost effectiveness, ESA launched Planck together with Herschel, an infrared space telescope, on an Ariane-5 launch vehicle on May 14, 2009. The two spacecraft separated soon after launch and will operate independently.


Focus Areas for PlanckBig Questions for Planck Related Links
  • ESA Planck Website -
  • Science@ESA - Planck video -