The aim of the Planck mission was to map the Cosmic Microwave Background to unprecedented accuracy and resolution in order to understand the mechanisms that gave rise to the structure we observe today in the Universe. RHEA was involved in the mission from 2004, contributing to both the development and operations phases.

Planck mission timescale

Mission launch: 14 May 2009
Survey operations: 12 August 2009 to 13 January 2010 (HFI); 13 October 2013 (LFI)
End of operations: 23 October 2013

About the Planck mission

Planck was a European survey mission. Its scientific payload, provided by a European consortium of universities and industry, consisted of two instruments:

  • High Frequency Instrument (HFI) – a set of bolometers (very accurate thermometers) covering a range of frequencies from 100GHz to 857GHz, operating at a temperature of 0.1K.
  • Low Frequency Instrument (LFI) – a set of radiometers (radio receivers) at 30GHz, 44GHz and 70GHz.

Several of the channels in both instruments could also measure polarization.

The range of frequencies covered by both instruments ensured the astrophysical foregrounds could be identified, studied and removed from the data, so that the Cosmic Microwave Background signal (a faint glow of the hot beginning of the Universe left in space by the Big Bang) could be studied on its own.

Planck’s main technical achievements

Planck’s cooling chain was probably the most complex ever designed for a space mission. The temperature of the HFI was lowered to 100mK to reduce the noise in the instrument. This required three coolers to bring the different stages of both instruments to 20K, then 4K and finally 100mK.

A failure in one of the coolers would have compromised the entire mission. An extensive development and testing campaign was therefore put in place to guarantee that once in space, the instruments would reach the required temperatures without a single failure.

Planck’s main scientific achievements

The Planck mission resulted in the most accurate ever temperature maps of the entire sky and the first ever maps of polarization covering the entire sky.

These and many other products allowed scientists to make the most precise measurement so far of the expansion rate of the universe and estimate the Dark Matter and Dark Energy content of the Universe.

Strange but true

The HFI operated at 100mK. This meant that during its operations, it was the coldest object in the Universe.

How RHEA is contributing to the Planck mission

Our primary contribution was providing two support scientists to the Planck Science Office (PSO) from 2004: the Planck HFI Support Scientist and the Planck LFI Support Scientist.

Their main responsibilities during the development phase were:

  • instrument development and ground testing campaigns
  • data analysis software development
  • elaboration of the in-orbit testing plan for the scientific payload.

And then during operations:

  • coordinating scientific operations of the Planck instruments
  • designing, planning and executing the Planck observation strategy
  • creating and updating the specifications of the Planck Legacy Archive (PLA) developed by the Science Archives Team at ESAC
  • testing and operating the PLA.

In addition, our MOIS tool suite was used for operations preparations.

Main image: Planck and the Cosmic microwave background. © ESA and the Planck Collaboration – D. Ducros

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