Planck first light yields promising results

ESA's Planck microwave observatory - the first European mission designed to study the Cosmic Microwave Background, the relic radiation from the Big Bang - started regularly surveying the sky from its vantage point at L2 on 13 August 2009.

Prior to this the two instruments of this modern day 'time machine' had been fine-tuned for optimum performance. Both instruments have demonstrated excellent characteristics so far, fulfilling expectations from ground tests. In preparation for routine scientific operations, their long-term stability has been verified by conducting a first 'trial' survey - the First Light Survey.

Planck's instruments provide key data for cosmology theories

Observing at microwave wavelengths, the satellite rotates around its axis, surveying the entire sky over time and in the process measuring tiny fluctuations in the temperature of the Cosmic Microwave Background (CMB).

Equipped with two powerful instruments, the Low Frequency Instrument (LFI) and the High Frequency Instrument (HFI), Planck will collect data continuously during a period of at least 15 months. The data will provide important constraints on theories that describe the infancy and evolution of the Universe.

Following launch on 14 May 2009, check-outs of the satellite's subsystems were started in parallel with the cool-down of the instruments' detectors. The detectors are looking for variations in the temperature of the CMB that are about a million times smaller than one degree - a feat comparable to measuring from Earth the body heat of a rabbit sitting on the Moon. To achieve this, Planck's detectors must be cooled to extremely low temperatures, some very close to absolute zero (-273.15°C, or 0 K).

With check-outs of the subsystems finished, instrument commissioning, optimisation, and initial calibration were completed by the second week of August.

The false-colour strip superimposed on an optical map of the Milky Way indicates the region of the Planck First Light Survey. Credit: ESA, LFI & HFI Consortia (Planck), Background image: Axel Mellinger




This mosaic of maps zooms in on a small part (20°x20°) of the First Light Survey, in which our own Milky Way shines very brightly. Credit: ESA, LFI & HFI Consortia (Planck)




A zoom in on an approximately 10°x10° region of the First Light Survey where the Milky Way is not the predominant signal shows clearly the features which are of most interest to Planck, i.e. the Cosmic Microwave Background. Credit: ESA, LFI & HFI Consortia (Planck)

First Light Survey complete

The First Light Survey, which began on 13 August 2009, covers a two-week period during which Planck surveyed the sky continuously. It was carried out to verify the stability of the instruments and the ability to calibrate them over long periods to the exquisite accuracy needed.

The First Light Survey was completed on 27 August, yielding maps of a strip of the sky, one for each of Planck's nine frequencies. Each map is a ring about 15 degrees wide, stretching across the full sky. Preliminary analysis indicates that the quality of the data is excellent.

Routine operations are now underway

Routine operations started as soon as the First Light Survey was completed, and surveying will now continue for at least 15 months without a break. In approximately 6 months time, the first all-sky map will be assembled.

Within its allotted operational life of 15 months, Planck will be able to gather data for two full, independent all-sky maps. However, in order to fully exploit the high sensitivity of Planck, the data will require a great deal of delicate adjustments and careful analysis. About two years will be needed to fully process the data and to extract the main scientific results. The processed data will then be delivered to the worldwide community towards the end of 2012. It promises to contain a treasure trove of data that will keep both cosmologists and astrophysicists busy for decades to come.

Source: European Space Agency
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