ESA's mission to study the very early Universe – Planck – has successfully completed its test survey of the sky.

The microwave observatory launched in May and is the first European mission designed to study the relic radiation from the big bang, known as the Cosmic Microwave Background (CMB). Planck's detectors are cooled to temperatures that are approaching absolute zero in order to seek out tiny variations in the temperature of the CMB that are about a million times smaller than one degree.

The first light survey began on 13 August and spanned two weeks, during which Planck soaked up radiation from a strip of sky in nine frequencies. This allowed the observatory to separate the CMB from light emitted by the Galaxy at the same frequencies. As a result, the mission will also provide unprecedented observations of our own Galaxy.

"We are thrilled that Planck is working so well," says Professor George Efstathiou of the University of Cambridge and UK Principal Investigator for Planck. "We have now begun scientific analysis of the beautiful data from Planck and are looking forward to finding out new information on the beginnings of space and time as we know it."

Each map completed for each frequency is a ring about 15 degrees wide, stretching across the full sky. "In the 16 years since Planck’s development started, this is the most exciting time," says Professor Richard Davis of Manchester University and principal investigator of Planck’s UK-built LFI instrument. "The wonderful thing is that Planck from its vantage point one million miles from Earth is now producing images of the creation of the Universe, the so-called big bang, with a clarity never seen by mankind."

Planck is now working towards its first all-sky map, which is expected to be completed in around six months. With its 15 month life expectancy, Planck will be able to gather data for two full independent all-sky maps that are set to keep cosmologists and astrophysicists busy for decades to come.