A space telescope designed to peer into the enigma of the "Big Bang" has served up its first overall image of the cosmos, the European Space Agency said on Monday.

The picture "is an extraordinary treasure chest of new data for astronomers," ESA declared.

The image was painstakingly built up, slice by slice, by a 700-million-euro (875-million-dollar) telescope, Planck, which ESA put in orbit in May last year.

Planck is designed to look at radiation in the microwave part of the energy spectrum.

Microwave signatures point to the birth and death of stars and galaxies, as well as the embers of the "Big Bang" which, according to theory, brought the Universe into existence 13.7 billion years ago.

This primeval energy, known as cosmic microwave background radiation (CMBR), washes across the sky.

But in order to spot it in Planck's first "all-sky" image, scientists will have to filter out background noise from our own galaxy, the Milky Way, ESA said.

"We are opening the door to an Eldorado where scientists can seek the nuggets that will lead to deeper understanding of how our Universe came to be and how it works now," said David Southwood, ESA's director of science and robotic exploration.

"The image itself and its remarkable quality is a tribute to the engineers who built and have operated Planck. Now the scientific harvest must begin."

Named after the 20th-century German physicist Max Planck who founded quantum theory, the mission is equipped with a 1.5-metre (4.8-feet) telescope that focuses radiation onto two arrays of microwave detectors, each cooled to almost absolute zero.

By the end of its mission in 2012, Planck should have completed four all-sky scans, ESA said. The data release of the CMBR -- in essence a map of the Big Bang -- is also scheduled for 2012.