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Planck 'time machine' to be switched off at last

Paul Sutherland, Feature writer
Oct 20, 2013, 23:00 UTC

Sen—One of world’s most successful orbiting observatories will finally be switched off this week after collecting valuable evidence on how the Universe evolved.

How the Universe began is one of the great challenges of cosmology. The European Space Agency’s Planck space telescope has allowed astronomers to pin down its beginnings in the Big Bang to a date 13.8 billion years ago.

Since 2009, Planck has been a major tool in helping astronomers peer back in time to discover what happened since that momentous event to build the structure of the cosmos that we see around us today.

But after four and a half years of scanning the heavens, this powerful instrument is finally being shut down, its mission over. On Saturday, 19 October, the probe’s Low Frequency Instrument was switched off, having completed work on 3 October.

Planck’s High Frequency Instrument already ended its observations in January 2012, after a total of five all-sky surveys had been completed with both instruments. Following some final operational procedures, the spacecraft will be switched off completely on Wednesday, 23 October.

In the middle of the last century, cosmologists realised that there would be a background glow left over from the Big Bang. It was detected for real in the 1960s with a radio antenna after scientists ruled out roosting pigeons as the cause of a mysterious hiss.

Impression of Planck in spaceAn impression of the Planck space telescope at work. Credit: ESA

This ancient echo, dubbed the Cosmic Microwave Background (CMB), was later mapped in more detail, first by NASA’s Cosmic Background Explorer (COBE) in the early 1990s, then by the agency’s Wilkinson Microwave Anisotropy Probe (WMAP) in the early years of this century.

Planck followed up by delivering the most detailed picture yet of the leftover radiation from the Big Bang that was imprinted on the sky when the Universe was only 380,000 years old.

The CMB is the most accurate snapshot of how matter was distributed in the early Universe. It shows tiny fluctuations in temperature that correspond to regions of slightly different densities at very early times, representing the seeds of all future structure, the stars and galaxies of today.

Jan Tauber, ESA’s Planck project scientist, said: “Planck has delivered the most precise all-sky image of the CMB that is enabling us to test a huge variety of models of the origin and evolution of the cosmos.

An ESA video describes Planck's amazing achievements. Credit: ESA

“But long and meticulous work was required before we could start exploiting this wealth of cosmological information, since the CMB is hidden behind foreground glare including emissions from material within our own Galaxy, as well as from other galaxies and galaxy clusters.”

Planck’s observations were not limited to the distant background. It also gained valuable new data on the foreground objects such as mentioned by Tauber. It provided the most extensive catalogue ever of the largest galaxy clusters that are the most massive building blocks in the Universe. And it identified the densest and coldest clumps of matter within our Milky Way, from which new stars may form in future.

Other results included redefining the relative proportions of the ingredients that make up the Universe. Normal matter, as found in stars and galaxies, makes up just 4.9 per cent, invisible dark matter makes up 26.8 per cent and the mysterious force dark energy, believed to drive the expansion of the Universe, 68.3 per cent.

Planck’s results also allowed astronomers to derive a new age for the Universe, now set at 13.8 billion years.