The European Space Agency's (ESA) Planck satellite and the ground-based BICEP2 and Keck Array experiments found no conclusive evidence of primordial gravitational waves despite an earlier detection.

The satellite's work with ground-based telescopes shows that interstellar dust was actually the cause of more than half of the signal detection announced almost a year ago.

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Astronomers are searching for a particular signature of cosmic "inflation"-- a very brief accelerated expansion the universe experienced when it was only the tiniest fraction of a second old.

Gravitational waves or tiny perturbations in the fabric of space-time astronomers believe would have been generated during the inflationary phase.

ESA scientists said data from the agency's Planck space observatory revealed interstellar dust caused more than half of the signals detected by the Antarctica-based BICEP2 experiment. The Planck spacecraft observations weren't available last March when the BICEP2 science team made its announcement.

"Unfortunately, we have not been able to confirm that the signal is an imprint of cosmic inflation," said Jean-Loup Puget, principal investigator of the HFI instrument on Planck at the Institut d'Astrophysique Spatiale in Orsay, France.

The conclusion is the result of a collaborative analysis by scientists with both BICEP2 and Planck, using data from both telescopes and the Keck array at the South Pole.

The Planck and BICEP2 teams joined forces, combining the satellite's ability to deal with foregrounds using observations at several frequencies with the greater sensitivity of ground-based experiments over limited areas of the sky, thanks to their more recent, improved technology.

"This analysis shows that the amount of gravitational waves can probably be no more than about half the observed signal," says Clem Pryke, a principal investigator of BICEP2 at the University of Minnesota.

Tagscosmic inflation, gravitational force, space exploration, dust, ESA, Big Bang Theory