CAMBRIDGE, Sept 7: The first detailed analysis from a US mission that smashed a hole in a comet suggests these wanderers are fragile agglomerations of dust, laced with carbon molecules that some theorists say sowed the seeds for life on Earth.

Until now, comets have been dubbed “dirty snowballs”, but Nasa’s Chief Scientist Michael A’Hearne said it might be appropriate to call them “snowy dirtballs” given the extraordinary dominance of ultrafine dust.

“It’s like a brittle sponge... which crumbles in your hand,” said Uwe Keller, a scientist with the European Space Agency’s comet-chasing probe Rosetta, which turned its own eyes on the collision on July 14 to add to the data flow.

Scientists who staged the Deep Impact mission, which climaxed on July 4 when a projectile the size of a washing machine whacked into Comet Tempel 1, said on Tuesday that the data stirred both quiet satisfaction and amazement.

They said some long-standing hypotheses about comets have been given the comfort of evidence — but others have been swept away.

Chemical analysis from the plume of dust and gas that spewed from the impact showed largely predicted volumes of silicates.

Michael A’Hearne, presenting the research on the sidelines of a meeting of US and European astronomers, said this discovery buttressed a contested theory about the origins of life.

Under the “pan-spermia” idea, comets pounded the early Earth billions of years ago, bringing the planet organic molecules that reacted with light and heat from the sun, eventually providing the rich chemical soup from which all life began.

“I would argue that it (the pan-spermia theory) is (now) more likely, just because we have seen this big enhancement in organic materials coming out,” A’Hearne told a teleconference.

Early analysis suggested comets were rich in carbon dioxide, acetylene, ammonium and hydrogen cyanide, and a wider range of carbon molecules was likely to be found as scrutiny of the data progressed, he said.—AFP