As comet nears Sun, scientists await its secrets

A comet streaking through space with a European robot lab riding piggyback will skirt the Sun this week in another landmark in the extraordinary quest to unravel the mystery of Earth life.

Scientists hope the increased heat at perihelion - the point at which the comet is closest to the Sun - will cause the enigmatic traveler to shed more of its icy crust.

If so, they believe it could spew out pristine particles, leftovers from the solar system's birth 4.6 billion years ago.