Hunting for gravity

SPACECRAFT Cassini will spend the next 40 days hunting for gravitational
waves as it cruises past Earth on its seven-year trip to Saturn. Gravity waves
are slight ripples in the space-time fabric of the Universe, created by massive
bodies such as black holes. Einstein predicted them, but they’ve never been
detected directly. Three Earth-based stations will try to spot tiny fluctuations
in Cassini’s speed as gravity waves stretch and compress space. It’s a long
shot, says John Armstrong of NASA’s Jet Propulsion Laboratory. “But if you don’t
look, you won’t see anything.”