By Bob Holmes NO ONE can accuse H. Norman Abramson of sitting in an ivory tower. “It is common everyday knowledge to each of us that any small container filled with liquid must be moved or carried very carefully to avoid spills,” the US engineer and fluid dynamicist wrote almost half a century ago. “Experience has taught us that the unrestrained free surface of the liquid has an alarming propensity to undergo rather large excursions, for even very small motions of the container.” Hardly rocket science, you might think. The irony is, it was. Abramson’s words come from the introduction to a 464-page report he wrote for NASA in 1966. At the time, the US space agency was aiming to catapult astronauts to the moon atop rockets filled with liquid propellants. Abramson’s magnum opus, entitled The Dynamic Behavior of Liquids in Moving Containers with Applications to Space Vehicle Technology, presented the sum of human knowledge on a phenomenon of life-or-death importance to the space race: sloshing. It is a problem even now. Fuel sloshing has probably caused the failure of several rocket launches, and in 1998 a slosh-induced tumble cut short a course adjustment and set back by a year the Near Earth Asteroid Rendezvous (NEAR) mission to the asteroid 433 Eros. In 2005, the European Space Agency launched an entire mission, dubbed Sloshsat, to study fluid dynamics in microgravity. NASA’s own investigations continue. Back on Earth, we are still baffled by the burning question Abramson touched on. Why does hot coffee leap from its cup so readily, and can we do anything about it?