Scientific tests have solved the mystery of the basketball-size chunk of green ice that fell Chicken Little-style onto an Eastern Shore trailer park last month.

The heated debate over the frozen green blob from the blue had focused on whether the chunk was an ice meteor or merely frozen refuse from an airplane's leaky lavatory.

Chemical analyses conducted at the University of Maryland and the University of Pennsylvania have yielded identical results supporting the more mundane explanation.

The melted remains of the ice, according to John Lutz, an amateur investigator of bizarre phenomena who commissioned the tests, were definitely of earthly origin -- a sanitizing agent combined with urine.

"It looks like it was from a passing plane after all," said Lutz, who had backed the ice meteor theory.

Lutz said he had informed the Maryland police trooper, who responded to the call about the ice chunk and was saving part of the sample in a mayonnaise jar.

Fred Farrar of the Federal Aviation Administration, which had been investigating the incident, said the agency had had no luck uncovering the leaking culprit. He said the ice chunks form when there is an outside leak in the holding tank used to store refuse from airplane toilets. The leaked liquid freezes at high altitudes and is shaken off by the plane's vibrations. It falls of its own weight, or comes unglued at lower altitudes.

Meanwhile, Lutz is looking into another ice chunk, two feet across, that fell Sept. 23 in Perryman, Md.

Whether from ice meteors or airplanes, Lutz said, "these things are dropping out of the sky like hotcakes."