New Brunswick amateur radio operators are on the lookout for a high-altitude balloon believed to have come down somewhere in the Maritimes, after being launched as an experiment by a Michigan Grade 5 class.

Even though his balloon has disappeared, Michigan teacher Robert Rochte says its mission has been a success.

"This would actually be our farthest flight so far," he said.

The balloon, carrying a small Styrofoam cooler containing a circuit board, ham radio transmitter and a Global Positioning System, was launched Thursday.

It was designed to travel at 10,000 metres on the jet stream signalling its exact position every two minutes along the way. But the GPS failed, and the last reported signals were in Morse code, picked up by ham radio towers in the Maritimes, one in Scotch Mountain, near Sussex, N.B., and one in Truro, N.S.

Greg Dentremont with the Loyalist City Radio Club in Saint John, which owns the Scotch Mountain tower, says the balloon could be in the Alma-Fundy Park area, if not lost in the Bay of Fundy or somewhere in Nova Scotia.

Rochte says if anyone finds the balloon, he'd like to have it back. He says the balloon itself is almost clear, the cooler is wrapped with duct tape and the parachute on the contraption is yellow and purple coloured and about 60 centimetres in diameter.

He says his students will reuse the radio equipment if it is found. They plan to launch a second balloon this spring.