Monday, March 15, 2004
Sky's the limit for this science lesson
MIKE WENDLAND: There are balloons and there are tetroons.
Tetroons are balloons shaped like tetrahedrons. That's the geometric term for a three-dimensional shape that has four sides.
"Think of a diamond in the sky," says Robert Rochte.
Rochte, director of technology at the Grosse Pointe Academy, and his eager third-grade students hope to see a tetroon within the next month, depending on the sun and wind conditions, when they launch the fifth in a series of experimental balloons from Grosse Pointe Farms in an effort to learn about weather, navigation and electronics.
They're also having fun.
These tetroon balloons are made of high-density polyethylene, about 30 feet high. Although Rochte and his students use a leaf blower to inflate them, the sun is what causes them to rise, heating the air contained in the envelope.
SD4 -- for Sky Diamond No. 4 -- was launched Feb. 16 around 9:30 a.m. Nearly 11 hours later, it had traveled 563 miles to Peterborough, N.H., where, after a setting sun rapidly cooled the envelope of air inside the balloon, it rapidly descended into the branches of a 40-foot tree in the middle of a forest.
It set a third-place record for flight duration, missing the 15-hour mark set last October in Portugal.
Rochte got into solar-heated balloons through his longtime ham radio hobby. The balloons all carry an Amateur Radio Automatic Reporting System payload that consists of a low-powered handheld radio, a small Global Positioning Satellite tracking device and an antenna that allows Rochte's team to monitor the flight's progress.
Last month's flight was not without some excitement. For the first nine hours, all was well, with a steady modem-like sound being received back at Rochte's house in Warren.
"We watched it climb over Lake St. Clair, into Canada, the northern tip of Lake Erie, on into New York," he recalls. "And then, about 6:15 p.m. as it was about 12 miles up, above the jet stream, we lost contact."
With no signal, there was no way to know where the balloon -- traveling at speeds up to 116 m.p.h. -- would go. And without finding its place of descent, there would likely be no recovery of the radio and GPS gear that Rochte spent about $300 of his own money to buy.
About 2 p.m. that next day, the signals suddenly returned. Rochte showed his students how to read the GPS coordinates. From there, they went to a Web site, www.Findu.com, which monitors GPS signals used on the VHF ham frequencies and superimposes the location on a map.
He then located a ham radio operator in Peterborough who agreed to go out and look for the balloon.
That was last month. Now a new balloon is getting ready to soar: SD5, which was being tested this week inside the fieldhouse at the academy.
"This is a great learning opportunity for the students," said Rochte. "When you learn science and math and physics hands-on at such an early age, it sticks with them and gets them excited about maybe pursuing science as a career."
Or, put another way, launching tetroons after school is sure a lot more engaging than going home to watch reruns of cartoons, as some of the kids used to do.
Onward and upward, Mr. Rochte.
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