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Temperature loggers survive bomb-squad blasts

ControlDesign.com
04/04/2007

Over Thanksgiving weekend last year, Dr. Anne Jefferson, a research associate studying hydrology in the Department of Geosciences at Oregon State University, put data loggers she had been using in the trunk of her rental car. She subsequently forgot to remove them when she returned the car to the airport. When she and her husband arrived back in Oregon, they found federal agents waiting for them at the gate.

A rental car company employee had become suspicious of the five, foot-long PVC pipes filled with gravel that he found in the car’s trunk. The pipes each contained three battery-powered underwater temperature-monitoring devices, which are slightly larger than bottle caps and have blinking LED lights. Jefferson used the devices to collect water-temperature data in stream channels along the Mississippi River.

Airport police and the FBI’s bomb squad were called in. When bomb-sniffing dogs turned up nothing, the squad removed the pipes from the trunk and used a high-pressure stream of water to “detonate” them. Nothing exploded, but the pipes were reduced to bits of plastic pipe and gravel.

After confirming her story with airport officials in Oregon, and believing her five months of data to be destroyed, Jefferson later received word from the Minneapolis airport that some of the loggers still were intact.

When Onset Computer Corp., the manufacturer of the data loggers, heard the story, it contacted Jefferson, and offered to try to retrieve the data.

Two weeks after the incident, Jefferson received all the loggers in a sealed police evidence bag. Of the fifteen battered devices, Jefferson was able to download data from all but a few. She sent the remaining two loggers to Onset, where engineers were able to recover the rest of the data. “Having this temperature data is a tremendous relief. The data is the study, the basis for my postdoctoral research,” said Jefferson, “and, without it, there was going to be a problem.”

Onset says the devices, known as TidbiTs, are designed to be submerged underwater and withstand rough conditions. The data recorded by the device is stored electronically in EEPROM, which unlike RAM, retains data even when the power supply is cut off.

Jefferson hasn’t tried to fly anywhere, or rent a car, since the incident. “We’re probably on their blacklist,” she said.