Iridium Satellite, in conjunction with its service provider Marlink, is providing two-way data communications with a remote unmanned buoy measuring ice thickness in the Arctic Ocean as part of a program aimed at detecting climate change at high latitudes. The Sea Ice Thickness Observation System (SITHOS) was developed by Christian Michelson Research (CMR), a Norwegian scientific research organization. It was deployed in late 2005 at 84 degrees north and 60 degrees west.
The buoy contains sophisticated two-axis tilt sensors that measure the resonant frequency of deep-water waves under the ice. These waves are typically 300 meters long and only one millimeter deep. The raw tilt-meter data is transmitted at intervals through the Iridium satellite network. The buoy acquires and transmits up to five hours of data for each measurement. By analyzing the movement of the deep-water waves, scientists can make accurate estimates of the thickness of the ice at the surface.
The SITHOS buoy, encased in a hardened ruggedized capsule, was designed to be deployed by parachute, permitting it to be placed in locations that cannot easily be reached over the ice.
“Satellite communications is the only viable means of transmitting data from the Arctic buoys to locations hundreds of miles away,” said Soren Einshoj, managing director of Marlink. “After studying the communications requirements of the SITHOS, we concluded that Iridium’s constellation of low-flying satellites, with their orbits intersecting over the poles, is the ideal solution for this challenging application.”
“Since Iridium provides two-way data communications, we can set and change buoy parameters remotely at any time,” said David Peddie, scientist of CMR Instrumentation. “Log rate, acquisition time, sample period and many other parameters can be easily changed using e-mail to achieve the optimal acquisition. The SITHOS buoy lasted one year before the ice crushed it. The Iridium system worked flawlessly in temperatures below –40 deg C sending a total of 6 MB of data. It proved to be a very robust system ideal for this purpose.”
“This is an excellent example of Iridium’s ability to provide remote telemetry with very low latency in places beyond the reach of other satellite communication networks,” said Don Thoma, executive vice president of Iridium Satellite. “Remote satellite data for asset tracking and wireless machine-to-machine (M2M) communication is one of the fastest growing segments of Iridium’s business today.”
