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Also, Iridium was built for voice communications only. It will only get data support in a couple of years when they will literally send up a completely new full set of satellites.

Data has been sent via Iridium as a matter of course for years. I know from experience with floats and autonomous underwater vehicles that modems are commercially available and used every day. We got usable throughput on the order of a couple of hundred bits per second with a very unfavorable antenna location inches above the sea surface.

Here is such a modem.

Also, Iridium was built for voice communications only. It will only get data support in a couple of years when they will literally send up a completely new full set of satellites.

Data has been sent via Iridium as a matter of course for years. I know from experience with floats and autonomous underwater vehicles that modems are commercially available and used every day. We got usable throughput on the order of a couple of hundred bits per second with a very unfavorable antenna location inches above the sea surface.

Here is such a modem.

This is similar to the autonomous glider the people at the Large Lakes Observatory use to get data from something that's not moored in one place like research bouys are. The unit here in Duluth cruises around Lake Superior for a few weeks at a time, but they're standard equipment for oceanographers in bigger, saltier puddles too.

It uses the same means of propulsion: turning up-and-down motion into forward motion with wings. Its power source, however, is some onboard batteries rather than a solar cell limiting its endurance (but freeing it from dragging around the solar rig, so it can go deeper and faster). All the battery does is change the volume of a swim bladder, causing the glider to float or sink. Amazing efficient!

Here is another maker of similar products.

http://www.webbresearch.com/

The company I work for, Rockland Scientific, designs sensors that can be attached to these subs. Some of them are rated for 6000m - kind of makes 600' look like a joke...

But another method of collecting data is to simply have floating sensors. Similar data is collected but there is no propulsion except for up and down. Every so often they surface and transmit their collected data. Then they go back down and continue drifting with the current. They are typically used in a disposable manner and only last 5 years. The advantage of these devices is that they are far less costly. It is also convenient to have them follow the ocean current. Around 1000 of these sensors are placed into the ocean each year. A french company makes them, wish I could remember the name.

That's funny. An intelligently designed autonomous underwater vehicle seems to have no trouble getting GPS fixes when surfaced.

Further details on the glider from the designer's web site: http://www.webbresearch.com/thermal_glider.htm

It's all explained here:
http://www.webbresearch.com/slocum.htm
It's a "heat engine which draws energy from the ocean thermocline". These engines were discussed a lot in the previous /. story.

J

It looks like the other one has a mustache too. Oops. Wrong guy. I mistook him for someone who is president.