Ms. Callaghan’s Classroom
Jil Callaghan is a 6th grade science teacher at Houck Middle School in Salem, Oregon. She is posting blogs for her students while aboard the Research Vessel Sikuliaq as part of a teacher at sea program through Oregon State University.
Earlier this week we deployed a glider that belongs to the University of Alaska at Fairbanks (UAF). What’s a glider? It is an underwater robot that “flies” around the sea going from the surface to the bottom of the seafloor collecting different types of science data.
The glider does not have a propeller or motor to push it through the water, instead it uses buoyancy and a 10 kg weight. Brita adds or subtracts weights (based on the density of the water) to make it neutrally buoyant so that it floats at the surface. When it needs to dive, the glider moves the weight forward, which changes its center of gravity, and makes the nose of the glider point downward. The weight is moved backward or forward by a screw; it slides along as the screw rotates.
In the nose cone, it has a diaphragm – a plate that moves to allow water in or push it out. When it allows more water in, the glider becomes negatively buoyant and starts to sink until it reaches the depth that Brita told it to go to. When the glider needs to go back to the surface, it does the reverse; the diaphragm pushes water out, the weight moves back, making the nose of the glider point upwards.
The glider can run on its batteries for up to 3 months, and all you have to do is pay for the upload of data via satellite, which is about $200/day, vs. $50,000 a day for a research ship the size of the Sikuliaq. “It surfaces approximately every 2 hours and sends us snippets of data over satellite so we can see how the gilder’s doing. It sends small subsets of data – the full set of data we get when we physically collect the glider,” says Brita.
This glider is measuring salinity (how salty it is), temperature, it has a couple of pressure sensors so it can tell how deep it is, a fluorometer, which is an optical instrument which measures chlorophyll (what phytoplankton and plants use to take light and CO2 to make their own food), CDOM (Colored Dissolved Organic Matter), and back scatter (how much stuff is in the water that blocks the light). It also measures pC02, partial pressure of carbon dioxide (how much carbon is available to the organisms in the ocean).
Unfortunately, after only one day in the water, the glider had part of its electronics flood with water. The glider is part of UAFs research and development, and with research and development there are always failures that drive the next improvements and advances. Such is science!
See Ms. Callaghan’s other posts here.