We had an awesome day today. The first mission of the day was to try and get pictures of the grounding line of Taylor glacier. We had attempted this yesterday, but were not able to get the bot close enough to lip of the glacier to take pictures. We still could not get close enough to get pictures of the grounding line, but we were able to take pictures of the lip and confirm that it was ice, and of the lake bottom and confirm that it was sediment. In addition, we saw some interesting low temperatures (less that -4 degree Celsius) during our sweep, indicating fresh water inflow from the glacier. The second mission was an automated bathymetry mission where the robot performed a side sweep of the shore. This mission was entirely automated and worked perfectly. It was very nice to sit back and watch the data flow and the visualizations. I will let the pictures do the rest of the talking.
If you are interested in the details of the visual homing algorithm below, please visit my publications page.
We start every day with a short meeting. Everyone was looking forward to new discoveries.
The bot drove to the glacier melt-hole and surfaced up using visual homing. We added weights to the bot here to enable it to descend and be neutrally buoyant at a depth of about 22 m.
Images taken by the upward looking camera on the bot during visual homing to rise up the glacier melt-hole. During visual homing, the bot moves in a spiral pattern to search for a light source, finds potential targets, identifies a blinking light as the target, centers on it and then rises up the melt-hole. The water was turbid and the collimated light was barely visible unless the bot was right underneath it. The first image shows how the algorithm identified the light but failed to lock on to it since the bot was not directly underneath the light. On the arm of the spiral, the bot was underneath the light and locked on to it. The light appears bigger as the bot ascends the melt-hole.
After ballasting, the bot drove underneath the halocline to the glacier lip. A visualization showing the bot approaching the lip. The beams radiating from the bot are sonars whose returns help us construct this visualization.
The bot underneath the lip of the glacier. This mission kept us on edge all the time because we had to be very careful to not let the bot get wedged in the narrow cavity, yet get enough close enough to capture images.
Image of the glacier lip captured by the forward-looking camera.
Image of the lake bottom beneath the lip showed sediment. This confirmed that the glacier does not go down all the way to the bottom but floats.