Now, that our bags are packed and many of the team members are on their way out of Finland (which makes us sad), some questions can be addressed and the real blogging can begin.
This blog will address the first question that Team CONCUR has received. Which is “how and why UBC-Gavia, the AUV, got lost?”.
First of all, UBC-Gavia is a sophisticated piece of scientific instrumentation; however, no matter how much planning goes into her missions, once she is under the ice, many things outside of our control can happen.
After we recovered UBC-Gavia, the team ran a scientific postmortem using the information that we gathered from data logs, GoPro video that was attached to the AUV, the position of the vehicle when recovered and the observations we made when we were trying to recover her.
We won’t ever be 100% sure what happened, but here is our best guess.
On her final mission, UBC-Gavia was launched under the ice and for some reason, she didn’t dive to the set depth that she was supposed to. She chose to run along the underside of the ice (this can be heard near the end of the following video, it’s the scraping sound).
She continued along her mission line; however, she decided to abort. This could have been due to her not being at the set dive depth, or maybe she wanted to play hide-and-seek. To us, her abort meant that she needed to be pulled back into the hole by her tether. When we tried to do this, she came towards the hole a little. But, then all of a sudden she stopped and we could no longer pull on the rope. From this point on, we had no way of getting UBC-Gavia out.
From the GoPro video, and the observation that we couldn’t hear her using the hydrophone, it appears that when we were pulling her towards us, she popped up into an open hole in the ice and sat in the ice. This prevented the hydrophone pingers to work in the water.
Normally, we would have been able to free UBC-Gavia from this hole, but there were also knots in her tether line that got stuck in the ice. This is what we think finally did us in and had UBC-Gavia dead in the water.
It wasn’t until the ice had finally started to break up and melt that we could see the line to save UBC-Gavia, but boy are we ever happy that the ice started to melt.
More questions and lessons learned to come in future posts.
Seuraavaan kertaan! (Until next time!)