Data Emerges From Below
27 August, 2010
By Michael Dessner
A Big 2 Days
The last two days have been as eventful as any I’ve ever spent at sea. Last night at 1 AM, Mary Ann was recovered with good data from her long range survey of the entire Titanic wreck site. After getting her situated in her hut we all snuck into the lab to wait while the data downloaded, hoping to get a glimpse at the imagery before we had to go back to the deck to prepare for Ginger’s arrival on the surface which was anticipated an hour or so later. Almost immediately we received telemetry from Ginger that indicated her batteries were running low informing us that she would not likely have enough power to finish her mission. Not the end of the world, she was programmed to cover the same area Mary Ann surveyed but from a different direction, her last two lines would likely be well outside the debris field in any case so we were pretty well covered.
Only minutes later we found that she had an even less power remaining than originally thought and had aborted her mission due to a preprogrammed safety protocol that commanded her to do so. This ensured that she would have enough power when she reached the surface to communicate with us, run her strobes and make a phone call over the Iridium network to tell us where she was should we fail to contact her (that’s right, they phone home). Upon hearing that she was en route back to the surface we had to leave the lab and the developing data to get ready to pick her up.
It was an hour or so later that we gathered back in the lab to look at data. As both vehicles were on the surface and had good data we really had to wake the mission leadership up and wait for them to join us before we ran through the sonar record. We were just a bit jumpy to get a peek at the initial results obtained after months of planning, weeks of equipping and days of sailing and operations. We all seriously wanted to see the first site survey to fully map the entire region around and including the wreck of the Titanic.
We waited, not so patiently, as the group gathered. Talked of previous careers. Discussed the J Geils music playing. Turned off the J Geils music playing. Turned on a little Mozart (I know, surprising what a classy bunch we are). Soon enough all were present and the moment we’d all been waiting for had arrived. Andy rolled the data. It was nice and clean, no noise or other issues. A discussion about the color scheme being used on the screens ensued regarding whether the shadows were black or white. A wager was placed. A Diet Coke was lost. Don’t worry Dave Gallo of WHOI, I won’t let anybody know that you owe Andy Sherrell of Harbor Branch Oceanographic Institute a Diet Coke.
The only guy in the room at the time who had been here before was Bill Lange, the underwater imaging genius from Woods Hole who designed the HD and 3D cameras to be used on the ROVs during the photographic inspection dives. The sonar map maps we are creating will serve to guide his missions. As Bill was the legacy he played the part of guide as we all watched some fairly dramatic sonar imagery of the ocean floor scroll down the screens.
Again, results from sonar are not pictures: it is a visual representation based on the reflectivity of a target and the strength of the return of the sonic energy bounced from it back to the sonar transducer. Those images require interpretation. What looks like a ridgeline may well be nothing more than a portion of the bottom that has all the sand scoured off it by the current exposing the rock beneath; it may not necessarily rise off the bottom at all. That is why shadows contain so much useful information; you can measure the length of shadows to help you understand how high something rises. The contours of the shadow will also define the shape of the object much like the shadow from a flashlight would.
While we watched the initial lanes of the data scroll Billy would comment on this or that as we tried to orient ourselves to the wreck. As we had not seen any of the previously mapped and photographed structures in the sonar record yet it was still guesswork as to where we were. Then the moment we had been waiting for: what appeared to be the bow of the ship appeared on the screens and that put everything else into perspective, gave us our orientation. That’s when I finally had to crash after 22 hours on the job.
The Morning After
This morning I found we got exactly what we had hoped for from the missions and those images have gone out around the world. I am sure many people are wondering what the big deal is, it’s a tad anticlimactic compared to photography and the long range sonar stuff does no justice to the sense of scale of this site. It needs to be pointed out, the site has never been fully mapped and from what I understand there are still many discoveries to be made. Not all of the ship has been found and the extent of the debris field has never been fully understood. Our work yesterday helped us plan the work the AUVs and Remora will accomplish tomorrow, and that should be an order of magnitude more dramatic.
Currently the girls are down on the site running a higher frequency, and thus higher resolution, sonar. The range scales are going to be a lot shorter, they won’t cover as much ground in as much time but we now know exactly where we want to further develop our understanding and that’s where they’re headed. Aside from sonars Ginger is carrying a camera and Mary Ann the multi-beam. This downward looking sonar hits the area with many more pings per second and although the swath is much narrower we will be able to “see” the site in 3 dimensions once it’s processed. The multi beam data combined with the higher resolution sonar and the mosaic we will generate when all the photos come aboard will give the ROV team a new resource to explore the site, a complete map of the area with exceptionally accurate navigational info. That highly enhanced navigational data will give the ROV pilots a new capability and understanding of the debris field that did not exist before we arrived. It will be a development that will be as stirring and important as all of the work that has gone on previously.
I’d like to say a word about my team out here. The Waitt Institute owns and tasks the AUVs but we collaborate with Woods Hole Oceanographic Institution, specifically the OSL lab, to operate and maintain them. The men in this group are, aside from being the bunch that developed this technology, exceptionally skilled engineers who put in extremely long and difficult hours. We also work with another electrical engineer from Harbor Branch Oceanographic Institute, a good friend of mine named Andy Sherrell. He does our sonar analysis and this is our 7th voyage together. On this trip I have seen most of these guys work 20 hour days since our arrival in Newfoundland and they will continue to do so until we pull into port. It’s grueling and they deserve recognition for their effort. Without them the AUVs could not perform as magnificently as they do. In the coming days I will likely profile some of them, I hope you enjoy meeting them as much as I enjoy working with them.
Our Neighbors at Sea
One last personal observation. The pilot whales were back today in force, had to be at least 20 or 30 of them on the surface very near the starboard rail of the ship late this afternoon. It looks like they are feeding on something near the surface, today it looked like a few of them tried to stay almost on top of the water. Their languid glide through the water, their proximity to the others, almost ‘leaning’ on each other as they feed, is compelling. I know whales are social animals with huge ranges but it feels like they want to hang around with us (although I’m certain there is an upwelling or something of the like nearby that has them in the area feeding). There is an elegance and economy of movement to them that I find oddly reassuring and serene. I hope you all have the opportunity to see them in their native habitat someday. They bring to my mind buffalo, a species that once permeated the biosphere they inhabited, placid in the huge numbers that once ranged across our continent. Now you almost have to go to a zoo to see one. I hope for all of our sakes that this is not the resultant case with whales. I have no understanding or even comprehension of those who would hunt or enclose these graceful, highly social and peaceful mammals. A pox on those who prey upon the cephalopods.