Posted by Bob.

Our last day on the sea ice started with the normal hustle and bustle of getting all the cases loaded and packing the Pisten Bully (PB) with the “System” components necessary to penetrate the depths of McMurdo sound with a miniature robot. With the checklists completed and the wind pants and bunny boots donned the crew of three in the PB were off. The lab seemed quiet until a tour came by and distracted me for a few moments with my 5 minutes description of our project. Cameo and I were going to be the Snowmobile team today. We move so much faster on the “sleds” as I like to call them, that we don’t have to leave until the PB has been gone for an hour. Even then we often catch them before they arrive at the day’s dive site. Cameo was dressed and ready to go. I was feeling empty, almost naked. I had forgotten something important and I couldn’t figure out a way to remember what it was. I delayed the application of my bunny boots and wind pants and stumbled around the lab hoping to find that thing I needed to make me whole again. A reorganization of my gear didn’t help. So now it was time to go.

As we walked past streams of melt water down to the snowmobiles staged at the sea ice transition we noted how much the ice was changing. In less than a week the sea ice would be closed. Travel on the ice would be restricted to only the absolute necessary. It’s not that the ice was getting too thin for safe travel, it’s more a question of the condition of the ice surface. A few large holes and several deep ruts had formed in the road over the last 24 hours and this deformation was expected to continue until travel would be destructive to both vehicle and occupants.

This is our last day on the ice and it was looking like a perfect day. The snowmobiles started fine but were in need of fuel. The complicated fueling system was now routine as we have done this check out many times over the last few months. Mac Ops received the mandatory call on the radio informing them of our project number, the names of the riders, the snowmobile numbers, our point of contact (someone who knew where we were going and a rough idea of what we had with us), and our estimated time of return. In this case, for some still not understood reason I said 5pm I almost always give our ETR (estimated time of return) in 24hour format and I always select 1900 as our return time, just before dinner. For some inexplicable reason I said 5pm. Holly who recognized me and greeted me by name read back the check out stating that she would hear from me by 1700. My brain clicked, ok 7pm.

The ride to the dive site was bright white. The weather this day was blue skies and light winds. A nice day to be on the sleds was enhanced by some classic rock in the mandatory earphones. I don’t listen to much music any more but if you’re going to put plugs in your ears it might as well be music. The helmets they issue us can’t cope with the loud sound coming from the two cycle engines. We made good time and in less then 30 min were at the same place the PB took almost an hour and a half to reach.

This dive site was on blue ice. This phenomenon is created when the winds blow all the snow off the ice then continues to encourage its evaporation by sublimation. The ice never actually melts. It is converted from a solid directly to a vapor by the urging of the wind. What this means to us is that we have to work on the equivalent of a skating rink. A smooth and glassy surface in all directions for hundreds of yards is now our playground. The nice thing about blue ice is that it drills easily. Aaron and I had drilled the holes for this dive yesterday and they had not even iced up much. The still liquid water in the holes means the chipper bar stays in the PB. Every thing about this day was smiles.

SCINI was prepped and the computers were set up and readied for a deployment. The pre-dive check list was completed and SCINI slipped her nose down the hole. Scott and Stacy were giggling in the control room at the wonderful alien world that lay 600ft below. All was working fine so Francois and I moved on to the day’s next task.

Our last dive of the season was to take SCINI down to 1000ft. This was the stated depth limit of the vehicle in the proposal and both Francois and I were eager to achieve it.

“Duh. That was it.” I feel so dumb. I was supposed to scrutinize the map on the wall for a likely dive site that was just over 1000ft deep. I had perused it many times. But I was going to spend some time and pick a really good spot. It kind of seamed like I had found what was missing from my morning. As we loaded the jiffy drill and five of the 8” drill bits on the snowmobiles I was sure we would find a spot that was 1000ft deep but the nagging emptiness was not fulfilled.

Our method of measuring the depth of the holes was quite ancient. Tied to the back of my snowmobile was a garden hose winder with a battery powered rewinder. What wasn’t on my snowmobile was any garden hose. I did have 1200 feet of ¼ inch nylon rope wound neatly to the spool. François had suggested a spot between Tent Island and Inaccessible Island. I started towards an imaginary place roughly between the islands and after a few minutes I saw a black not so imaginary dot in just about the place I had chosen. As the bumpy snow dunes continued to rattle by, the dot grew into what I was sure was a seal. Bingo! We may not need to drill a hole for this first test.

We stopped our Snowmobiles several hundred feet from the seal whom seamed to be dead. We walked towards the hole in a manner that could not be misunderstood as getting closer to the seal. It still had no response. The hole looked good so we attached the weights to the line and down the hole they went. At 600 feet was a knot attaching the second 600ft rope to the measuring line. Minutes went by and still the line slid down the hole with out any signs of slowing. The end of the line yanked on the spool we both tested the tension on the line and determined that the weights were still suspended safely above the bottom 1200 feet below where we stood. This was bad news. We want to dive SCINI on the bottom at 1000ft. we decided to use the snowmobile to pull the line out of the hole and this worked well if we went slow and stopped for the knot to be pulled up by hand. It was begging too look like the jiffy drill was in our near future. When we started the sleds the seal finally moved his head a bit and we drove off.

The next 3 holes drilled went fast and pulling the line up with the snowmobile was making things go even faster. But still no bottom contact. Finally we drove to a spot 600ft from the shore of Deception Island. This time the weight slowed its descent around 650 feet. Again we both hefted the line and could feel what we thought was bottom.

I used my GPS to determine the distance we were from the island. Francois did some quick math and the outcome pointed to a spot 40 meters further from the island.

A quick drill, and with a dunk the weight headed for the bottom. Bingo again, the weight stopped right at 985 feet: we had our dive spot.

We left the drill and the line spool there to ride back the current dive spot and help the others finish their dive. A few hours later and one short argument about the necessity of this not so scientific dive and we were back. It was almost 7pm so it was time to extend our check out for at least 3 more hours. The new dive spot had communications with Mac Ops and just about the time I made contact with them a curious helicopter made a nice big loop around our site. Mac ops indicated there had been search efforts in place for almost the last two hours. I was shocked. I was first in denial that I had checked out to 5pm instead of my normal 7pm. I was quite angry with myself. Mac ops called again with a message to meet with the NSF representative in his office first thing in the morning. This was big trouble. They had launched a helicopter. The dive site we had just left was in a spot where we couldn’t get good radio coverage. We didn’t hear them calling for us. This mistake was not to be taken lightly. It totally ruined my day. It was completely my fault and I couldn’t stop thinking about how much trouble I had caused.

The dive progressed normally. We attached a 200 ft tether to the 1000ft tether we had been using. This should give us some line to fly around with when we hit the bottom. We then dropped the tether with a clump weight down to 900 feet. The bottom loomed in to our display. It looked a bit sparse. Some sponge’s bryozoans and hydroids were scattered around. The depth sensor said 945ft. I drove deeper. Scini was handling well. It looked like we were on a steep wall. Now at 963ft. I turned towards the descending terrain. And drove her deeper to 990ft. More sponges. The tether seamed to be pulling on me. This was bad. If I was at the end of my tether we might not be able to go the 10 feet we needed. Our last depth record was 720ft. Scini was more then 100psi deeper then she had ever been. I turned again and carefully maneuvered her around some rocks. The camera dome at this depth has over 500PSI of pressure on it. A small scratch or nick could surely collapse the dome and flood the camera bottle. 987ft. I am at the end of my tether again. I come up and tried to drive straight out away from the clump weight to drag it over my way a bit. I descended again and the bottom looms at an indicated 975 feet. Driving forward I can get down to 999ft several times but I can’t get the display to show 1000ft. Frustrated I fly up again and descend again. Bingo for the third time today. The first number over 1000ft that I see on the depth indicator is 1007. We drive around there for a few minutes and our deepest indicated depth is 1015 feet. It’s been a long day, we have a lot of tether to wind up, SCINI has been in the water for almost 5 hours today. With the success of the deep dive helping to cheering me up a bit, we recover SCINI and pack all the gear for the last time this season.

Season statistics

Total in water time: 104 hours.

Total number of recorded dives: 44.

Maximum depth reached: 1015 feet.

Number of science objectives achieved: 3 out of 3.

Number of dropped chipper bars: 0.

Number of missed check-ins: 1 really big one.

The Snowmobile ride home was the highlight of the day. We didn’t want to get back to town too much ahead of the PB and we needed to do some searching for drivable cracks and potential sites for next year. First we drove the pressure ridges along Inaccessible Island. There were blue ponds of water in the low spots and rows of teeth looking stratified snow that had been thrust up by pressure pushing the sea ice against the shore. These weird shapes brought me back to the simple fact I was not in a place that existed on the planet earth. At least not as most people know it.