ENDURANCE

West Lake Bonney, Taylor Valley, Antarctica
Reporting from East Lake Bonney Basecamp

Sunday is “brunch” day at McMurdo Station, so the team met for breakfast at 11am before going their separate ways to begin sorting out their various chores and responsibilities. Four of our crew (Peter, Shilpa, Kristof, and Chris) were scheduled to leave on the C17 flight on the 8th, in just two days, so they were more pressed for time than the rest to resolve any open issues in town (a lot of equipment had to be returned to various labs; offices had to be cleaned up and gear stowed; data had to be backed up; and any excess personal cargo had to be boxed and shipped).

Peter Doran and Bill Stone presented the Sunday Night Science Lecture at McMurdo to a crowd of about 150 in the main dining hall in Building 155. These lectures are a frequent place to catch up on what other field researchers have underway, what conditions exist out on the ice, and what logistics problems are currently at hand. Even as our team was leaving Taylor Valley, other crews were coming in for their 2-month projects.

Sunday Night Science Lecture series poster for December 6, 2009.

Peter Doran describes some unusual Sonde down-look camera images from West Lake Bonney at the Sunday night lecture.

Reporting by Bill Stone

West Lake Bonney, Taylor Valley, Antarctica
Reporting from East Lake Bonney Basecamp

At 7am Peter Doran came around to every tent in East Lake Bonney camp and woke the crew up one by one. Despite the cloud cap the word from McMurdo was that the helos were flying, and there was much to do today. Everyone crash packed their tent, sleeping bags, pads, personal clothes, and ECW by 8am and had lugged them down to a growing pile below the helipad just east of the Jamesway. At 8:10am Vickie, Rachel, Bill, Maciek, and Jim headed for the bot garage to join the carpentry crew for the dismantling of the now-empty lab structure. Kristof, Chris, Peter, and Shilpa were scheduled for the first helo flight back to McMurdo and stayed at ELB to pack.

By noon the tarps, insulation blankets and framing (tubes) were all down and boxed. We used a rolling scaffold with two persons on top and two ladders on the mid-sides.
We had to move the bot (on its sled) to the side of the platform to allow passage of the scaffold; otherwise it all went well. The carp team remained on site handling the preparation of sling loads for several more helo lifts expected in the afternoon. For our team, however, it was time to quickly retreat to ELB camp and make one last pass through the Jamesway to ensure everything was packed. It was time to go meet our science cargo back in McMurdo.

Maciek removes one of 17 mylar thermal blankets from the bot garage siding.

The interior, final shell of the bot garage presses against the tube frame in the up-valley wind.

With the superstructure of the bot garage stripped away and all of the science gear packed in cargo crates and sling loads, ENDURANCE stands alone in its own ECW gear, awaiting pickup.

The art of Antarctic Dry Valley conservation: Vickie, Rachel, Maciek, and Jim cart off seven 5-gallon bio-hazard drums of human waste from the yellow pyramidal Scott tent outhouse by the bot garage. The orange 55 gallon drums contain six weeks of urine. Nothing is left behind.

A B-212 helo dropped in on ELB camp around 2:20pm. We had already hauled all our bags up and had them sitting beneath the helo pad so it was a matter of putting on ECW jackets and white boots and running up. They handed out helmets and we crammed six of us in the back along with all our orange bags (sleeping kits had been left under the helo pad for later pickup).

Packing out: personal helo bags (orange) stack up outside the ELB Jamesway on December 5th. Each person gets two such bags. Science cargo goes separate.

The final hike to the helo pad for the ride back to McMurdo. Six people in full ECW gear with their personal belongings fit into the B212.

The housing office handed out keys when we arrived. Some people fared worse than others in the lottery: Kristof, Chris, Maciek, and Jim got bunks in the infamous Hotel California. Emma and Shilpa, on the other hand, got their own rooms in Building 203. So ended the 2009 field season. For some of, however, it would be another week in McMurdo, packing equipment for retro to CONUS.

Reporting by Bill Stone

West Lake Bonney, Taylor Valley, Antarctica
Reporting from East Lake Bonney Basecamp

The crew was up and at the lab at 8am and facing the substantial task of breaking everything down that had been set up for the past six weeks and getting it into the appropriate shipping containers, “Triwalls,” and readied to be lashed into cargo nets for pick up by the helo fleet that would now be visiting us like mosquitos on a hot summer evening.

Vickie, Emma, and Rachel disassemble the bot instruments for safe packing.

Looking like a quartet of killer whales breaching the surface for breath, the bot syntactic sits on a sea of frozen ice on West Lake Bonney, awaiting closure for helo pickup.

Chris, Kristof, and Shilpa re-load 2 kilometers of fiber optic data comm line for retro to CONUS.

By 4pm the first half of the team was heading back to ELB camp to begin packing up personal things in preparation for tomorrow’s expected retro to McMurdo. Along the way to ELB a team of four from the carpentry shop led by Chad McNaughton passed on their way to begin preparation of helo sling loads for the cargo boxes that our team had assembled. Several loads left for McMurdo today including all of our diving gear and a compressor in one sling under a B212. It was like Anti-Cargo-Cult mysticism… You laid out the loads on the ice and they disappeared before sunset. It was always impressive to watch when the McMurdo helo fleet kicked in. And to them we owe a debt of gratitude for their awesome service both in 2008 and 2009.

Bell 212 Helo “Oh-Eight-Hotel” carries a half ton of diving gear out in one lift.

There was one final piece of unfinished business for some of us. After having stared at the looming Matterhorn peak (see November 5, 6, and 22nd logs), 1860 vertical meters above our camp, everyday for 6 weeks and with precious few hours left this year before departure, Kristof, Chris, and Bill set off to climb it at 5pm. The weather was stark clear and the wind had died. Despite the good weather the three each carried ECW gear, food, water, and radios. Six hours later they reached a point about 200 vertical meters below the summit and found the route too steep with snow and ice to safely continue without technical ice gear. The view, from a vertical mile above camp, well above the southern Kukri Hills that flanked Taylor Valley, was one that would last in memory forever. The absolute pristine beauty, the stark geometry of rock and ice, of banded exposed geology, and the vista that went for more than a hundred miles, was stunning. We could see over the Kukri Hills to the south and beyond the Asgard Range to the north. McMurdo Sound was visible to the east. The descent was swift and sure and the team was back by 2am, in time to celebrate the return of Maciek Obryk and Jim Olech to ELB. They would help us take down the bot garage in the morning.

Chris (left) and Kristof make their way up the final basalt, dark-rock summit pyramid on the Matterhorn. Far below is the Matterhorn Glacier which, itself, is close to 800 meters above East Lake Bonney, far, far below.

A forever view looking north into the Asgard Range from near the summit of the Matterhorn.

A bizarre wind-eroded basalt pillar ventifact some 200 meters below the summit of the Matterhorn gives the appearance of a host of spirit faces scrutinizing the arrival of the climbing team. The angular distortion is deceiving—the pillar is actually vertical and the boulder slope is close to 45-degrees to the vertical.

Reporting by Bill Stone

West Lake Bonney, Taylor Valley, Antarctica
Reporting from East Lake Bonney Basecamp

Mission Objective: Limno “no fly” zone bathymetry cleanup—final mission 2009; auxiliary navigation experiments; autonomous automated sonde mission down deep axis of lake if energy remains.

After a considerable amount of discussion and planning we sought to wrap up all remaining data collection and vehicle control experiments for 2009 in one final mission. The primary objective was to fill in the bathymetry map southeast of the LTER limnological cables. For this we would have to employ the diversion pole for the 4th time. The mission profile was complex and contorted and we hoped to fill in some of the northwest gaps left over from the November 30th mission. Last, we planned to test the finalized sensor-fusion Sonde cast system on a short mission down the deep axis of the lake through waypoints AC01 and AC02.

The complex December 3, 2009 bathymetry mission had as its initial objective the completion of lake floor mapping southeast of the LTER limno cables (shown as a cluster of four maroon spots south of AC02). It then proceeded north to fill in gaps in the November 30th mapping zone, and finally ended with automated sonde tests east of the melt hole.

The final mission was uploaded at 11:15am and the vehicle as in the water and neutrally ballasted 21 minutes later. The vehicle subsequently failed the ice-picking test at 11:48am and we brought it back and removed 1 kg of ballast, this time taking the precautionary measure of locking the nav solution prior to ascent through the melt hole. This procedure subsequently proved effective. The mission proceeded smoothly and it was supervised, although not interfered with, at mission control throughout the entire run.

Chris (right) continues work on the enhanced sensor-fusion automated-sonde code while Shilpa and Kristof monitor today’s mission.

The issue of the changing ballast requirements has remained one of the curious mysteries of working in Lake Bonney. From day to day—and even during the conduct of a mission—and with no physical changes to the vehicle from one mission to the next, the buoyancy has been seen to vary as much as 10 kg. Originally this was thought to be a result of the “microbubble” phenomenon discovered here in 2008. There, we believed that super-saturated gas dissolved in the water was allowed to leave solution due to the pressure drop associated locally with the vehicle’s thruster props. It would frequently adhere to the vehicle skin as white fuzz. This, however, had the effect of increasing the buoyancy of the vehicle, which altogether was not a problem for Sonde missions. The issue of increasing negative buoyancy following an otherwise positively buoyant state in the melt hole could potentially be explained by cold shrinkage of electronics housing and flotation or possibly by trapped bubbles compressing with greater depth. But great efforts were undertaken at the start of each mission to “burp” the vehicle of any trapped gas. So this issue remains for consideration for future sub-glacial autonomous systems operations.

At 4pm the bot detected a very large boulder on the north shore of the lake, on the order of 10 meters in diameter. At 4:35pm Mission Control interceded in the mission in a planned test of one of the auxiliary navigation systems (the iUSBL). In this test Mission Control induced a failure state in which the dead-reckoning navigation system went off-line. The vehicle control system picked up on this and successfully navigated back to the melt hole on the iUSBL system for the remaining 150 meters of this first part of the mission. By 4:44 pm we initiated the second half of the mission: an autonomous sonde run east of the lab. With no intervention the bot conducted fully automated sonde casts at F6, AC03, and AC04 (parallel to, but offset to the north of AC01 and AC02). Also, given that a large rock had been detected in this zone on the outbound journey to the limno zone we were able to use this information for further fine tuning of the roll calibration on the imaging sensors. Total mission length for today, not including the final sonde run, was 3,318 meters with 4.3 hours of under-ice time. With this mission complete the 3D geometry of sub-surface West Lake Bonney was complete (see figure). As of 6pm today, with the bot safely back, all mission objectives set forth for the ENDURANCE project had been met and in most cases exceeded by substantial margins.

Results of today’s supervised autonomous bathymetry mission. Complete coverage (and more) was achieved in all target zones (shown by the blue polygons).

By 6:21pm the moon pool cover had been closed for the final time and a group photo of Team ENDURANCE 2009 was taken. The rails were disassembled and taken outside. The Sonde was removed and packed. By 8:04pm the four syntactic flotation quads were in their yellow shipping transport cases and moved 50 meters west of the bot garage, within helo pickup range. All of the battery stacks (5 of them) were packed and stacked. At 8:30pm the 10 kW diesel base generator was powered down for the final time and we drove back to the Jamesway at ELB. Just two days of packing and break down remain in Taylor valley.

The composite result of all bathymetric data acquired in 2008 and 2009 by ENDURANCE. The entirety of West Lake Bonney is mapped along with the Bonney Riegel Narrows (where Scott’s party passed in 1903) as well as several hundred meters out into East Lake Bonney. There are other data, from obstacle avoidance sonar as well as glacial mapping from 2008 that are not shown here that fill in remaining sections up to the face of Taylor glacier. In all the map represents several hundred million measurements and by orders of magnitude is the most detailed map of any sub-glacial lake currently known.

Left to Right: Kristof Richmond, Chris Flesher, Emma Steger, Vickie Siegel, Rachel Price, Shilpa Gulati, Peter Doran, and Bill Stone.

Reporting by Bill Stone

West Lake Bonney, Taylor Valley, Antarctica
Reporting from East Lake Bonney Basecamp

Mission Objective: Narrows sonde mission temporal duplicate run (to capture the effects on water chemistry through the connecting sill between East and West Lake Bonney due to melt water runoff since the last run through the narrows on November 18th).

The crew was up at 6:30am working on data reduction and blogs and at the bot lab by 9:30am. At 10am Kristof delivered to Bill the previous mission’s ice picking pose coordinates. These were re-plotted in the mission planner to obtain the true location for NR7. This particular location had been moved 50 meters further into East Lake Bonney at John Priscu’s request on the original November 18th narrows mission. Since we now had GPS locations for the true points, these were used to establish the target waypoints for today. The batteries completed charging and were re-installed into the vehicle at 11:23am. By 12:13pm the bot was back together and on top-off charging. The IMU was aligning and the mission plan was uploaded. At 12:40pm the bot was underway to the narrows following an initial failed attempt at ice-picking adjacent the melt hole. Ice picking was one of our final checks before releasing the vehicle on a mission. In this case the vehicle was too heavy and would not float up under the ice—a requirement on all our Sonde missions for conservation of energy while conducting the sonde cast. We commanded the vehicle back up the hole, removed a kilogram of lead and sent it back down. This time it passed the ice pick test and we sent it on its way.

Chris tests the stack balances in the batteries before they are re-loaded into the vehicle for the December 2, 2009 mission to the Bonney Riegel narrows.

The mission plan was similar to the November 18th run with the significant changes in vehicle path at both the beginning and end to accommodate filling in missing gaps in the bathymetry data. Specifically the vehicle was targeted north to BA60 to BA63 on the outbound mission and to BA64 to BA67 on the return. The sonde casts through the narrows were identical to the prior mission.

At 2pm the bot reached the pivot target R2 just north of the Narrows. The navigation was off by 2.5 meters and Bill and Vickie on the ice tracking team reported this via radio to mission control. This was not enough error to cause any problems with the fiber diversion system (in place at waypoint “Pivot 2”) but by the time it reached the first scheduled sonde cast waypoint, NR2, the error had grown to 4.5 meters. The ice tracking team re-vectored the bot to the waypoint and the GPS coordinates were uploaded to the navigation solution, essentially re-initializing it to those known coordinates. The mission proceeded on schedule and on target from that point forward. By 6:15pm the bot was a half kilometer from the melt hole, having acquired all of the sonde casts at NR1 through NR8 and carrying a battery reserve of 32%. By 6:23pm it was 150m from base with 28% reserve. At 6:40pm the bot found the melt hole and automatically began its ascent. The auto-docking sequence was halted and the vehicle was put into station keeping mode while a new set of instructions relating to automated sonde cast testing was uploaded. The vehicle was then sent back down and retargeted to F6 where a fully-automated sonde cast was successfully accomplished using the new sensor fusion code. A full test of this new system was scheduled to take place at the conclusion of tomorrow’s final bathymetry mission. By 7:18pm the bot was back at the lab.

Vickie tracks the bot in real-time with RTK-GPS during the December 2, 2009 mission through the Bonney Riegel narrows.

The full picture of the narrows with Bill Stone standing directly above where Scott’s party stood in 1903 (with 16.2 meters in water level rise). See the November 18th, 2009 log entry for a cross section plot at this location.

Vickie Siegel acquires the last of the GPS fixes for the sonde cast waypoints. With an 80 minute transit time for the bot to return from the pivot point at R2 to the melt hole, the ice tracking team retrieved the white pivot tube (seen attached to the ATV), collected the remaining flag markers, and their coordinates.

In a post-mission debriefing we discussed the navigation error at NR2. Kristof hypothesized that it was due to the fact that the bot failed the first test for ice picking at the start of the mission. It was brought back and some lead was pulled off. Normally, once the navigation solution was acquired and the bot launched the vehicle moved in a smooth succession with all sensors acquiring data. Aside from eating up power (which proved to not be a problem) the apparent problem had been that the navigation solution had been updated without the benefit of several key sensors—which were shielded by the melt hole. Without those sensors in the loop, the position estimate was coming only from doubly-integrated accelerometer data, which is known to drift over time even with the very high grade accelerometers installed in ENDURANCE. This was enough to inject both a positional error of several meters and a slight angular misalignment at the re-start of the mission and this extended to NR2 where we reset the solution to the absolute coordinates there (acquired by GPS). With the main nav sensors operating the solution maintained lock for the remainder of the mission. The total under-ice run length, not counting the excursion to F6, came to 3,982 m today with an under-ice mission duration of 5.6 hours. The sonde cast data were excellent and formed a complete data set with which to compare to the set acquired three weeks earlier.

Lake bottom bathymetry was paved in and on target, mopping up the last of the gaps in the eastern half of West Lake Bonney. Only the area southeast of the limnological experiment zone remained to be scanned.

Reporting by Bill Stone