ENDURANCE

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

We awoke to the sound of tents fluttering madly in 25 knot + winds—katabatics coming down the valley. The temperature rose to 3C (37F). Bill prepared the mission plan this morning, an ambitious 22 sonde casts to mop up the entire southwest quadrant of the lake. While this was underway Vickie pulled the sonde flags from the November 9 and 11 missions and she and Rachel re-labeled them for today’s run.

Mission plan for November 16 called for another ambitious sonde cast run to clean up the southwest quadrant of the lake.

Meanwhile, the strong winds played havoc with our melt hole wind screens, lifting up and tossing heavy ballast ice into the hole that had been piled on the sheets. Vickie and Kristof went to work and re-anchored the ends of the flaps (seen as the yellow colored panels on the four sides of the moon pool access port in previous photos) using ice screws and some clever rigging tricks Vickie had picked up on other expeditions.

Project PI, Peter Doran, arrived on a helo flight at 11am, in time to participate in the team meeting. By 12:33pm the vehicle was underway. It returned at 6:35pm in a textbook mission, acquiring all 22 casts: D5, D8, C4, C5, C6, C7, C8, C9, B3, B4, B5, B6, B7, B8, B9, A2, A3, A4, A5, A6, A7, and F6 without incident. The latter station is included in all missions as a time varying measure of lake activity over the season. Total distance traveled underwater today was 2.7 kilometers with an in-water run time of 6 hours. We still had more than 40% power reserves at the conclusion of the mission.

Kristof preps the pH sensor on the sonde before launch.

Vickie locks in on the bot position for the 22nd sonde cast of the day.

After being with us during the tedious start-up phase for six weeks, SAS chief engineer Bart Hogan began the long return to the US and his family today, hopefully arriving in time for Thanksgiving. Given the substantial changes and improvements made to the hardware and software on ENDURANCE over the past year, Bart’s presence on the field team was of enormous benefit. Thanks Bart!

SAS engineer Bart Hogan leaves the valley after six weeks on the ice.

Sonde cast progress at the conclusion of the November 16 mission.

Reporting by Bill Stone

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

Most people did not get to bed until 3 or 4 am so it was a welcome sight to find John Priscu up at noon cheerily making crepes for everyone who walked in the door of the Jamesway at East Lake Bonney. Today was an off day. Many people caught up on their blogs… a luxury since our science days here are excessively long and most people are dog-tired by the time dinner is over. Somehow sitting down to write at 2am after 18 hours on your feet is difficult. A tent and sleeping bag seem more appealing. It was also a chance to look through data from the past several days at a less break-neck pace.

John Priscu hands out crepes in the Jamesway.

Shilpa, John, and Emma eventually went on a hike up to the ventifact field some 600 meters vertically above camp. Kristof went for a run along shore to the east. Chris built two snowmen (given the rare snow storm of yesterday). Vickie read Memoirs of a Geisha. In training, Bill did 155 pushups. Most watched an “Austin Powers” film following dinner.

Shilpa, Emma, Chris, Bart, Kristof, Vickie, and Chris’s creations “Frostie Boy” (left) and “Dr. Stone.” By the time Chris got to work most of yesterday’s snow storm had ablated.

Reporting by Bill Stone

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

We awoke to news that McMurdo was in Condition 1 (no travel). Here in the valleys it snowed during the evening at the higher peak levels but down low it was still dry.

During the routine (but extensive) pre-mission checklist we found that one of the six thrusters was showing a low level of pressure balance volume so it was taken out for maintenance and a spare swapped in.

Rachel completes the swap out of the #2 thruster for maintenance.

Prior to yesterday we had planned to incrementally (and conservatively) work our way out towards the “narrows” separating east and west Lake Bonney some 1.5 kilometers east of the lab. Using the revised mission planner and the improved battery behavior we realized we could acquire all of the remaining east end sonde casts in one mission. A year ago we had felt it would be required to have a secondary melt hole near the east end for “inflight refueling” and had re-designed the charging system on the vehicle for that purpose. Now with the improved vehicle travel efficiency and double power onboard it appeared we could run significant east end forays.

Our plan for today was to conduct sonde casts at E17, E18, E19, D21, E20, F19, F18, F17, E16, E15, E14, F14, and F6. Total mission length would be 3.2 km.

The mission began at 3:52 pm and the vehicle returned to the melt hole at 10:30pm with all sonde points acquired. Importantly, we had conducted a detailed multi-beam side-looking survey at two locations at western head of the Narrows. Multibeam was able to image all the way to shore on both sides. Depth at lake center in this area was 11m under keel, leaving enough to consider a more advanced mission in which the bot actually drove through the narrows and into East Lobe. At D21 (our furthest point today) we were just out of sonar range to image the location measured by Scott.

Marking the furthest exploratory mission for ENDURANCE, Vickie tracks the bot at 1.5 kilometers from the melt hole. Behind her is the “narrows” between west and east Lake Bonney, looking into East Lobe. Scott’s team took measurements here December 17, 1903.

Shortly after turn around (although still with more than half the sonde casts remaining to be performed) we had our only technical glitch for the day—at F19 communications dropped out for an unnerving 30 seconds. Then it suddenly came back. Shilpa analyzed the data and began searching a section of the onboard code she had been suspicious of for some time, ever since the earlier data link drop outs. With nearly 100,000 lines of software running the bot this would have been an insurmountable task during a mission, but Shilpa had spent a lot of time tracking this over the last 10 days and now found it—a “memory leak” in a routine designed to track the status of certain vehicle systems. Unchecked on a long mission, the errant process filled up memory and died. When restarted, it freed up memory and the system came back. The fix, until a more optimized re-write of that section could be performed, was to pre-empt and periodically re-boot that process—one of scores running the vehicle. Given the location of the bot at the time (1.5 kilometers from the hole) this was an impressive bit of thinking under pressure on the part of Shilpa.

At 8pm, still more than a kilometer from the lab, the grapel (1mm diameter micro hail) storm began with persistent 25 knot up-valley winds. The lab was already invisible from station F14 and we joked about having to navigate the tracking team back to the lab by following the bot home under the ice. By the time the tracking team returned there had been an accumulation of 1 inch of snow by completion of mission.

The grapel storm turned into a blizzard, obscuring the lab from 500 meters out in a white out.

Vickie gives Rachel a break from fiber tending following the 6 hour mission.

By 11pm the bot was on its sled at the lab. Power reserve was 21% when the it reached the melt hole, following a total of 7 hours 3 minutes in the water. At end of mission we found the bot very positively buoyant—adding the 8 kg dive bag we use to lower it each day would not get it underwater. Heavy micro-bubble formation had occurred all over the bot. There were also micro-bubbles all over the sonde (down-looking) camera window.

Shilpa, Bart, and Chris watch the new situational awareness visualizer at mission control as the bot “discovers” the melt hole on return from its long trip.

Status of all sonde casts (green = completed) as of November 14, 2009.

We drove home to East Lobe camp at 1am.

Reporting by Bill Stone

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

The lead team of Vickie, Kristof, and Bill was up at 6:40am and off to the bot garage by 8am. They reloaded both battery stacks into their housings and into the bot, then reconnected power lines and re-installed ballast lead. By 10am the system was powered up and showing 100% power charge.

By noon the bot was over the melt hole for the sonde instrument calibration. Outside, winds began to pick up steadily from South Pole (katabatics) to 30 knots gusting to 35 knots. Wind gusts hitting the north end of the lab were violently shaking it—every time it moved it blew out the heater. The air temperature at the start of the mission was a warm 32F but dropping.

We shortly received a radio briefing that helicopters were grounded at McMurdo for at least two days, preventing arrival of chief project scientist Peter Doran. At 12:20pm we performed a sonde test drop to 18m depth to verify changes made by Chris and John to the sonde instrument parameters—all looked good on the live sonde monitor at mission control so we proceeded. By 12:30pm the bot was down at 5 meters depth and performing a test of ice picking behavior. This time, due to variations in temperature, the vehicle was proving to be too heavy so we recalled it to the melt hole and removed 500 grams of ballast.

The ambitious 3.2 kilometer sonde mission planned for November 13, including 19 sonde casts.

The wind was blowing down valley strongly for the entire mission without let up. Going eastward the tracking team was being forcefully pushed ahead; coming back was a fight. Taking tracking beacon readings were difficult — the wind was blowing the coils and the wind drone made it difficult to hear the tone.

The mission was successfully concluded at 7:15pm with an automated ascent up through the melt hole and a 25% remaining power reserve. We had completed 20 sonde drops today: G12, G13, F14, F15, F16, G16, G15, G14, H13, H12, H11, F13, F12, F11, F9, E7, D7, D6, E6, F6.

The total mission length was 3400 meters, including additional post-return navigation testing that was performed in the vicinity of the melt hole involving the USBL secondary localizer. Following the additional navigation tests the power was down to 12% and still usable, validating Bart’s hunch of several days ago regarding the battery balancing.

The team returned to camp at 9:20pm (an early night for us) and discovered to everyone’s dismay that the winds (which were still driving hard) had uprooted Shilpa’s and Chris’s tents. After dinner the entire team broke out replacement tents and helped set new sites up, these tied down to bigger rocks.

Status of all sonde casts (green = completed) as of November 13, 2009.

Reporting by Bill Stone

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

The mission today was clear: find the cause of the communications system failure of yesterday. We had already tested all the elements of the external system yesterday (fiber, data converters) and the internal data hub itself proved to be functioning correctly when run off an external power supply dialed to the appropriate drive voltage. Similarly, the onboard power supplies were also working correctly. It took eight hours to methodically go down the list of likely contenders. In the end, the theory that wire terminations in a screw-type termination block had oxidized and thereby reduced the voltage getting to the communications hub had proved correct. In effect there had been a power “brown out” that was enough to drop the hub for the remainder of the mission after the initial failure at G11. There were parallel communications (via internet) going on with several members of the SAS engineering team in the U.S. and elsewhere to confer on this subject. Ultimately, we pulled the wires leading to the data hub, trimmed them, reterminated and soldered them and then re-installed into the terminal block. The system powered up normally. The general conjecture was that the bot had sat in the MEC engineering center in McMurdo station for 10 months between the last power up and that this had given time for a loose connection to oxidize enough to manifest itself as a reduced voltage coming out of the power supplies. We pre-empted at this point and re-terminated all the other wires going into this same power block.

Vickie connects a local computer interface to the Profiler housing. Using this and an external laptop computer we were able to respool the instrument sonde.

Chris checks voltages on a power supply terminal strip in the main computer processor housing.

The suspect power terminal block.

With refurbished connections, Chris successfully logs into the bot through the wireless interface.

Rachel reassembles the main computer. This is actually a stack of several processors. Overall there are 45 computer processors in ENDURANCE.

Meanwhile, Bart used the down time opportunity to play out a hunch regarding the 20% “stranded” power in the batteries. the new design, completed just in time for this season, used two stacks of batteries in series along with custom circuitry to balance the voltages. But that circuitry had to get its power somewhere and it was connected to the first half of the stack, slowly causing the voltage there to drop below the other stack. Safeguard circuitry looked for the lowest cell in the system and if it fell below a certain value (for fire safety) it disconnected the battery. What Bart discovered was a significantly larger power draw by the monitoring circuitry than was needed to run it. So a modification was made to the boards to reduce this demand by a factor of ten. Some test calculations indicated that at the new level of power draw from the monitoring circuits that the overall voltage balancing system would succeed (it was not designed for differential power draw). With the two halves of each of the power stacks (the vehicle uses two sets of two stacks) now balanced (manually) and the control circuitry installed, we anticipated a significant change in available power. Tomorrow’s mission will tell.

Reporting by Bill Stone