ARTEMIS

Checking On Our Water Current Profiler

The sonar face is free of ice accumulation. (photo: Peter Kimball / Justin Lawrence)

The safety rope attached to the sonar is not free of ice accumulation. (photo: Peter Kimball / Justin Lawrence)

Justin and I went out to the fish hut today to check on our water current profiling sonar. We refueled the generator, verified that the computer is still logging data, and lowered a camera & light into the hole to check for ice accumulation on the transducer face. With everything in good order, we headed back to town and refueled our Pisten Bully.

Reporting by Peter Kimball

Installing a Water Current Profiler

John, Vickie, Chris, and I installed an Acoustic Doppler Current Profiler (ADCP) in the drill hole at our candidate field site on Saturday. This instrument emits sound pulses into the water below at a known frequency and then measures the Doppler shift in returned echoes to determine the velocity (magnitude and direction) of the water currents below. We’re leaving the instrument running out at our candidate field site and traveling out to refuel the generator that’s powering it whenever weather allows. We’re hoping to gain an understanding of how tidal activity drives water currents there, and thus be able to plan our robots’ dives so that the robots aren’t swimming upstream any more than necessary.

Bill and Josh worked up a frame to secure the instrument in a known orientation in the fish hut. We installed the frame on Saturday after chipping out accumulated ice from the sides of the drill hole. We ran into a problem when the cordless drill batteries wouldn’t function in the cold and we Macgyvered a solution with a power supply, two multimeter leads, and a wine cork. Worked great!

Reporting by Peter Kimball

Condition Fun

McMurdo Station uses three weather “conditions” to define weather-related travel restrictions. They are:

Weather Condition 3:
Unrestricted travel and activity are allowed.

• Winds less than 48 knots, and
• Visibility greater than or equal to ¼ mile, and
• Wind chill temperature warmer than -75°F.

Severe Weather Condition 2:
Restricted pedestrian traffic only between buildings is allowed. Vehicular travel is only allowed in radio equipped, enclosed vehicles, and check out with the Firehouse is required.

• Winds 48 to 55 knots sustained for one minute, or
• Visibility less than ¼ mile, but greater than or equal to 100 feet sustained for one minute, or
• Wind chill -75°F to -100°F sustained for one minute.

Severe Weather Condition 1:
Severe weather is in progress. All personnel must remain in buildings or the nearest shelter.

• Winds greater than 55 knots sustained for one minute, or
• Visibility less than 100 feet sustained for one minute, or
• Wind chill greater than -100°F sustained for one minute.

We’ve had Condition 1 a few times here so far. When Condition 1 struck McMurdo tonight, we were stranded in the galley for 45 minutes (not too bad). But, because people can end up stranded in all kinds of strange places when Condition 1 hits, there is a famous McMurdo band called “Condition Fun”. I think that’s an amazing name, and I’ve borrowed it for the title of this post. Check out their original song, C-17.

Here’s a photo I took of the steps into the galley after a Condition 1 storm.

The steps into building 155 are covered in ice and snow following a Condition 1 weather event. (photo: Peter Kimball)

Reporting by Peter Kimball

Checking Out Our Candidate Field Site

We had a great day today deploying Sunfish at our candidate field site. It was not a bright sunny day, but there was enough light coming through the ice for us to learn quite a bit from the imagery. The platelet ice accumulation is certainly significant, but so far, we haven’t seen anything too scary from a robot operations perspective. Here are some stills from a GoPro I attached to Sunfish for today’s dive.

We ran the vehicle battery all the way down exploring the area around our fish hut. We were just about to start some other experiments at the surface when the weather changed dramatically. We had been commenting all day about how nice and not-too-cold it was outside. Then, over the course of about 15 minutes, the wind came up to 60 mph, and visibility dropped to less than two car lengths. We packed up our gear and drove back to station in close formation, navigating our route over the sea ice by GPS.

Reporting by Peter Kimball

First Sunfish Dive at our Candidate Field Site

We returned to our site on Wednesday night after our access hole was drilled that morning. One group worked for two hours to clear platelet ice from the access hole while another group loaded Sunfish and its support gear into a vehicle and brought it out to the site. The fish hut was cozy with a heater running and seven of us inside.

After doing some checkouts on the vehicle systems, we deployed it down through the drill hole. It was the middle of the night (we still have darkness for the time being), so we didn’t see the glowing blue ice ceiling. The camera view was completely black except for backscatter from the headlight, and an occasional view of the vehicle tether or the ice ceiling when we got very close. There’s still quite a bit to learn about the conditions at the field site, but we did use the opportunity to test a number of vehicle sensor systems, particularly those relating to the swift moving water currents present at the site. Once again, we left the test happy, but with a list of tests and improvements to work on for the next dive.

I set up a GoPro camera on Sunfish for this dive and came home with hundreds of images of headlight backscatter in dark dark water.

Fog forms in the Sunfish drill hole as cold air from below mixes with warm air in the hut. (photo: Sunfish/Peter Kimball)

Sunfish points down the drill hole. The headlight illuminates platelet ice on the walls of the hole. (photo: Sunfish/Peter Kimball)

The Sunfish headlight illuminates platelet ice accumulation near the drill hole. (photo: Sunfish/Peter Kimball)

Reporting by Peter Kimball