McMurdo Day 35: Huddle Test 1

We set up a "huddle test" on Monday -- a short test to make sure our seismometers are working correctly.

It's PASSCAL best practice to test seismometers after they've been shipped down from New Mexico to Antarctica.  Originally, Avi and I were going to huddle test all the POLENET sensors at WAIS to make sure they were working after a bumpy flight in a Twin Otter plane. Then we'd make sure the sensors were good to go before bringing them out to the POLENET sites.

However, as we all well know, things did not go to plan and we are not at WAIS. But we've decided to huddle test the sensors anyway so we know if they are working (and they can be left in McMurdo for next season or shipped back to PASSCAL) or not (so we can ship them back to the manufacturer to repair).

Seismometers are sensitive instruments, and McMurdo is a pretty noisy place (with tractors and the lot zooming around all the time). In order to see if the seismometers are actually functioning as intended, it's best to test them in a quiet place. The Castle Rock test site is perfect for this!

I spent Monday morning gathering equipment to take with us to test the sensors. We needed the typical equipment for setting up a station: dataloggers, GPS antennae, charge controllers, and (of course) the sensors. We had to get a bit creative with the cabling for all of this, as you will see shortly.

I heard that PASSCAL had an "antenna moose" that we have used for huddle tests in the past. I walked over to one of our storage areas to find it, with the plan of carrying it back to Crary. I'm not sure what I was expecting, but it certainly was not an 8-ft tall aluminum pole with 8 antenna dangling from it and a giant coil of cables at the bottom. Needless to say, I did not carry this monstrosity by myself all the way up the hill to Crary. I left it and improvised with other antenna-mounting techniques. As you will also see shortly.

The Antenna Moose. An apt name for the 8ft tall antlered creation before me.

Luckily, there were already plenty of batteries at the site to power the huddle test. However, the plywood box we dug/PistenBullied out a few weeks ago was in-use for Test Plot 1. So we needed to finish digging out the second plywood box. Our friend from the CTBTO group helped us dig most of it out last week; Avi and I just finished digging around the corners, and then did our PistenBully-cargo-strap magic trick to break the box out of the ice underneath.

Plywood box #2, just before we cargo strapped it to the PistenBully and wrenched it free.

And I can't forget to mention the terrible part which is that this plywood box was filled with 20 AGM batteries (at 65 lbs each!) that we had to move out of the box before PistenBullying it loose, and then back into the box after we'd moved it up to the surface.

Did I mention. TWENTY 65-LB BATTERIES. Lifted ONE-BY-ONE out of a 6-ft deep hole. In other news, I have real, visible biceps now.

As we were moving the batteries + box, I noticed some cool hexagonal ice crystals on the bottom of the plywood box and on some of the battery terminals. I gladly took a battery-moving break to take some close up pictures.

Bottom of the plywood box.

Plywood box close-up. Look at those beautiful hexagons!

Hexagons on the negative battery terminal. Don't let the beauty fool you, though. This battery is still extremely heavy and the worst.

There was a lot of fresh snow at the test site from all the snow we got last week. It filled in some of the solar panel holes we dug, which was rather unfortunate for Avi, because he fell in one up to his armpits.

Avi attempting to pull himself out of the snow with a shovel.

After Avi had rescued himself and we had moved the plywood box and batteries, it was time to install some sensors. As I've mentioned previously, seismometers must be level and oriented facing true North when they are installed. I went through the three seismometers and oriented and leveled each. And then accidentally bumped one with my shovel. And so re-leveled and re-oriented it.

Me orienting a sensor to true north.

Three level and correctly oriented 120PHQ sensors! I placed a piece of plywood on top and covered it with snow.

So back to the cabling solution. We used a model of datalogger called a Q330. Q330s are quite old and do not supply enough power for the sensor type we installed (120PHQs). In a normal setting, like sites for POLENET, where we are installing one Q330 inside one giant orange enclosure, this problem is taken care of. The sensor cable attaches to the enclosure bulkhead, and on the inside, the cable is broken out so that power comes directly from the charge controller and data goes directly to the Q330.

However: Avi and I did not want to lug 2 more giant orange enclosures out to the test site just for a short 2-day huddle test. So we improvised. We found two random bulkheads floating around the Crary lab and just used them as a way to break out the sensor cables. The bulkheads also have many other cables (which in a normal setting are used to bring the GPS and solar power into the enclosure). These cables were not connected to anything, and just make the whole setup look extremely messy and ugly. Oops. This is what happens when we get to be creative.

Everything is working perfectly, if also looking like a rat's nest.

Meanwhile, sans moose, the antenna were mounted with the very clever solution of just zip-tying them onto the solar panel mounts. What a great day to be a PASSCAL engineer.

Our completed huddle test setup, with Avi representing our gold-star work.

I took very detailed notes the whole time, just in case we need to look back at them later. Or provide any rationale for our creative design choices. I turned these notes into a drawing back in the lab.

I made a very nice powerpoint drawing of the site layout for future reference.

Most of the time we were setting up this huddle test, the test site was covered in fog. It made for a spooky atmosphere.

Fog over the test site.

You didn't think I'd end this post without a picture of me and my bff, PistenBully 314, did you??

Three-fourteen you're so fine, you're so fine you blow my mind, three-fourteen!