Deep-towing begins

The last receiver went over the side of the ship around five this morning, completing the deployment of all 42 EM receivers in just 27 hours.  We then beelined for the start of the deep-tow profile and managed to get the EM transmitter SUESI, its 300 m long antenna and towed-EM receiver (at 500 m offset) deployed before the weather kicked up in the afternoon. When we first fired up SUESI to full power we heard some loud rattling coming from the top-side power supply in the back lab and then SUESI’s telemetry data feed went bad, so we decided to power down and start it up again, but again the rattling came back at high power. So we decided to revert to the spare power supply unit. However when we powered that one up, SUESI would no long talk to us and that started to get us all worried . We switched back to the original power supply and again SUESI wouldn’t talk to us. Oh no! Fear and anxiety and thoughts of a failed experiment started coming to mind. One option was to beach SUESI and switch to the spare SUESI, but that would have required a few hours of deck work in increasingly poor weather. So we opted to test some other things in the lab first, just in case…We swapped out the deck unit and that didn’t work. Then Steve Constable had the brilliant idea to swap out the deck box’s communication cable since that  was one of the components detached and then reattached we moving between the power supplies. Bingo! SUESI came back to life! Yay, no more failed experiment, at least for now!  But we still had the problem with the rattling power supply in unit #1 so we went with the backup power supply and fired SUESI up to 250 A. Using the ship’s winch, we lowered it down at a rate of about 30 m of wire per minute to a tow altitude of about 100 m above the increasingly deepening seabed as we tow down slope into 5500 m deep trench along this stretch of the Alaskan subduction zone.  If all goes well, we will complete our first CSEM profile in another two days. Photos and video from today below.

Samer Naif happy with the new antenna roller system.
Graduate student Christine Chesley at the helm of the deep-tow and winch control station.
SUESI being deployed