We finished deploying all 42 (err, now 39) receivers at 10:55 AM and then headed 10 nautical miles up the profile so that when we turned back around to tow SUESI down the line, we would be getting nice deep-sensing long offset CSEM data on the first receiver. SUESI was in the water and transmitting by just past 2 PM, and the rest of the day has quite peaceful and relaxing, including sunny skies and a pod of whales spouting about a kilometer from the ship most of the evening. Jupiter is visible just about the horizon again too. Photos and a video from today below.
Timeline of our 39 receiver deployments in just 18 hours (first deployment is on the lower right).Christine working the antenna winchThis little rocket (called a Vulcan) is towed about 500 meters behind SUESI’s antenna and measures the electric field at short offsets to constrain shallow conductivity in the seabed. Its primary data is the in line electric dipole receiver formed by the electrode on its nose and tail, but it also measures the cross-line electric fields using electrodes on the four wing tips.Jake, Chris and Janine taking the Vulcan to the stern for deployment.The Vulcan towed receiver with an acoustic transponder in tow behind it. Since there is no GPS signal below the sea surface to record the deep-tow positions, we range on the acoustic transponder from SUESI, and it relays pings up to other transponders we tow on the sea surface, and then SUESI records the three way travel times, as well as direct travel times from SUESI to the surface transponders. Since we use pressure records to measure the depths of both SUESI and the Vulcan, and we record the GPS positions of the surface transponders, we can then back triangulate the lateral positions of both SUESI and the Vulcan.Eric, Janine and Li helping to deploy SUESI’s neutrally buoyant antenna cable.Janine attaching a glass floatation sphere to SUESI’s neutrally buoyant antenna cable since its actually not neutrally buoyant when we attach 50 foot long 5/8” thick walled copper pipes to it to use as electrodes for the output current.SUESI getting ready for deep-tow deployment to 5.2 km depth in the Alaskan trench.SUESI with antenna cables attached and ready for deployment.
SUESI being deployed for our second profile. We start deep-towing in the shallower water on the continental shelf and so unfortunately the visibility is a bit low compared to the deep ocean receiver deployment video I posted yesterday.
SUESI deploy Line 3
Clear deck means all the instruments are in the water collecting data. So much easier to deep tow in these light seas than in the rough weather we had last week.
