Two more instruments on deck

Following last night’s endeavour, we were back in the main lab by 6 Am to oversee the recovery of the next station. The entire recovery process lasts a few hours. First the ship comes to a halt about 2 km away from the deployed site. The seismology and magnetotelluric groups will attempt to communicate with their respective instruments. If communication is difficult, the ship would slowly move closer to the instruments. Once communication is established, the OBMT instrument is released from the ocean floor first. Then, a survey establishing the exact location of the OBS is performed by sailing along a circle of 2 km radius around the original OBS deployment site. Following the survey, which lasts about an hour, the OBS is released. The instrument starts the burn cycle which last about 10 minutes during which a trigger is sent to release the weights that hold the instrument down on the ocean floor. The techs continuously communicate with the instruments to ensure that the they are rising steadily. Both the OBMT and OBS can take between 1 to 3 hours to rise to the surface, depending on the depth they are at. As the instruments rise to the surface, the ship comes to a halt at a safe distance and everyone on deck keenly stare into the horizon to spot the instrument when it come up to the surface. Both the instruments were recovered by 12:30 in the afternoon. Another happy moment for all of us!

The next station is a fair distance away. The estimated time of arrival is 9 Am on 8th March.

An acoustics unit that is patched into the ships transducer to communicate with the ocean bottom instruments.
Research techs hard at work
If the flashing beacon fails, we have an “ecto-graph” (think of ghost busters) to find the instruments!


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