Sea Technology • APR 2019 • Page 26

LEMON Lander Pilot Frame to Accurately Position Long-Term Seaoor Observatory #Z%S&#0f;+JO&#0e;,ZV$IPJt%S&#0f;5BUTVIJSP'VLVCB T he Next-Generation Technology for Ocean Re-source Exploration is a ve-year project that was launched in 2014 as part of Japan’s Cross-ministeri-al Strategic Innovation Promotion Program (SIP). This project involved the development of a standalone seaoor observatory, LEMON lander (Long-term Eco-system MONitoring lander), for environmental impact assessment to protect and preserve ecosystems and biodiversity on a site of ocean resource exploration and exploitation. LEMON lander has environmental sensors to obtain biological, chemical, physical and video data on the seaoor and noncontact power and data transfer in-terfaces to add or interchange sensors and download stored data in situ for long-term observation in one lo-cation. A new installation method was inspired by multiple corer design to deploy LEMON lander as close to a target location and as safely as possible. This method allows pinpoint, safe installation even if an observatory is light in water and vulnerable to shock. Two LEMON landers were developed and have been deployed successfully on the seaoor in the Okinawa Trough in January 2018. Lander Design LEMON lander consists of ve hollow glass spheres (Okamoto Glass Co. Ltd., Japan), environmental sensors, and two noncontact power transmission and communi-cation interfaces. Four hollow glass spheres respectively house the camera unit, LED unit, control unit and battery unit. The remaining glass sphere is for functional exten-sion and buoyancy balance. To obtain environmental physical and chemical data in addition to visual data, a turbidity sensor, conductiv-ity and temperature (CT) sensor, dissolved oxygen (DO) sensor, current meter, and heat ow meter were installed. The dimensions of LEMON lander are 1.7 by 0.81 by 1.1 m (H×W×D); the weight in air and water are respec-tively 291 and 40 kgf; and the depth rating is 2,000 m. LEMON lander has sensors for environmental impact as-sessment and noncontact power supply and communica-tion interfaces for long-term observation. A grating for mounting the environmental sensors is de-signed to slide out from the body of the lander and frame like a drawer to minimize the inuence of the body and frame on sensor performance; the current cannot be measured properly if the frame and current meter are too close to each other. Noncontact Power, Data Transfer Interface Long-term monitoring in one location is required for environmental impact assessment because the natural environment changes slowly in the ocean. A noncontact power and data transfer interface was adopted to allow for replacement of malfunctioning sensors, adding addi-tional sensors, recovering stored data and checking oper-ation in situ through an ROV. One of the two noncontact interfaces mounted on LEMON lander is used to connect with the heat ow meter, and the other is for download-ing stored data and operational monitoring in situ. The noncontact interface was manufactured by B & PLUS K. 26 ST | April 2019 www.sea-technology.com