Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Alkor	AL552b	07.04.2021 - 09.04.2021	REEBUS MOSES	Eckernfoerder Bucht Baltic Sea

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Sommer Stefan	Helmholtz Centre for Ocean Research Kiel (GEOMAR)	Kiel	Kiel

Ziel der Reise / Objectives of Cruise:

Major aim of the short Alkor cruise AL552b (07.-09. April 2021) was to conduct a first underwater test of the newly developed Deep-Sea Rover (DSR) Panta Rhei. The DSR Panta Rhei represents a six-wheeled benthic vehicle, which is specifically designed to carry out repeated benthic oxygen flux measurements inside flux chambers for prolonged time periods of up to one year. Beside the DSR Panta Rhei, further tests with regard to positioning and a homing algorithm were conducted of the crawler/lander system VIATOR and MANSIO. These tests were performed within the framework of the Helmholtz and BMBF funded projects ARCHES, MOSES and REEBUS. Tests of the Rover and the MANSIO/VIATOR system took place in the working area A1 at the entrance of the Eckernforde Bay at the north-eastern slope of Mittelgrund in water depths of 15 to 18 m. This area provides ideal test conditions, the gently sloping terrain offers different seafloor types, encompassing sandy sediments in shallow depths, which with depth become progressively muddy. Further test series took place in the Strander Bight (working area A2), which was more sheltered and thus offered better conditions for the diving operations. Working depths comprised 10 to 16 m, whereas shallower grounds were rather sandy with occasional occurrence of stones. The seafloor at 16 m was characterized by dark soft and sulfidic mud. In the morning of the 7th April after a short transit, we started station work at about 10:20 (CEST) in the working area A1 by deploying the lander/crawler system MANSIO/VIATOR. Afterwards the DSR Panta Rhei was deployed for its first field test. Two tests of the DSR Panta Rhei at Mittelgrund were successfully completed. The test protocol of the Rover comprised its mobility, repeated insertion of the two benthic chambers, the automatic volume determination of the bottom water enclosed by the benthic chambers and oxygen measurements. During the evening hours, further tests were performed with the VIATOR and MANSIO with major focus on testing a homing algorithm for VIATOR to locate and move autonomously to the stationary lander platform MANSIO. At the 8th of April, diving operations were successfully performed in the Strander Bight to provide better shelter for the diving team. The first dive was conducted to observe the driving-behavior of the DSR Panta Rhei on sandy ground in 10 m water depth. A second dive was carried out to record the behavior of the Rover on a soft ground in a depth of 13 m. After finishing the diving activities, we continued further tests of the MANSIO/VIATOR system with specific focus on the homing function. In the morning of the 9th April, station work started with the recovery of the Rover. A brief evaluation of the data and photo material revealed that the Rover unfortunately got stuck in the very soft, black and sulfidic sediment. Subsequently, the Rover was prepared for its last deployment during this cruise. This deployment of the DSR Panta Rhei was filmed by the Submaris diving team, whereas the ZDF Terra X team filmed the preparation, deployment and retrieval of the Rover onboard of RV Alkor. Overall, we successfully conducted the first field tests of the DSR Panta Rhei and made major advances regarding the positioning and homing function of the MANSIO/VIATOR system. Scientifically relevant data were not obtained during this test cruise.

Messungen / Measurements