The MARS Ocean Observatory Testbed
History of the MARS observatory

Despite these three setbacks, a great deal of work proceeded on many fronts during the two years it took to obtain the environmental permits.

MBARI needed to identify the best route to run the cable and to assess where, and how deep, the cable would be buried. Fugro Seafloor Surveys Inc. was contracted to undertake a marine survey and to prepare a cable burial assessment. Fugro staff performed the survey aboard the R/V Western Flyer in November 2003.

WHOI developed the Data and Communications System (DCS) based on Cisco 3750 routers, EDFA (Erbium Doped Fiber Amplifiers), and network electronics DWDM (Dense Wavelength Division Multiplexing) optical communications. They also developed the out-of-band communication system and the precision timing subsystem (1 microsecs).

In April 2005, technicians at L-3 MariPro (a private marine technology firm) finished construction of the MARS science node. In this photo you can see that the node has two parts: a removable inner module (yellow) that contains all of the wiring and electronics and an outer metal frame (red) that protects the node from damage due to fishing nets. Image: (c) 2005 Nautronics MariPro

The low voltage (LV) power system was designed and developed at APL. This system took the 375V from the medium voltage (MV) power system and converted it to 48V, 12V, and 5V for powering the internal and external loads. The low-voltage system also incorporated the ground-fault detection system and the power monitoring and control system, which enabled monitoring of the voltage, currents, ground faults, environmental sensors, and science-port switch status. It also enabled current limits to be individually set for each science connector.

The low-voltage power system and DCS were delivered to MBARI in early 2005 after a brief integration test of the two subsystems at APL.

The medium-voltage power system was being developed by JPL. This system consists of two redundant converter systems, each comprised of 48 individual converter stages that convert the 10kV to 375V, together with their coordinating circuit and output plane. This subsystem would be housed in its own pressure housing filled with fluorinert to cool the electronics. The 375V would be delivered to the low-voltage system via an interconnect cable between the medium-voltage and low-voltage/DCS housings. This system would eventually experience major technical problems leading to many delays and financial problems.

MariPro designed the MARS node, which is comprised of the trawl-resistant frame (TRF) and the node itself. An early meeting between the MARS team, ROV Ventana pilots, and MariPro led to a design where all of the active electronics would be housed in a node that would be slightly positively buoyant in seawater so that it could be readily recovered using MBARI’s own ROVs. This was essential for long-term maintenance of the system. If recovery of the node required a cable vessel, the system would be unaffordable. The node would sit inside the TRF, a large, orange steel frame, which would protect the node from potential hits from trawler boards used by fishermen. The TRF would interface to the cable termination assembly (CTA) that would be delivered by Alcatel. MariPro designed the two titanium pressure housings, backbone structures, science harnesses and connectors, and the thermal management system. Image at right shows the systems designed by MariPro being tested in Goleta, California, in April 2005, just prior to being delivered to MBARI.

Alcatel designed, built, and tested the cable termination assembly (CTA). The CTA incorporated proven qualified technology based on branching units used by the telecommunications industry. A new element was the incorporation of hoses and connectors designed and manufactured by Ocean Design Inc. (ODI) to enable the node to be disconnected from the CTA and brought ashore for maintenance operations. The CTA was the first subsystem to arrive at MBARI in January 2005.

In early 2005, MBARI received the last of the permits to install the cable. With the shore landing drilling scheduled for early 2006, all but one of the subsystems delivered to MBARI, and the cable installation contract in place, MBARI was planning the system-level integration at MBARI for the second half of 2005, followed by the cable installation in mid-2006. The only subsystem remaining to be delivered was the medium-voltage converters from JPL which had been built and were about to be powered at full voltage for the first time in July 2005.

Unfortunately, on start up, the medium-voltage converters experienced a major failure after a few milliseconds of operation. Inspection did not determine the cause of the failure. Over the next three months the initial failure was followed by two more start-up failures. A review panel of experts was formed and worked with JPL to provide an assessment of the situation.

At the end of September, JPL submitted the recovery plan to MBARI. The cause of the failure was still not clearly established, their estimated cost for the recovery was unaffordable, and there was still no guarantee of success. If it failed again, MBARI would be left without a working system. At that time, Alcatel was in the process of developing the medium-voltage converters for the NEPTUNE Canada system and offered MBARI the prototype medium-voltage converter for a fixed price. Alcatel was soon under contract to deliver the MARS converters. Although its design was based on the JPL converters, Alcatel also soon ran into technical difficulties, and the original six-month delivery extended into over 18 months, even with a large, experienced design team on the program. The early prediction that the high-voltage power converters would be a high risk element for regional scaled observatories was proving to be correct.

Environmental Crossings Inc. installs the cable shore landing in Moss Landing.

The late delivery of the medium-voltage converters allowed many of the APL low-voltage power system boards to be redesigned and respun to correct some ground-fault design problems that arose during integration and testing at MBARI. They also replaced fused field-effect transistors and resolved some board manufacturing problems. The reworked low-voltage system was delivered to MBARI early in 2007.

In early 2006, Environmental Crossings, Inc., was contracted by MBARI to drill and install a five-inch steel pipe from the end of Moss Landing island, under the canyon, to a location 3,200 feet offshore for the cable shore landing. This work was successfully completed in March 2006, ready for the cable installation.

With Alcatel under contract to deliver the medium-voltage converters in early 2006, everything appeared to be lined up ready for a cable installation in late 2006. However, as the Alcatel delivery date slipped, the cable installation was delayed to early 2007. As the delivery date slipped further and further, end-to-end testing of the entire system was no longer possible, and MBARI had to proceed with the cable installation before the 16 permits expired.

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Last updated: Oct. 07, 2009