By Mike Carlowicz
Source: Woods Hole Current
They look like torpedoes--long and sleek and sturdy. But they do not bring harm; in fact, they sometimes help prevent it.
Remote Environmental Monitoring UnitS (REMUS) are low-cost, programmable, autonomous underwater vehicles (AUVs) designed and operated by Chris von Alt, Ben Allen, and colleagues in the WHOI Oceanographic Systems Laboratory. They were conceived for monitoring coastal environments, mapping shallow seafloors, and conducting multiple-vehicle surveys. But in the past year, REMUS vehicles have been adopted for more immediate public service.
In March and April of 2003, the US Navy enlisted several REMUS vehicles to detect mines in the Persian Gulf harbor of Umm Qasr during Operation Iraqi Freedom. While a few Navy-trained dolphins starred in front-page headlines, the REMUS vehicles quietly tracked back and forth through the harbor, making detailed sonar maps of the likely locations of mines. Navy officials told the media that they preferred using the AUVs because each REMUS could do the work of 12 to 16 human divers, and they were "undeterred by cold temperatures, murky water, sharks, or hunger."
In June 2003, a custom-designed REMUS swam several hundred feet below the Catskill Mountains and Hudson River to inspect a 45-mile section of the Delaware Aqueduct. It was the culmination of a three-year journey for the REMUS team. As the largest and most crucial link in New York City’s upstate water transportation system, the Delaware Aqueduct carries as much as 900 million gallons of water daily. For a decade, the NYC Department of Environmental Protection (DEP) has been monitoring leaks in the aqueduct’s Rondout-West Branch Tunnel, which have allowed 10 to 36 million gallons of water to escape each day. Yet inspectors could not simply shut off the water and walk inside for a visual inspection because the water pressure in the tunnel-about 240 pounds per square inch-might be the only thing that keeps the aqueduct from collapsing.
In 2000, the DEP issued a call for proposals to develop an untethered, unmanned vehicle that could inspect and photograph the 13.5-foot wide tunnel while the water kept flowing. The REMUS team saw it as an unprecedented challenge, and bid for the contract. They won.
Over the next three years, the team designed and extensively tested an oversized, customized version of REMUS, known as the Tunnel Inspection Vehicle. The TIV was equipped with five digital cameras angled for 360° imaging, as well as pressure sensors, hydrophones, and navigational gear.
On June 6, 2003, the TIV completed the 15-hour survey, emerging from the aqueduct with 160,000 digital photographs and 600 gigabytes of data that fills 150 DVDs. Engineers will now analyze the TIV data to determine the nature and location of the leaks, said DEP Commissioner Christopher Ward.
REMUS was invented and continues to be developed at WHOI, and is now manufactured by Hydroid Inc. of East Falmouth, MA. The Naval Sea Systems Command recently contracted with Hydroid for $30 million of REMUS technology. Several other municipalities with water issues are closely watching the results of the NY survey, with an eye toward perhaps acquiring a TIV of their own.