Tag Archives: distributed acoustic sensing (DAS)

The Ocean-Based Internet: Data Mining the Ocean

The U.S. Defense Department could one day place thousands of low-cost, floating sensors into the ocean to collect environmental data, such as water temperature, as well as activity data about commercial vessels, aircraft and even fish or maritime mammals moving through the area. But others also are dropping similar sensors in the world’s oceans, and defense researchers suggest many of those systems could be integrated into an even more comprehensive ocean-based Internet of Things.

The growing Internet of Things is mostly a land-based phenomenon, frequently in large cities with loads of sensors. But researchers at the Defense Advanced Research Projects Agency (DARPA) foresee a wide range of military and civil benefits from extending the Internet of Things out to sea.  The agency announced its Ocean of Things program in 2017. John Waterston, a program manager within DARPA’s Strategic Technology Office, says the sensors will float along the surface for at least one year, transmitting short messages via the Iridium satellite constellation back to a central location for analysis. “It’s a 280-byte in and 340-byte out message, so it’s a little bit more than a tweet. I like to say these things tweet about their environment,” he says.

The goal is to increase maritime awareness in a cost-effective way. Using existing systems to continuously monitor vast regions of the ocean would be cost prohibitive…. By coupling powerful analytical tools with commercial sensor technology, the agency intends to create floating sensor networks that significantly expand maritime awareness at a fraction of the cost of current approaches.

Waterston says one of the most interesting missions for the sensor might be to simply determine whether GPS signals are available in an area of interest for military operations. …The program also could help improve ocean modeling, which is important for forecasting weather, finding people who have fallen overboard or locating debris from a crashed aircraft. …The agency has yet to determine how many sensors it might eventually deploy, but they could number in the tens of thousands. To put that into perspective, DARPA officials compare the final density to placing a penny on the national mall, which Wikipedia says covers about 309 acres between the Ulysses S. Grant Memorial and the Lincoln Memorial….

In addition, Argo, an international program, uses several thousand battery-powered, robotic floating devices to measure temperature, salinity and current for climate and oceanographic research. The floats mostly drift 10 days at a time below the ocean surface. After rising and transmitting their data to satellites, they return to depth to drift for another 10 days. The floats go as deep as 2,000 meters, according to the Argo website. 

Argo Floating Device

It is possible an ocean-based Internet could provide data on demand to a variety of customers inside and outside the Defense Department. If, for example, a government agency needs the water temperature in a given area reported every six hours, or a combatant command needs to know what’s happening in the Mediterranean, or NATO officials want information between Gibraltar and Sicily, or commercial fishermen need data on where the shrimp or tuna are, they could simply request it. “It’s about serving the end users. If you can use that data, we can generate it for you,” he offers. “It’s a little bit like floats-as-a-service or data-as-a-service.”

Argo’s Ocean Sensors

Another option is that other organizations could purchase and deploy the DARPA-developed sensors. “I hope people want to come up with their own sensors or want to buy these. I imagine a marketplace where you get many commercial people buying these. Everyone could buy 500 and then take advantage of the service provided by the thousands that are out there. I could imagine this as that foundational community,” Waterston suggests.

DARPA currently is working with three teams led by the Palo Alto Research Center, better known as PARC***, Areté Associates and Numurus LLC to develop the floats. Leidos, Draper Laboratory, SoarTech and Geometric Data Analytics are providing software for data visualization, performance prediction, float command and control and detection. 

Excerpts from George Seffers, DARPA’s Ocean of Things Ripples Across Research Areas, AFCEA.org, Nov. 1, 2019

***See also DARPA’s Vanishing Programmable Resources (VAPR) program. According to one scientist that works in the PARC’s disappearing electronics platform (called DUST) “Imagine being able to cover a large area, like the ocean floor, with billions of tiny sensors to ‘hear’ what is happening within the earth’s crust, and have them quickly disintegrate into, essentially, sand, leaving no trace and not harming the planet or sea life,  

Fiber Optic Cables and Surveillance

[T]he technology known as distributed acoustic sensing (DAS)… allows underground fibre-optic cables, like those used by telecoms companies, to be turned into a giant string of microphones. They can then be used to monitor all sorts of sensitive locations, from oil and gas pipelines to railway tracks, military bases and international borders. In its latest guise, DAS is even being used to help make hydraulic fracturing, or “fracking” as it is known, more efficient at releasing natural gas and oil trapped in rocks.

There are some limitations to the technology. Its powers of hearing are not sufficiently acute to pick up a conversation, for example. And since the cables inside buildings are typically a tangle of short lengths interrupted by junction-boxes, it is unlikely to work there. However, a long cable buried outdoors can provide the equivalent of a microphone every ten metres.  Algorithms are used to establish acoustic “fingerprints” for the sounds that are detected; and depending where and when they occur, each is assigned a level of risk, says Magnus McEwen-King, OptaSense’s managing director. Footsteps around a guarded facility at midday may not be unusual, but at 2am they would be.

OptaSense is also using the system to monitor sounds coming from below ground, in particular those produced by the water, sand and chemicals pumped under high pressure to fracture rock during fracking. There is concern about exactly what is going on underground, and in particular if the process might contaminate aquifers. Various seismic sensors can be used to monitor the fracking process, sometimes from test bores drilled nearby. But it is a costly and tricky process.

Shell and other oil companies are using a DAS system, which OptaSense calls vertical seismic profiling, to monitor their fracking. It uses a fibre-optic cable inserted into a well bore to build up an acoustic picture of the fracking fluid going into the rock at multiple levels. This means that potential problems, such as blockages, or leaks from one layer of rock to another, can be spotted before they become serious. And by having a clearer idea of how much fluid is going where, the fracking process can be constantly adjusted so that it runs in the most efficient way.

Listening for intruders and monitoring the efficiency of fracking are just two of the potentially lucrative applications of DAS technology. No doubt there will be others in the pipeline.

Acoustic sensing: The ear underground, Economist,  January 4, 2014, at 62