It's all around you, thinking on its own and acting on its ownthe Sensor Web, that is. The Sensor Web Project is a cutting-edge application of networked sensor technology currently on the fast track at NASA's Jet Propulsion Laboratory (JPL). Other kinds of sensor networkssuch as mesh networkshave grabbed headlines recently, but NASA and JPL officials claim that Sensor Webs go far beyond anything we've seen before.
Essentially, a Sensor Web consists of a group of podssmall metal boxes set up to collect various kinds of information, communicate with nearby pods, and in some cases, communicate wirelessly with outside devices. What's inside a pod varies but typically includes a microcontroller, microprocessing and computer-like components, cellular communications technology, acoustic sensing components, and more. In many of the current applications for Sensor Webs, a group of pods is designed to collect environmental information. (You can find a complete online description of how a sensor Web works at http://sensorwebs.jpl.nasa.gov.)
"I'm at NASA, and there is much interest in deploying Sensor Webs to explore planets," says Kevin A. Delin, the leader of the JPL Sensor Webs Project. "One of our first applications for a Sensor Web has been to put one in remote regions of Antarctica. You can think of each of the sensors and pods we put there as pixels in an overall picture. And just as a rover on another planet might react to conditions in an environment, the Sensor Web can too. The group of pods collects information about the environment and we can get at that information. The best way to think of it is as a 'thinking presence' in the environment. It's vector information that's being collected, not scalar information as found in other kinds of sensor networks." The harsh environmental conditions in Antarctica were ideal, because the ultimate goal is to put a similar Sensor Web on Mars to study the environment there and to react to it. "Antarctica was treated as an analog to Mars," Delin says.
"Part of the problem with searching for life on Mars," Delin continues, "is that the conditions for life aren't always present. We know from earth that sometimes the air temperature gets just right and you go into the sunlight, liquid water forms, and all of a sudden things bloom very quickly. It's hard to be there for that kind of event unless you put in place a sort of continual virtual presence. That's what the Sensor Web on Mars will be."
"Precision agriculture" Is another application for Sensor Webs, according to Delin. In this case, the Web both monitors the environment and controls it. "What you'd like to be able to do is leave sensors out in an agricultural environment, have them collect information about the environment, and then control things like irrigation," says Delin. "You can also imbue the Sensor Web with trending intelligence, so that [it will] know, say, that there needs to be no watering because conditions show that there is going to be rain. Or the Sensor Web might be able to tell that up the hill the soil gets more dry because water tends to run downhill." Delin's team has deployed a Sensor Web along these lines at Huntington Botanical Gardens in San Marino, California. "It's a virtual presence in the environment taking care of things, and it'll keep doing that even if you don't ever see any data coming out the back end," Delin adds.
That makes a Sensor Web different from, say, a mesh network. "Other sensor networks route information, and that's their focused goal," emphasizes Delin. "Sensor Webs collect information and interact with the environment based on what they detect. Much as intelligence in the brain results from the myriad connections among dendrites, the Sensor Web derives its functionality from a parallel-type architecture as sensor data are passed, and locally interpreted on the fly, from pod to pod."
Another application for Sensor Webs is sophisticated environmental control in buildings. And there is an aquatic deployment at the Kennedy Space Center. To find more information on all these applications and view real-time streaming data feeds from Sensor Webs at various locations, go to http://sensorwebs.jpl.nasa.gov/resources/applications.shtml. "Our team has been working on this for five years," says Delin. "We think its time has come."