We've been hard at work on the next phase of this project. We've installed a capacitive moisture detector in the egg sensor, changed from 8 AA NiMH batteries to 3 AAAs, added a solar cell that keeps the batteries charged up until they totally die (about 10 years?), and changed the connection between the sensors and the communications tower to a single RG6 coax cable. The coax will power the sensors and also carry data. A single communications tower will be able to handle multiple sensors simultaneously (we're not sure how many yet, but it should be about a couple dozen). The coax should be much more reliable than the Cat5 cable we have been using, and make it easier and cheaper to build and maintain. A coax cable can be repaired in the field in about a minute. There will be lots of ways to extend the system using SPI, I2C, and analogue and digital connections. Software will be field updatable, and we've been working on server-side visualization of the data. For more information about our progress, please visit http://turtlesense.org.
The National Park Service has been using the system this summer with excellent results. One sensor failed, but every other nest has provided data that was used to accurately predict when baby sea turtles would emerge from their nests. Most of our predictions were about 4-5 days before emergence, and the prediction was usually correct within a day. We were able to spot nests that were infertile, and were only incorrect when we predicted an infertile nest, but in fact less than 10 percent of the eggs hatched. While we missed that handful of hatchlings, the NPS was able to rescue about 75 hatchlings from almost certain drowning because of our system. We knew that they had hatched, but they hadn't yet emerged. A storm and high tide threatened to drown the hatchlings who were trapped in the nest with a hard crust above it. Because the NPS knew from our system that there were hatchlings, they were able to rescue them just in time.