Hydro Sphere products are based on Cosmic Ray Sensing (CRS) technology which was developed at the Hydrology Department of the University of Arizona in the early 2000’s. The earth experiences a flux of cosmic rays spanning its entire surface. These cosmic rays produce a shower of particles/secondary cosmic rays, as they collide with the atmosphere as they travel downward to the land surface.  These resultant secondary cosmic rays are sensitive to water in the environment, especially in the topsoil.  CRS instruments infer the amount of environmental water by measuring changes in the secondary cosmic ray flux.

The majority of traditional soil moisture sensors are ‘point sensors’ which are inserted into the ground and must be in direct contact with the soil. Through direct contact with the ground, point sensors measure physical quantities such as capacitance or dielectric constant to infer soil moisture. Often the accuracy of such sensors depends upon the quality of contact with the soil which can change over time. In every case, point sensors measure only a small volume of soil immediately around the sensor. In order to produce an accurate field average, a large number of probes must be distributed widely over the region to measure.

By contrast, CRS probes are non-contact probes (sitting above the soil), and measure soil moisture that is integrated and averaged over a wide area of the land surface, hundreds of meters in diameter. 

An additional and powerful benefit of the non-contacting nature of the CRS probe is that it can be used in a mobile platform to generate a soil moisture map as it continuously moves over the land surface.