By Josh Rhoten
Key takeaways
- Researchers are experimenting with a mobile sensor that uses cosmic rays to measure soil moisture content for use in hydrology work.
- The sensor, called a cosmic ray neutron rover, can provide useful data for the management of landscapes after wildfires.
What can tiny, highly charged particles arriving on Earth from outer space tell us about soil moisture content within wildfire burn scars in Colorado and Wyoming?
Quite a lot, as it turns out.
Colorado State University civil engineers are testing the capabilities of a cosmic ray neutron rover to evaluate soil moisture across a variety of situations. Their ongoing work to further develop this mobile sensing technology may be useful in assessing long-term hydrological changes from wildfires such as increased erosion or changes to soil composition. The tool may also be particularly useful to measure changes to snowpack levels that occur due to increased sun exposure after fires and are key factors in seasonal runoff levels.
Cosmic rays are a type of radiation that travels through space at the speed of light. Scientists believe these particles originate from powerful events, such as supernovas and solar flares. They often travel long distances before arriving on Earth, where they then mostly glance harmlessly off our atmosphere. However, when the cosmic rays do make it through that protective layer, they scatter and create a shower of secondary particles – thousands of which pass through us every day with no problem.
A key byproduct of this scattering process is the creation of high-energy neutrons. These newly formed subatomic particles then interact with the hydrogen commonly found in our soils, Jeffrey Niemann, a professor in CSU’s Department of Civil and Environmental Engineering, said.
“Hydrogen atoms are very effective at slowing down and absorbing the energy of neutrons,” he said. “Because hydrogen in the environment is often contained in soil moisture, wet soils reduce the number of neutrons that occur in a certain energy range, while dry soils allow more of those neutrons to be detected. Measuring those differences allows us to estimate soil moisture across entire fields instead of at just a single point.”
Stationary versions of these types of cosmic ray sensors have been used in agricultural research for more than a decade. They can passively monitor an area about once an hour.
Source : colostate.edu