Among these are gravity, seismic, and electrical methods. The hunt seems to call for straightforward research, progressing until the problem is solved. But investigative science, like the plots of detective novels, is often punctuated by the unexpected. In this case, a promising approach being investigated for detecting permafrost depends on changes in the electrical properties of soil caused by the presence of frozen water. Some devices that detect these changes are small enough to be carried by one person.
Field testing is the approved way to tell which technique and which device works best.
To provide a valid test for techniques and equipment, and realistic training for operators, they excavated a pit, measured it, filled it part way with water, and let winter do the freezing. Then they buried it with the excavated soil and tamped the whole thing down. The pit lay in a seldom-used corner of the university farm. The location provided a natural landscape and the realism of nearby powerlines and passing vehicles to challenge the sensitivity of detectors. It was also conveniently close to the institute, and in a fenced area protected from passersby.