Flux measurements of trace gases and other quantities, such as latent heat, are of great importance in scientific field research. One typical flux measurement setup involves placing measurement equipment (sonic anemometers and associated sensors or samplers) on rigid towers (rigidity being required to provide a stable platform for the sonic anemometers). These towers are relatively immobile, and cannot be readily moved nor installed in remote locations. This prevents fluxes or vertical profiles of trace species from being measured in many remote areas. Anasphere will develop a tethersonde system which will allow flux measurements to be made using tethered blimps or kites. The tethersonde modules will incorporate a three-dimensional sonic anemometer plus motion-correction sensors so that the motion of the tether and module may be removed from the wind measured by the sonic anemometer. The result will be a highly mobile flux tower. In Phase I, a proof-of-concept tethersonde module will be built and tested which incorporates a three-dimensional sonic anemometer and motion-correction sensors. It will be tested in flight. Phase II work will see the refinement of the modules and sensor algorithms, as well as extensive field tests.