In order to gain confidence in the science we do, we desire to make inspections of the results. If the validation team confirms the dust, cloud, and land surface measurements made by MISR, the science community has assurance it is safe to use this information for their own needs.
The validation staff perform their services by maintaining a collection of instruments which measure dust, and surface-reflected light. We call these instruments the "field instruments", as they are taken to Earth locations outside of our office locations. Some examples of field sites are desert locations, cities, ocean areas, and vegetated land surfaces (both natural and agricultural). The measurement taken at these sites are compared directly against the same measurements made by MISR, from space.
This picture shows members of the MISR validation team. They are working at a desert site, and have in front of them an instrument which measures the light coming from Earth's surface. Desert sites are one of several different types of sites used to calibrate the measurements made by MISR.