NASA uses a heavily modified Douglas DC-8-72 as a flying science laboratory.
The aircraft, based at the NASA Dryden Flight Research Center, Edwards, Calif., collects data for many experiments in support of projects serving the world's scientific community. Data gathered by the DC-8 at flight altitude and by remote sensing have been used for scientific studies in archaeology, ecology, geography, hydrology, meteorology, oceanography,
volcanology, atmospheric chemistry, soil science and biology. The DC-8 also flies sensor development and satellite sensor verification missions.
The aircraft can carry 30,000 pounds of scientific instruments and equipment.
Among the aircraft's features are wing pylons (for aerosol sampling), a gyro-stabilized pointing and tracking mirror system, a dropsonde delivery tube, atmospheric chemistry sampling probes, and several reinforced ports that accept experiments pointing in virtually any direction.
Photo source: http://www.dfrc.nasa.gov/Gallery/Photo/DC-8/HTML/EC00-0050-1.html