Mini-Sniffer research. Researchers wearing self-contained suits while testing a model of the Mini-Sniffer III atmospheric sampling aircraft. The Mini-Sniffer is a remotely controlled, propeller-driven aircraft that was developed for sampling pollutants at altitudes above 24,380 metres (80,000 feet). This model is using hydrazine as its fuel. Hydrazine is a highly hazardous material, so those who are to come in contact with it must wear protective clothing to prevent contamination. The Mini-Sniffer has also been considered for exploring the atmosphere of Mars, where the gravity is 38 per cent of that on Earth, thus reducing the power needed for flight. Photographed in 1976 at NASA's Drysden Flight Research Centre in California, USA.