Technology Update: High-flying instrument helps scientists evaluate aircraft impacts.

A team at the Air Force Research Laboratory (AFRL), USA has developed an ultrasensitive mass spectrometer, with funding from US Government agencies. Atmospheric scientists are now using the instrument to analyse data giving the most detailed picture yet of military and space aircraft emissions. After they leave aircraft engines, the emissions begin to react chemically with each other and with the surrounding environment. The mass spectrometer can measure them at the part-per-trillion level, and take samples every 0.01sec. It has a uniquely excellent combination of sensitivity, time responsiveness, portability, and ruggedness. To capture aircraft emissions, its prototype was flown through aircraft contrails and exhaust plumes during over 100 flights conducted between 1995 and 1998 by the US Air Force and National Aeronautics and Space Administration (NASA). It was also used to make stratospheric measurements of Space Shuttle, Titan IV, and Delta rocket exhausts. The instrument is especially good at measuring very small concentrations of various acids. NASA plans to use some of the data collected to predict the future climatic effects of increasing the world's fleet of commercial supersonic aircraft, and find out whether subsonic aircraft increase cloudiness.