Since the maintenance of the appropriate levels of oxygen is essential for ensuring the success of many of the specialized experiments in space missions, such as tissue culture experiments, the continuous monitoring of partial pressures of oxygen provides important data. We are developing optical methods of monitoring not only oxygen but also many dissolved constituents in blood and tissue culture solutions. The optical system uses tiny optical fibers, which easily fit inside a fine-gauged needle, for monitoring each specimen. Moreover, the beam can be split so that multiple specimens can be monitored simultaneously. The same optical technology can also be used for monitoring the blood chemistry of humans and animals; it is minimally invasive. It has a medical application for measuring tissue partial pressures of oxygen
