The KC-135 is a NASA airplane which provides a special opportunity to perform experiments in microgravity. The plane flies in parabolas, resulting in 2-g during the pullout, and 0-g for a period of 25-30 seconds over the top. The plane is used for 0-g experiments, as well as for astronaut training. A typical week of flying will be 40 parabolas a day, four flights per week. To those who have experienced the thrill of floating, the KC-135 is fondly known as the "Vomit Comet."
The UCSD Physiology/NASA lab has conducted several experiments aboard the KC-135 plane.
From the four aerosol sizes studied in the first set of flights, the 1-micron size was chosen based on its medium range of deposition. For the next set of flights, the subject inhaled a full breath from residual volume (out as far as he or she can go) all the way up to total lung capacity (up as far as he or she can go). A bolus (small volume) of aerosol was inserted by the valve system into the breathed air at different times in the inspiration (one bolus per test). The subject then exhaled back out to residual volume, and the deposition was seen to change depending on how early in the inspiration the aerosol was introduced. The data from the flights will be compared to data taken on each subject on the ground, to see how aerosol deposition changes in 0-g and 2-g compared to 1-g.
See the Publications for some of the published results from these experiments.