Plasma density fluctuations observed during space shuttle orbiter water releases

Observations by the Langmuir probe on the Plasma Diagnostics Package flown as part of the Spacelab 2 mission in the summer of 1985 show a strong increase in the level of turbulence near the shuttle orbiter during operations in which liquid water is released. The spectrum of the plasma density fluctuations peaks at the lowest frequencies measured (a few hertz) and extends up to a few kilohertz, near the lower hybrid frequency. The authors suggest two potential mechanisms for generating the plasma turbulence which are both based on the production of water ions as a result of charge exchange with the ambient oxygen ions in the ionosphere. The first mechanism proposed is the ion-plasma instability which arises from the drift of the contaminant ions with respect to the ambient oxygen ions. The other mechanism proposed is the Ott-Farley instability which is a result of the ring distribution formed by the pick-up water ions