Detection of High Voltage Spacecraft Charging

Proposal Summary

Award Period:


We propose to design and construct a prototype of a low cost hand-held instrument that will be convenient to use and will enable EVA astronauts to measure exposed high voltages and surface electrical charge density on nearby spacecraft components. This measurement mitigate the risk of electrical discharge hazards. This instrument will be particularly useful for applications associated with the International Space Station (ISS), and also has applications in the Shuttle environment. The proposed double probe instrument will have the following applications:

  1. Diagnosis of regions where the electrical shielding of ISS power conduits has broken down owing to erosion by ionospheric atomic oxygen bombardment, to holes produced by micrometeoroid impact, or to unscheduled erosion events produced by other human activities.
  2. Detection of hazardous electrostatic potentials on exterior spacecraft dielectric materials owing to the presence of high voltage electrical systems within the ISS structure.
  3. Detection of hazardous electrostatic potentials and/or large surface charges on spacecraft structures and materials owing to auroral precipitation.
  4. Scientific study of both the electric surface charges that may build up on wake facing dielectric surfaces and the electric fields present within the plasma wake of large structures in space. Such studies could easily be included on a low cost/low impact basis within the framework of a variety of other activities.
In view of the possible hazard that large surface charges represent, and in view of the scientific interest that exists in understanding the plasma environment and surface charging of both the Shuttle orbiter and the Space Station, a feasibility study of a hand-held Langmuir double probe has been conducted [Armstrong, 1993]. A design methodology based on the probe model of Fahleson [1967] was adopted. It was found that a probe system could be built that would operate successfully in the very low plasma density environment of the ISS and Shuttle wakes and still be carried and operated by a single EVA crewperson. This proposal requests support for the design and construction of a prototype which can then be tested in ground-based plasma chambers here in Houston.

A related publication is ``A Sounding Rocket Observation of an Apparent Wake Generated Parallel Electric Field," E. A. Bering III, J. Geophys. Res., 88, 961-979 [1983].