Indium-Tin Oxide-Coated Glass for Passive Ion Collection on Small-Scale Spacecraft

A small-scale spacecraft has limited resources and requires innovative solutions to enable capabilities similar to those of a larger spacecraft. In particular, a small-scale spacecraft has a limited outer surface area, which is typically used for body-mounted solar panels, yet may be required for passive ion collection when in situ plasma measurements are conducted. We present the results of ground-based experiments demonstrating that indium-tin oxide-coated glass is effective as a dual-purpose material for facilitating solar panel operation (due to its transparency and resistance to atomic oxygen degradation) as well as for passive ion collection (due to its surface conductivity). The test facilities utilize a plasma-generating device that produces a low earth orbit-like environment within a vacuum chamber. We used physical vapor deposition to apply gold contact patches to make electrical connections from the indium-tin oxide-coated glass to the spacecraft. The results indicate that the materials with relatively high work functions collect less current from the plasma environment than the materials with relatively lower work functions. The resultant contact potential difference generated from the disparate work functions can be used to further mitigate spacecraft charging.