No abstract

Two recent events have motivated a second look at estimates for the flux and mass of approximately micron‐radius interplanetary and interstellar dust observed by the twin STEREO spacecraft. First, the signals interpreted as nanometer dust impacts on STEREO‐A have nearly ceased, even though STEREO‐B continues to observe these signals unabated. Second, a recent laboratory dust accelerator experimental campaign has quantified the charge release associated with hypervelocity dust impacts on materials specific to STEREO. The first event enables an investigation of the extent to which nanometer dust signals influence estimates of micron‐radius dust flux. The second event allows an evaluation of how impact charge release values specific to STEREO materials influence dust mass estimates. Revised estimates based on these considerations yield higher fluxes and similar masses for micron‐radius interplanetary dust compared to prior studies, as well as lower fluxes and higher masses for interstellar micron‐radius dust compared to prior studies. The revised flux and mass estimates reported here differ by less than a factor of 4 from those reported in previous work, demonstrating that STEREO‐derived estimates for the flux and mass of micron‐radius dust are largely robust to spacecraft material charge yields and the disappearance of nanometer dust signals.

High‐velocity dust that impacts spacecraft releases charged plasma clouds that can create voltage perturbations that are measured by electric field instrumentation. These voltage perturbations are characterized by a relative maximum and minimum, which correspond to body and antenna charge recollection, respectively. The charge recollected by the antenna relative to the total recollected charge is found to correlate with the potential difference between the spacecraft and the antenna. From data analysis that spanned 2007–2013 on the STEREO‐A spacecraft, a positive correlation is found. This relationship will support future dust analysis with electric field instrumentation because it defines one spacecraft property that affects relative charge recollection.