Electrical anomalies on spacecraft due to hypervelocity impacts
One of the main challenges in satellite design is dealing with the threat from the space environment. Numerous spacecraft anomalies are reported on a regular basis and in most of these cases, it is extremely difficult to diagnose the cause of these anomalies/failures. Hypervelocity impacts from meteoroids and orbital debris has recently emerged as possible catalysts for electrical anomalies observed on spacecraft. In this paper, we present a case study and statistical analysis of hypervelocity impact-induced electrical anomalies. We present data showing anomalous currents in the power distribution system on the JASON-1 satellite following a hypervelocity impact. A statistical analysis is carried out using 2413 anomalies from the Ascend satellite anomaly database and 5033 anomalies from the anomaly database maintained in the 1990s by the National Geophysical Data Center (NGDC). We find that there is no correlation between the flux of shower meteoroids and incidence of anomalies. For geostationary satellites, we use NASA's Meteoroid Engineering Model to calculate the flux of sporadic meteoroids at different locations in the orbit and find that the incidence rate of anomalies is significantly higher in regions with high average meteoroid flux. These results serve as a strong indicator of electrical damage caused by electromagnetic emissions from meteoroid impacts.
Theory and experiments characterizing hypervelocity impact plasmas on biased spacecraft materials
Space weather including solar activity and background plasma sets up spacecraft conditions that can magnify the threat from hypervelocity impacts. Hypervelocity impactors include both meteoroids, traveling between 11 and 72 km/s, and orbital debris, with typical impact speeds of 10 km/s. When an impactor encounters a spacecraft, its kinetic energy is converted over a very short timescale into energy of vaporization and ionization, resulting in a small, dense plasma. This plasma can produce radio frequency (RF) emission, causing electrical anomalies within the spacecraft. In order to study this phenomenon, we conducted ground-based experiments to study hypervelocity impact plasmas using a Van de Graaff dust accelerator. Iron projectiles ranging from 10−16 g to 10−11 g were fired at speeds of up to 70 km/s into a variety of target materials under a range of surface charging conditions representative of space weather effects. Impact plasmas associated with bare metal targets as well as spacecraft materials w...
A mechanism for the production of electromagnetic radiation during fracture of brittle materials
The feasibility of the charge separation model as the source of electromagnetic radiation received from the fracture of brittle materials is demonstrated. An analytical expression and a finite difference method enable the calculation of currents flowing around the tip of a crack. Results from the model compare favourably with fracture events recorded from ice samples. Changes in material conductivity affect pulse shape although changes in crack surface conductance and not crack apex conductance cause most variation in the received signal.