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.
Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas
Hypervelocity micro particles (mass < 1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (∼1028 m−3), but rapidly expand into the surrounding vacuum. We report the detection of radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity impacts of micro particles in ground-based experiments using micro particles that are 15 orders of magnitude less massive than previously observed. The EMP production is a stochastic process that is influenced by plasma turbulence such that the EMP detection rate that is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. In particular, impacts of the fastest micro particles occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. This new phenomenon may provide a source for unexplained RF measurements on spacecraft charged to high potentials.
The Inca Occupation of the South Coast of Peru
like the others, however; it forks into several nearly parallel ravines of which the largest are Huayuri, Rio Grande-Palpa, Ingenio (called Collao in ancient times), Nasca proper (the ancient Caxamarca), Taruga, and Poroma. Due to peculiarities of the local topography, the irrigated areas in Ica and the ravines of Nasca are located inland, at the foot of the mountains, rather than at the mouths of the rivers as is more usual in Peruvian coastal valleys. No sharp natural or cultural boundary separates the valley of Chincha from the valleys of Cafiete (ancient Huarco and Runahuana), Asia, and Mala, the next valleys going up the coast to the northwest. At the other end of the area we are considering, however, there is a sharp break; beyond Yauca the Andean foothills reach out to the sea, natural conditions are quite different, and there are important differences in the archaeological picture as well. The historical sources which mention the south coast are not particularly helpful, except in so far as they provide us with a few dates. To begin with, no chronicler gives an explicit account of the political organization of the south coast at the time it came into contact with the Incas. It can, perhaps, be inferred from Cabello Balboa's statements about common policy toward the Inca invaders that there was some sort of political connection between the valleys of Mala, Cafiete, and Chincha, but the connection need have been no more than a temporary military alliance. Cabello makes no mention at all of Pisco. The valleys of Ica, Nasca, and 125