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WHITE PAPER Advancing Signal and Data Processing for Space Payloads mrcy.com 4 ELECTROMAGNETIC RADIATION AND OTHER ENVIRONMENTAL COMPLEXITIES The space domain's benefits are clear and unmatched, but it comes with environmental factors and obstacles that developers of earthbound technology do not face. This, combined with the same ever-evolving requirements and user demands seen in the commercial and defense worlds, has created the need for technology that is fast, small, low power, reliable, cost-efficient, and durable. The following sections discuss and examine these environmental difficulties. • Signal saturation and the space-link-ground triad Satellites are not always in constant communication with their network or ground stations. For example, signal saturation, or the overuse of certain available frequency bands, can result in desired bandwidths and the ability to downlink being available only at certain times. The space-link-ground triad of communication can also cause the same issue because transmitters and receivers are not always within range of each other. To counteract this inability to transmit data— whatever the cause—extraordinarily reliable and radiation-tolerant data storage hardware is required to keep the data secure and accurate until the transmission is possible. • Non-feasibility of fixing or upgrading existing satellites Open architecture and modular hardware designs allow for the use of COTS parts and reduce the time and cost it takes to develop systems for all domains. Another advantage they typically bring is the ability to physically replace electronics and other subsystems with newer and more advanced plug-and-play parts. However, upgrading or fixing existing satellites in this manner is not feasible. That is because performing such a procedure in the space domain on a vehicle like a satellite— for example, the five spacewalks undertaken to fix the Hubble Space Telescope—is an extremely complicated and expensive task reserved for the most important and expensive missions. Therefore, the space components must work the first time and every time throughout the satellite's operational life. • Dangers of space junk and other material Electromagnetic radiation and other light and energy sources are not the only environmental threat. LEO space junk, comprising material from previously functioning vehicles like satellites and from naturally occurring objects such as micrometeoroids and orbital debris (MMOD), can stay in low Earth orbit from 5 to 400 years. They can also range in size from a school bus to a grain of sand, collide with each other to create more debris, and result in extreme damage when making contact with an object while traveling at hypervelocity speeds as high as 7.7 km/s. This means shielding on space vehicles and even astronaut suits are not limited to just antiradiation requirements; it must also protect against extreme physical impacts. • Solar flares and electromagnetic radiation Space vehicles and their electronics are continuously subject to radiation in the form of waves or small subatomic par ticles, the latter of which is of a par ticular concern to spacecraft. Subatomic par ticle radiation, which includes protons and electrons, and other radiation can cause issues with space-based systems in several ways: — Single-event upset A single-event upset, or SEU, is caused by a single ionizing particle, such as ions, electrons, or photons, that strikes sensitive areas of a microelectronic device. This free charge creates a state change and can directly change data; for example, it can change a one to a zero or vice versa in computer code, which is also called a bit flip. Although this soft error does not cause permanent damage to electronics, radiation environment electronics must include advanced error correction code algorithms to counteract the issue. — Single-event effects Other single-event effects (SEEs) include single-event latch-ups (SELs), a short circuit that can occur in a silicon chip that requires a power cycle to correct; a single- event gate rupture (SEGR), where a single particle strike results in a breakdown and subsequent conducting path to the gate oxide of a metal oxide semiconductor field effect transistor (MOSFET); and a single-event burnout (SEB), where a particle strike induces a high current state, resulting in catastrophic failure. There are also instances where particles will erode a component over time, leading to its eventual failure. — Geomagnetic storms Large geomagnetic storms caused by the sun have the potential to heavily damage not only space vehicle electronics but also those across the globe. Take, for example, the Carrington Event of 1859, the most intense geomagnetic storm in recorded history. Auroras were seen around the world, including at the equator, and telegraph equipment sparked, caught on fire, or maintained an electrical charge even after being disconnected from the grid. It is estimated that a storm of this magnitude today would cause worldwide blackouts or widespread electrical disruptions as well as global infrastructure and personal property damage.

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