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Space Environment Effects and Interactions

All information is from NASA Research Centers.

The Plasma Environment near an orbiting spacecraft depends on where it is located in the natural plasma environment, and on its own gaseous products. Interactions between the spacecraft and the plasma include arcing, current collection, and system and material charging.

Arcing removes surface dielectic or insulating material, exposing underlying conductors to the plasma and providing sites for current collection with power loss and electromagnetic noise. Arcs may also cause logic upsets which result in operational anomalies. Arcing also removes portions of atomic oxygen protective layers, exposing surfaces to errosion. When a defect occurs, atomic oxygen undercuts the remaining surface protection resulting in damaged areas larger than that of the defect alone.

Plasmas and/or Gaseous Products resulting from spacecraft operations interfere with scientific instruments by altering optical properties, producing optical interference or EMI (Electromagnetic Interference), altering spacecraft protentials, all of which compromise data.

Ion sputtering removes surface atomic or molecular species by ion bombardment, The species removed by sputtering may be redeposited at other sites producing unwanted contamination, or altering surface electrical/optical properties.

The Neutral Environment present at Low Earth Orbit also presents some effects such as atomic oxygen degredation that may harmfully impact a spacecraft. Atomic Oxygen Degredation is a chemical interaction between atomic oxygen and certain materials that can cause changes in the material's surface properties and/or physical degredation of the material.

Surface contamination created by outgassing materials or deposition of spacecraft effluents can coat sensitive surfaces such as optical sensors.

The Radiation Environment may cause Single Event Upset and degrade solar array surfaces and cells, electronic components and sensors and dielectric materials. It can also deposit charge inside dielectric materials and on surfaces internal to the spacecraft. Such charge deposition can result in dielectic breakdown and EMI electrical upsets.

The Micrometeoroid or man-made Orbital Debris Environments can impact and physically damage a spacecraft. These impacts can also stimulate arc discharges in regions of electrical stress.

These interactions are important to spacecraft designers. They are a cause of spacecraft system and subsystem damage and/or degredation, electrical power loss, material property degredation, payload interference, and electrostatically enhanced contamination.

Mitigation strategies in spacecraft design include selection of proper materials, design of payload and power system geometries to minimize exposure to high voltage surface areas, choice of operating voltages to remain below arc thresholds, design of spacecraft grounding to keep sensitive spacecraft structures near the plasma electrical potential, and using plasma contractors to maintain spacecraft potential.

Marvin Ostrega

Systems Design Tech Committee

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