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Spacecraft Operation Services

Spacecraft operations are by nature complex and every satellite's operational environment poses a range of potential risks, often a unique combination for a given orbit.  The implications of interruptions of operations, data transfer and service provision, are serious, both in terms of cost and capability, thus it is imperative to mitigate against all operational risks to the fullest possible extent.

In Orbit Environment and Effects Monitoring Provides a near real-time estimate of the environment and its effects actually experienced.
Post-event analysis Under development.
In-orbit environment and effects forecast Under development.
Mission risk analysis Under development.
Space Weather in the Solar System Provides forecasts, nowcasts and alerts of heliospheric weather phenomena in order to support solar system mission operators.

Spacecraft Operation Background

The effects of space environmental factors must be considered on an event-by-event basis during the operations phase. For example, cosmic rays (GCRs) and solar energetic particles (SEPs) are known causes of single event upsets (SEUs) such as latch-ups in onboard electronics systems, often resulting in instruments and potentially platforms automatically going into safe mode. In the worst case, this can result in terminal damage. SEP events can disrupt telecommanding and data telemetry as a result of the interference in data systems, and the data itself is often worthless due to high levels of noise. Trapped radiation in the radiation belts leads to degradation of components as a result of prolonged dose, with processors, detectors and solar cells particularly vulnerable. A satellite passing through energetic charged plasma will experience a range of charging effects, both on the surfaces and internally within electrical systems, and these charge differentials can lead to sudden discharges and subsequent failure of electrical systems. Less energetic plasma also poses problems, with discharge and sputtering often leading to secondary electron emission and subsequent associated charging problems. Even the neutral atmosphere can be hazardous, with neutral atomic oxygen known to lead to surface erosion of the platform materials, potentially compromising the surface and leading to surface charging. A greater risk to surface integrity comes in the form of debris and micro-meteoroids which can compromise and puncture materials due to their high kinetic and potential energies.

© M. A. Shea, Geophysics Dir., Philips Laboratory

Correlation between the distribution of memory upsets experienced by a satellite in Low-Earth orbit and of energetic protons over the South Atlantic Anomaly. Left figure shows where memory upsets occured onboard the British UOSAT-2 satellite launched into a 700 km sun-synchronous orbit in March 1984. The right hand Figure shows the flux of protons with energy greater than 10 MeV at 500 km altitude based on the NASA model AP-8 MAX.

Some examples of Space Weather data used on a routine basis within mission operations are the forecasts and nowcasts of: solar flares, solar and magnetospheric energetic particle fluxes, geomagnetic storms, and total electron content.  These products based on measured data and modelling are known to be linked with effects such as radio frequency interference, SEUs/latch-ups, radiation damage, charging, and telemetry signal degradation.