The Sun does not only provide power to satellites. Its activity also creates one of the main operational risks in orbit. Space weather, the changing conditions in space driven by solar activity, can disturb electronics, degrade communications and even pull satellites out of orbit. This guide explains the main phenomena and their effects.
What drives space weather
- Solar flares: sudden bursts of radiation from the Sun that can disturb radio communications on the day side of the Earth within minutes.
- Solar energetic particles: high energy protons accelerated by flares and eruptions, which can cause radiation storms in space.
- Coronal mass ejections: large clouds of magnetised plasma that can trigger geomagnetic storms when they reach the Earth, usually one to several days after leaving the Sun.
Effects on satellites
- Single event effects: energetic particles can flip bits in memory or disrupt electronic components.
- Surface and internal charging: charged particles can build up on or inside a spacecraft and cause damaging discharges.
- Atmospheric drag: geomagnetic storms heat and expand the upper atmosphere, which increases drag on satellites in low orbits. Newly launched satellites in very low deployment orbits are especially sensitive.
- Communication and navigation: disturbances in the ionosphere can degrade radio links and satellite navigation signals.
Forecasts and warnings
In the United States, the NOAA Space Weather Prediction Center issues forecasts, watches and warnings and classifies events on scales for radio blackouts, solar radiation storms and geomagnetic storms. Operators can use these alerts to postpone critical manoeuvres, put sensitive instruments into safe modes or adjust deployment plans.
What operators can do
- Design electronics with radiation tolerance and error correction suited to the orbit.
- Plan deployment altitudes with margin for periods of high solar activity.
- Include space weather monitoring in operational procedures.
Related reading
- Space Situational Awareness: How Satellites Avoid Collisions
- Swift Boost Mission Ends Without Reboost: Lessons for In-Space Servicing
- Satellite End of Life: Deorbiting, Graveyard Orbits and Passivation
Sources
Cover image: A significant solar flare observed by NASA's Solar Dynamics Observatory. Credit: NASA/SDO (GSFC_20171208_Archive_e001210), public domain.