How would a coronal mass ejection (CME) affect the ISS?
Today we have several satellites that monitor the Sun and the local space environment, so we would have warning if a CME occurred to prepare ourselves both on Earth and on the International Space Station (ISS). Sometimes CMEs can cause ‘solar particle events’ where energetic protons and other nuclei are emitted by the Sun. Energetic particle irradiation may cause electronic errors, so during the CME event the ISS could choose to be electronically quiet to avoid computer glitches. Fortunately the electronics on spacecraft are designed to withstand particle irradiation. The silicon-cell solar panels of the ISS are glass-coated and would probably survive unscathed.
Most of the harmful radiation that astronauts on the ISS experience is from the higher energy but less abundant galactic cosmic rays and the Van Allen belts of trapped particles. In a large solar particle event, astronauts can receive a significant dose of radiation from these highenergy protons over a few days.
A superstorm-like CME event may have another effect. X-rays from the event may deposit enough energy in Earth’s atmosphere for it to expand. This would cause increased drag on satellites orbiting below about 600 kilometres (370 miles). The ISS orbits at roughly 400 kilometres (250 miles) altitude. The ISS uses rockets from attached spacecraft periodically to boost its orbit, so it may need an extra boost.