Solar energetic particles (SEPs) are a type of space weather that can pose a threat to astronauts and spacecraft. They are high-energy charged particles that are ejected from the Sun during solar flares and coronal mass ejections (CMEs). SEPs can travel at speeds of up to several million miles per hour and can be harmful to both people and equipment.
Astronauts on missions outside of Earth’s protective magnetosphere are at risk of being exposed to SEPs. The International Space Station has special shielding to protect the crew from SEP events, but even so, astronauts have been known to experience short-term health effects from exposure to SEPs. In extreme cases, SEP events can damage or destroy satellites and other spacecraft.
There are two main types of solar energetic particles: protons and electrons. Protons make up the majority of an SEP event, while electrons make up a smaller percentage. Both types of particles can cause harm, but protons are more dangerous because they are heavier and have a higher energy level. Electrons typically pose a greater threat to electronic equipment than they do to people.
Solar energetic particle events are caused by eruptions on the Sun’s surface, such as solar flares and coronal mass ejections. These eruptions release large amounts of radiation and particles into space. The particles then travel outward from the Sun until they encounter something in their path, such as Earth’s magnetic field or a spacecraft.
When an SEP event is heading toward Earth, it can interact with our planet’s magnetic field in one of two ways: it can either be deflected away from us or it can enter into Earth’s atmosphere. If an SEP event is large enough and/or close enough to Earth, some of the particles will eventually reach our planet’s surface where they can cause problems for both people and technology alike.