How does the crew on International Space Station shelter themselves when there is a geomagnetic storm?

We are currently experiencing a G4 Severe Geomagnetic storm resulting from a solar coronal mass ejection which occurred on 18 January 2026. Read that crew on the ISS had taken shelter to protect themselves during the ongoing geomagnetic storm. When a significant geomagnetic storm or solar particle event occurs, the crew of the International Space Station (ISS) follows a protocol designed to minimize their radiation exposure. While the Earth’s magnetosphere provides a natural shield for the station, severe storms can cause “holes” or regions where radiation levels exceed safe baselines. The primary strategy is to move the crew to the most heavily shielded areas of the station, known as “safe havens.”

1. Hardened Safe Havens

The crew typically shelters in two specific modules that offer the highest density of protective material:

• The Zvezda Service Module (Russian Segment): This is the most frequently used shelter. During its construction, it was lined with specialized polyethylene (a hydrogen-rich plastic) shields. Hydrogen is exceptionally effective at slowing down and absorbing high-energy protons.
• The US Lab (Destiny): This module is also considered a safe haven because it is located in the center of the station’s main cluster. Being surrounded by other modules provides “geometric shielding,” where the other station components act as extra layers of mass.

2. Utilizing “Water Walls”

Water is one of the best radiation shields available because of its high hydrogen content. The crew may be instructed to:

• Move water storage containers and food supplies to the walls of their sleeping quarters or the safe haven modules.
• By lining the walls with these dense, hydrogen-rich items, they create a temporary, thick “shield” that significantly reduces the amount of radiation reaching their bodies.

3. Personal Protection (AstroRad Vests)

In recent years, NASA has tested specialized wearable technology like the AstroRad vest. These are selective shielding vests designed to protect the most radiation-sensitive organs (like bone marrow and the gastrointestinal tract) while allowing astronauts to remain somewhat mobile if they need to perform essential tasks during a storm. These vests use high-density polymers. They are often described as “gravity blankets” and can be worn even while inside a safe haven for double protection.

4. Operational Protocols

The ground-based Space Radiation Analysis Group (SRAG) at Mission Control monitors solar activity 24/7. When a storm is detected:

• EVA Suspension: All spacewalks (EVAs) are immediately canceled or terminated. An astronaut in a spacesuit has almost no protection compared to someone inside the station.
• Sleep Relocation: If a storm is expected to last through the “night,” the crew may be ordered to sleep in the more protected modules rather than their individual crew quarters.
• Orbital Avoidance: Ground teams monitor the station’s position relative to the South Atlantic Anomaly (SAA) and the polar regions, where radiation is highest. The crew may be told to avoid certain “thinly shielded” modules (like the Cupola or the Node 3 gym) when passing through these high-risk zones.
• Real-time Monitoring: Crew members wear Active Dosimeters that provide real-time data via Bluetooth to Mission Control, allowing doctors to track each astronaut’s cumulative dose throughout the storm. While a typical day on the ISS might expose an astronaut to about 0.5 to 1 mSv of radiation (roughly equivalent to 50–100 chest X-rays), severe storms like the one which we are having now, can spike those levels significantly within hours. Astronauts are currently witnessing some of the most spectacular auroras ever recorded from orbit, as the “auroral oval” has expanded significantly toward the equator.
• Altitude Maneuvers: While rare, mission control can sometimes adjust the station’s orientation to ensure the most shielded parts of the station are facing the direction of the incoming particle flux.

Summary of Shielding Materials

Material	Why it is used	Effectiveness
Polyethylene	High hydrogen density; light for launch.	Very High (Standard in Zvezda)
Water/Food	Dual-purpose; high hydrogen content.	High (Used for “Water Walls”)
Aluminum	Primary hull material.	Low (Provides basic structure but can create secondary radiation)