As it orbits the earth, the space station is virtually unprotected from the ravages of extreme solar storms. There are three primary ways the electrical systems on board the station may be affected. First, certain electromagnetic energies from the sun may lower the electrical production of the solar arrays. On January 17, during the last solar storm, the PV arrays were only able to generate 45% of their potential electrical power. Fortunately, this decrease in efficiency was temporary.

Secondly, solar storms affect computers. Integrated circuits, or computer chips, in the space station are vulnerable. Intense electromagnetic energy penetrates the electrical circuitry of a microchip and can cause the logic registers to "flip their bits". When this happens the registers in a binary logic chip are reversed. A binary logic chip registers either ones or zeros. All computer languages are based upon combinations of ones and zeroes. If the ones and zeros in the computer's registers are reversed, the computer’s programs crash. If the computer operating software becomes scrambled, the crew must go to manual control until new software can be uploaded.

Third, electrical circuits can become permanently damaged by intense electromagnetic surges. In this case, circuitry can literally fuse together as the small conductors melt. This occasionally happens on earth in northern power stations, or to satellites.

To protect against these emergency situations, NASA has developed ways to "harden" or shield the electronic components from dangerous solar energy levels. They have done their best to brace the space station against the flood of X-rays and gamma rays during solar proton events. However, shielding is not 100% effective, and radiation can still penetrate the systems.

The intensity and duration of a future solar storm could damage the space station's power systems or controls. Computers control practically every electromechanical device on the station. If the data one computer sends to other computers becomes contaminated with flipped bits, the systems could crash. This is what happened on January 17 when the Environmental Control and Life Support Systems malfunctioned. Computer technicians believe that the new software has since corrected the problem. However, another solar storm may prove them wrong.

Emergency Procedures
If the space station were to experience a power emergency, the astronauts must first identify the problem. Once the problem has been identified, corrective measures must be taken.

Conserving battery power is essential if the power from the solar arrays drops. The space station’s designers have determined that PV array power production should fall below 50%. If the battery reserve power levels approach 50% of capacity, steps must be taken to reduce the total power draw of the space station. The operational levels of individual electric circuits can be reduced to conserve battery power. The astronauts can "weather the storm" until the photovoltaic arrays return to normal operation by selectively controlling the amount of power that is delivered throughout the station. Lights could be dimmed and non-critical devices could be temporarily shut down. Oxygen and electricity would be conserved by evacuating and closing down entire modules.

Procedures have been established to govern the amount of power reduction each of the systems can tolerate and the order in which equipment should be turned off. The electric power used to conduct experiments and to run systems not critical for life support and astronaut safety is the first to be cut back or completely turned off. Each of the other support systems should be shut down in a sequence that maintains safety and station control. The design engineers for each of the systems aboard the space station established the absolute minimum power requirements and operating levels during emergencies.