Scientists are aware of the damage that solar storms
can cause to the space station's sensitive electrical systems. They have
designed the space station with several safety features. Many of these features
help conserve electrical energy during solar storms. Other special devices
have been designed to gather and remove static electricity- excessive amounts
of electrons that build-up in the lining and on the surface of the space
As it orbits the Earth, the space station is basically unprotected from the ravages of solar storms. There are two primary ways the electrical systems on board the station may be affected. First, the electromagnetic energy from the sun could cause the solar arrays to work less effectively. Research has shown that PV arrays subjected to enough radiation can diminish in their capacity to generate power. On January 17th when the last storm occurred, this effect was only temporary, but the PV arrays were only able to generate power at 45% of full capacity.
The second way solar storms affect electrical systems
is in the computers and wires themselves. Integrated circuits, or computer
chips, in the space station are vulnerable to certain kinds of solar weather.
Electromagnetic energy can penetrate the electrical circuitry of a microchip
and cause the logic registers to "flip their bits". This means
that the memory registers in a binary logic chip can be reversed. "Bi"
means two. Binary means that this particular chip can register either
"1's" or "0's." All computer languages are based upon
combinations of 1's and 0's. If the ones and zeros in the computer's software
codes are reversed, the computer's program can become unstable or not
work at all. In the same way, if the computer software that runs the space
station's power system or life support system becomes scrambled, the crew
must go to manual control until new software can be uploaded.
If the space station were to experience a power emergency the astronauts first must identify the problem. Once the problem has been identified corrective measures must then be followed.
If the output of the solar arrays is diminished and the ability to generate power is reduced the conservation of remaining battery power is essential. The designers of the space station have determined that a 50% total power reduction is a critical value not to fall below. If the reserve power levels approach 50% of capacity, steps must be taken to reduce the total power draw of the space station. That is, the operational levels of individual electric power consuming systems can be reduced to conserve battery power. The astronauts can selectively control the amount of power that is delivered throughout the space station, within specified limits, to "weather the storm" until the PV arrays return to normal operation. For example, the lights could be dimmed, any device not critical could be shut down and entire modules could be evacuated eliminating the need to generate light, heating, cooling and breathable oxygen.
There are procedures governing the amount of reduction each of the systems can tolerate. The electric power to conduct experiments and anything not critical to support life and guarantee safety is the first to be reduced or completely turned off. Each of the other support systems is to be reduced in a sequence that will maintain safety and station control. The absolute minimum power requirements and operating levels have been established by the design engineers for each of the systems aboard the station.