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Teacher Lesson Pages
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 station.
As it orbits 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 when PV (photovoltaic) arrays, or huge solar
panels, are subjected to enough radiation they can become less able to generate power. On Jan. 17 when the last storm
occurred, this effect was only temporary, but the PV arrays were only able to generate power at 45 percent 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 them to "flip their bits." This means that the memory in the binary 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.
These facts have led NASA to develop ways to "harden," or shield, the electronic components from dangerous solar energy levels.
Scientists have done their very best to harden the space station against solar proton events, X-rays, and gamma rays. However,
shielding is not 100 percent effective, and radiation can still penetrate. If the intensity and duration of a future solar
storm are enough, the storm can damage the space station's power systems or controls. If this happens, huge problems could occur
aboard the station.
Multiple computers control practically every electromechanical device on the space station. If the data from one computer
"talking" to other computers or controls becomes contaminated with flipped bits, it could cause a malfunction in the systems.
This is what happened on Jan. 17 when the environmental control and life support systems malfunctioned. New software has since
corrected the problem.
If the space station experiences 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 lessened and the ability to generate power is reduced, conserving the remaining battery
power is essential. The designers of the space station have determined that a 50 percent total power reduction is a critical
value not to fall below. If the reserve power levels approach 50 percent of capacity, steps must be taken to reduce the total
power draw of the space station. That means the astronauts would cut how much power some systems are consuming as a way to save
overall 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 solar arrays return to normal operation. For example, they can dim the
lights, shut down any device that’s not critical, and they can evacuate any module, which then eliminates the need to generate
light, heating, cooling, and breathable oxygen there
There are procedures governing the amount of reduction each system can tolerate. The power to conduct experiments and to run
anything not critical to support life and 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 on board the station.
Check for Understanding
Answer the following questions to see how much you know about emergency procedures on the space station.
- Name two ways solar storms can damage the space station.
The electromagnetic energy causes the solar arrays to produce less power. The storm affects the way the computers
and wires on board the station work. The electromagnetic energy can penetrate the circuitry of the computer microchips
and cause them to “flip their bits.” The memory of the chip is reversed, and the computer program will not work correctly.
- What has been done to protect the space station from dangerous solar energy levels?
Several types of shielding materials are used to help protect the station and the astronauts inside. Multiple computers
control nearly every device on the station in case one fails. Engineers have calculated exactly how much power is needed
to safely run the station in emergency conditions, and astronauts reduce the power needed or completely shut off systems
that are not essential in order to maintain power to essential systems.
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