Solar Power
Sunlight to Power: International Space Station Solar Arrays
Learning Objectives
Science Standards
Science as Inquiry
Physical Science
Light, heat, electricity, and magnetism
Earth and Space Science
Objects in the sky
Math Standards
Problem Solving
Communication
Reasoning
Measurement
Estimation
Discussion (intro slide)
The International Space Station will be the largest orbiting spacecraft in history. The
space agencies of the United States, Russia, Japan, Europe, and Canada are working
together to build this engineering marvel. The dimensions are staggering. Its wingspan
will be approximately 110 meters and its length 80 meters. Think about that for a
moment: its wingspan will be larger than a football field. It will weigh almost a million
pounds and orbit at an average altitude of 220 nautical miles. It will hold a crew of three
during the construction phase and up to seven when the Space Station is complete. There
have been some problems here due to the cost, right now and only three people are
aboard. A plan is being developed to ensure maximum use of the station.
Worldwide research in biology, chemistry, physics, and other sciences will be conducted
in the Space Station’s six laboratories. This will open the door to future long-duration
human exploration of the solar system, as well as provide continuous benefits to science,
industry, and medicine on Earth.
Power is generated for the International Space Station by utilizing the energy of the Sun.
The Sun’s energy will be absorbed by eight solar arrays. These eight solar arrays make
up the four large, flexible photovoltaic (photo: light; voltaic: producing electricity)
modules. Modules are made up of silicon-based photovoltaic cells, which generate small
currents of electricity when exposed to energy from the Sun. These modules will produce
approximately 240 kilowatts of power, which is enough to run 60 average-sized homes.
The power obtained from the solar arrays will be distributed in several ways. Half of
the power obtained will charge the Space Station’s batteries. The batteries are used when
the Space Station is not in sunlight. They are also used when more power is needed for
experiments and research. The other half of the power produced will go directly to the
laboratories and modules, or rooms, of the Space Station. This half of the power will also
run the life support systems, which includes the air the astronauts will breath, the food
systems, and the temperature controls, to name a few. Living and working in space is an
exciting adventure. Even the way the International Space Station will receive its
electricity is wondrous. Better yet, the same method that will be used for producing
electricity on the International Space Station is also being used in homes and businesses
all over the world.
Energy sources (slide two)
There are many types of energy sources on Earth and in the universe. These include
nuclear reactions such as Fission – like an atomic bomb or a controlled nuclear power to
heat your home; and Fusion a very clean form of nuclear power that that Sun uses.
Scientists and engineers have been trying very hard for years to do nuclear fusion
because it is a very clean and powerful form of energy. It can be done, but is still very
expensive to do.
There are also fossil fuels to burn such as coal, natural gas, and oil. These fuels have
been used for centuries and are not very clean or helpful to the environment. Scientists
are also busy trying to find ways to make these fuels more efficient and less damaging to
the environment.
Other forms of “clean energy” include wind, tidal currents, and of course solar power.
(slide three)
The way a solar cell functions is actually quite simple. A reaction between two
chemicals – Boron and Phosphorous is stimulated by sunlight, causing electricity to flow!
(slide four)
Many products today use solar power. Communications satellites that send television
signals around the world also use solar cells. From toys to lights for the backyard, a
variety of products are available that use solar cells to produce their own power. Many
people also use solar power to provide electricity for their homes. Have you ever seen a
home or a building with large black panels on the roof?
(slide five)
Well, if you have, you were probably looking at solar panels. Solar panels are certainly
the “cleanest” form of energy – meaning they don’t produce waste products like gasses.
In fact, we see solar power being used every day – by plants. Plants use sunlight to
generate power. This process is called photosynthesis. And it is not too much different
from what we are doing in space.
So you might ask why isn’t solar power used everywhere? Well, the problem here on
earth is the same one we have in space - they are not very efficient. Solar panels can only
convert a percentage -- about 20% -- of the light that hits them into power. Programs are
underway to raise that efficiency level to 35% and more. And on Earth, there are other
things like clouds that get in the way.
(slide six)
So you need huge solar panels to generate power. This usually costs a lot to make and
send up to space. Remember, it still is pretty expensive to get things up into space about ten thousand dollars a pound. And the solar arrays on the International Space
Station are huge!
Well, it still costs a lot to get to space and solar cells are not very efficient, but things are
changing. New technology is being developed making solar cells more efficient. In fact,
smaller, more efficient solar panels were recently put on the Hubble Space Telescope to
replace the older, larger ones. And many government agencies and companies are
working to develop different kinds of rockets to bring launch costs down.
With these advancements, it might be cost efficient in the future to put large solar arrays
in space to produce power for cities on earth. These solar arrays could be placed in
orbits that face the sun all the time. These orbits are called retrograde orbits. The power
collected by these solar arrays would be transferred to receiving stations on Earth by
microwave energy beams. Similar things can be done to provide power for a Moon Base.
Solar energy could easily the needs of scientists or colonists on the Moon.
Mission Team Leader’s Notes
This mission helps Galaxy Explorers learn about power conversion and the difficulties of
getting and using power in space. Emphasis should be placed on understanding that
power is going to be a requirement for life support (science, work, etc.) anywhere in the
solar system. The technology must be able to stand the hostile environment of space.
(slide seven)
Activity
The Mission Team members will construct and use a simple solar collection device to
demonstrate the generation of heat created by the light of the Sun.
Materials (for each team of two)
4 paper cups, unwaxed
White paper
Aluminum foil
Black paper
Plastic wrap
Scissors
Newspaper
Tape
Apple slices
2 thermometers
Have a Mission Team conversation about the use of electricity. List how electricity is
used in homes and at school. Make a second list of ideas about how astronauts use
electricity when they are in space. Are the lists similar? How are they different? Identify
how we get electricity on Earth. Can the astronauts on the International Space Station get
their power the same way? This activity is a demonstration using the energy from the
Sun. It does not produce electricity.
Step 1: Line the inside of two cups with black
paper and place a slice of apple in each one.
Step 2: Cover the tops of the two cups with
plastic wrap.
Step 3: Make two large cones: one with white
paper lined inside with aluminum foil, the other
with plain white paper.
Step 4: Wrap each cone around a cup with the
apple slices inside.
Step 5: Cover the bottom of each cup and cone
with another cup to hold it in place.
Step 6: Crumple newspaper around the bases
of the outside cups. This serves as an insulator.
Step 7: Aim the cookers at the Sun.
Step 8: Lower thermometers into the cones.
Record temperatures.
Step 9: Cook until the apples are done.
Note: This experiment takes an estimated 2–4 hours to complete and should be conducted on a
warm, sunny day.
Cone
Cup With
Apple Slice
Cup to Hold It
All Together
Newspaper
Activity Discussion:
1. Taste the apples from each cooker. Which one of the cookers did the better job?
2. Which cooker generated heat faster?
3. How do the cookers work like the solar arrays on the International Space Station?
4. Why did you use aluminum foil in your cooker? (to reflect and concentrate heat)
Assessment:
1. Have the Mission Team members draw a diagram of their solar cooker.
2. Write a list of instructions for making a solar cooker.
Extensions:
1. Graph the temperature changes as they occur over a period of time.
2. Design and build a model of the International Space Station solar arrays using materials that
will actually conduct heat.
3. Design and build a large-scale solar cooker.
4. Make a list of how we can conserve energy on Earth and on the International Space Station.
5. Solar cells can be found in certain toys and yard lights. These can be used in demonstrations.