What are tradeoffs between different kinds of power sources for spacecraft?
Every power source available for a satellite or other spacecraft has different
strengths and weaknesses. It is often through combining these different power
sources that we find truly successful power sources.
- Batteries are a reliable, consistent, and well-understood technology. Unfortunately,
power demands for satellites tend to be so high that a battery that would
be strong enough to power a satellite for the length of a mission would be
larger than the satellite itself. Thus, batteries tend to be used as temporary
storage points for power from another source.
- Solar panels, especially the modern ones, provide abundant power for nearly
all a satellite's needs and are safe and clean to launch. The downsides are:
- Solar panels are large and fragile constructions that are vulnerable
to damage from external factors (solar flares or meteorites to name two)
or even just mechanical failures.
- They are rather expensive to build and put into space.
- They need to always be pointed at the Sun, which means they aren't
useful when blocked by planets or other objects .
- They become significantly less useful the farther the satellite gets
from the Sun, which generally means solar-powered missions can't travel
much further than the orbit of Mars.
- Radioisotope thermoelectric generators are also reliable and consistent.
They tend to be very expensive to build, and public opposition to their use
is strong because people fear they might leak radioactive materials during
a launch failure.
- Fuel cells are much like batteries only they have a longer lifespan and
can be refueled. These are already in use in the Space Shuttle, and are quite
useful in other near-Earth missions. However, for long flights they need lots
of fuel. They also run very hot (400-1000 F), and the waste heat is often
hard to manage.
What happens
to a ship when it runs out of power?
What are
batteries?
What are solar
panels?
What are radioisotope
thermoelectric generators?
What are fuel
cells?
How and why do we
control heat on a spacecraft?
What is a
meteorite?
What is a satellite?
Why do
solar panels become less useful the farther they are from the Sun?
Why
do solar arrays always need to be pointed at the Sun?
How do batteries
work?
Why
is mass important?
What
is a solar flare?
