How Do Satellites Work In Space?

Space is a difficult place to be. You can't plug in a cord in outer space, so satellites need to take a power source with them. It's hard to get satellites pointed in the right direction because there's nothing to turn them with. Satellites need to work in the freezing cold of Earth's shadow as well as in the blazing heat of the Sun's rays. They also need to be tough enough to survive collisions with tiny asteroids (space rocks)!

Most satellites use both power from the Sun and batteries to work. They catch the Sun's energy using large flat solar panels. Satellites keep these panels pointed at the Sun. They use batteries when the Sun doesn't shine on them.

Satellites can stay pointed in the right direction using small rockets called attitude thrusters. They can also use instruments called gyroscopes. Sometimes magnets on board the satellite can push against the magnetic field of Earth to aim the satellite correctly.
No air flows past satellites to cool them. To keep from getting too hot in the Sun, satellites have panels that open and close. This lets heat escape. Satellites often spin so the Sun doesn't make one side so hot that it melts.

Satellites also need to be made from strong materials in case tiny asteroids hit them. They need materials that don't become brittle in the cold and the harsh radiation of space.

Another way that satellites can be power is by a "radioisotope thermoelectric generator" (RTG). These work on turning the heat from a decaying source into electrical power. They are not commonly used for satellites that orbit, but have been used in the past for satellites that operate at a distance from the sun where solar panels no longer are practical (the size of the solar panel to get the required power is too large etc). Some of the probes sent to the moon were powered by these and the experiments that Apollo astronauts left on the moon were powered by RTG's as well. The two voyager space craft had RTG's fitted as well.

In fact the two mars rovers have a type of RTG onboard, but in this case they don't convert the heat to electricity but instead use the heat to stop the components inside the rovers get too cold overnight.