I need to know this fast, before February. I am not skilled in astronomy, as I am only in fifth grade. Please answer with a sensible answer, and with a simple "yes" or "no" at the beginning. Thank you in advance.
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1$\begingroup$ Welcome to Space Exploration.SE! Your question is currently ambiguous, please edit it and add some more details. When you write "satellites launched from space", do you mean launching a satellite into space (as in: launch from earth into an orbit), do you mean launching a satellite from another space craft that is already in an orbit, or do you mean bringing it down from an orbit back to earth? Also, please be sure to take the tour to get a hang on how this site works. $\endgroup$– DarkDustJan 5, 2019 at 9:59
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1$\begingroup$ To clarify - electricity as energy source? Or also electricity as propulsion (without propellant)? $\endgroup$– HeoppsJan 5, 2019 at 11:22
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$\begingroup$ The first satellite ever launched to space, Sputnik 1 did run on electrical energy from batteries only. No solar panels, no atitude control, no thrusters. $\endgroup$– UweJan 6, 2019 at 18:03
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2 Answers
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In a satellite, there are 3 areas where you need power:
- electronics. Obviously these can be run on electricity.
- mechanical functions (like rotating a solar panel). Electric motors cover this.
- propulsion. This is the hardest part.
Many satellites use rocket engines, which burn a fuel (i.e. a chemical process). But electric engines do exist: these are called ion engines. They use an electric field to accelerate ions to a very high speed. This is a very efficient form of propulsion, with one drawback: it can only deliver a tiny amount of thrust. This means an ion engine can't be used to launch a spacecraft from Earth. But once a spacecraft is in orbit, it can use an ion engine to get pretty much anywhere.
A famous mission that used ion engines was Dawn, which visited 2 asteroids. It was launched to Earth escape velocity using chemical rocket engines. After that it used its ion thrusters to get to Vesta, enter Vesta orbit, change orbits, leave Vesta to get to Ceres, enter Ceres orbit and change orbits around Vesta. It ran its engines for 51,000 hours, compared to the few minutes it takes most rocket engines to drain their fuel tanks.
Ion engines are also used on Earth-orbiting satellites, to make course corrections.
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$\begingroup$ There is another area where power is needed, attitude control. Reaction control wheels may be used or thrusters. $\endgroup$– UweJan 6, 2019 at 17:13
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Since you're only in fifth grade I won't get to into detail about it. As stated, your question doesn't necessarily provide enough details to answer well. However, I think I know what you're getting at.
The answer is yes, but there's a few things that make it difficult. Currently, there are some satellites that run only off of electricity once they get into their desired orbit. However, changing orbits or providing significant thrust with only electricity is slow and requires a lot of electricity. Battery technology has come a long way in the last few decades, but is still no where near what is required to launch, even from space, a satellite. So, in theory it can be done, however, it is difficult.
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$\begingroup$ No satellites use batteries as a primary energy source, they use solar panels instead (and use those to charge batteries to deal with the day/nigh cycle and peaks in power demand). $\endgroup$– HobbesJan 6, 2019 at 16:55
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$\begingroup$ The first historical satellites used batteries only, no solar panels. $\endgroup$– UweJan 6, 2019 at 17:21