PropulsionWhy ion propulsion? |
No, NASA could not use ion propulsion for getting spacecraft into space. Ion propulsion is a great technology to move ships once they are in space, and it is especially good for very long journeys. But it can't get a ship into space.
The reason for this is that while the specific impulse for ion propulsion is high, it gives is low amounts of thrust. A high specific impulse means that the gases shooting out of the back of the rocket are moving at a very high speed but the low thrust means that there is not a lot of gas moving at any one time. The DS1 ion propulsion engine only produces 92 mN (milli Newtons) of thrust which is roughly equivalent to the weight of a couple drops of water. This means that the ion propulsion thruster is pushing the spacecraft forward with about as much force as gravity is pushing a couple drops of water down on your hand.
We use ion propulsion in space because it does not take a lot of fuel. On a long trip this is good, because the more fuel a space ship needs, the heavier the ship will be and the harder and more expensive it will be to put the ship into space. However, in order to get a space ship into space, the ship must overcome the Earth's gravity and the resistance of the atmosphere. Getting to the right speed for this (called escape velocity) takes a huge amount of thrust, much more than an ion propulsion can produce. Conventional propulsion systems, such as liquid and solid fuel boosters, are used to put a ship into space.
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Could ion propulsion move something on Earth?
What is the difference between an ion engine and a conventional one?
What is a propellant?
How did DS1 get into space?
How does propulsion work?
How does solar electric propulsion (ion propulsion) work?
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Is there any resistance to movement in space for DS1?
What is resistance?
Why does it take so much energy to launch DS1?
What is escape velocity?
How do we put a spacecraft into orbit?
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