I just started learning about space travel. I’ve heard that a spacecraft propulsion system either has high thrust + low specific impulse, or low thrust + high specific impulse.
As far as I know, high thrust means a propulsion system has high mass flow rate, achieving higher acceleration.
High specific impulse means a propulsion system can generate more thrust for given amount of propellant used, achieving higher fuel efficiency.
So if a propulsion system such as ion thruster has higher specific impulse than chemical rocket, why can’t engineers increase the output of ion thruster to increase thrust, achieving both high fuel efficiency and high acceleration to replace chemical rocket?
In: Engineering
It’s pure tech happenstance, rather than anything physics.
We have two basic techs for space propulsions:
1. Burn something and toss the burnt stuff out the back.(high thrust, low ISP)
2. Use electricity to throw something out the back.(low thrust, high ISP)
Now there’s been the idea of using a lot of nuclear explosions to move a space craft.
They did the math and found it has far more thrust than any rocket we’ve built.
And it’s going to have the specific impulse close to some of the ion thrusters we’ve built.
But we don’t use it because exploding many nukes in the atmosphere is bad for the environment, and many countries find nukes in space scary.
But from a physics standpoint, nothing is wrong.
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