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Yes, but they only work on low gravity bodies such as asteroids, as the thrust produced is quite low. They don't work in an atmosphere because the atmosphere would cause an arc between the ion generator and the ion accelerating grid, shorting them and removing the accelerating field, or melting the ion drive. Or, if the electric field between the ...

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The question has already been answered pretty well, but I think more explanation of why big antennas help would be worthwhile ... Antennas have a property called "gain" which means that they work best in one direction (or several directions, depending on the type of antenna) and less well in others -- so a transmitting antenna with high gain sends its ...

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There's a little mistake in the signs, since the potential energy is given by $U=-\dfrac{GMm}{r}$. The problem of finding the time elapsed between two points of the trajectory may be done by realizing that at any point $$\frac{1}{2}m\dot{x}^2-\dfrac{GMm}{x}=E=-\dfrac{GMm}{H},$$ where $H$ is the maximum height of the particle. Hence ...

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This selection was made in 2008, when only 7000 near Earth objects were known. This asteroid was chosen for several reasons: It's easy to get to. This is the most important concern. Most of our interplanetary missions never come back to Earth. One of the key goals of OSIRIS-REx is to return a sample of the asteroid to Earth. The vehicle has to carry the ...

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The answer is right there in your own math. You derived that the delta V that results from using the rocket as a single stage rocket is $$\Delta V_{\text{single stage}} = v_{ex}\ln\Bigl(\frac{M}{M-(m_{fa}+m_{fb})}\Bigr)$$ while the delta V from using the rocket as a two stage rocket is \Delta V_{\text{two stage}} = v_{ex} \Biggl( ...

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Put your math aside for a minute, and take a lesson from Robert H. Goddard, in one of my all-time favorite papers. Basically your rocket consists of a payload H, and the rest of the rocket consisting of fuel mass P, plus non-fuel mass (i.e. tank) K. The secret is, as you shed P through combustion, you must also shed K. Otherwise as P gets smaller and ...

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