New answers tagged design-alternative
1
No Earth satellite has the fuel to reach the moon. You would have to go haul it yourself--and you're getting either a broken satellite or one that's out of fuel. You'll do better to launch your own.
5
In the case where the spacecraft can achieve relativistic speeds and no gravity is involved, $\Delta v$ is actually $c$ times the maximal change of rapidity which can be achieved. So the maximal speed the spacecraft can accelerate to, starting from zero, is $c \tanh \frac{\Delta v}{c}$. For example, if the maximal rapidity is $22$, then the maximal speed is $...
7
@tfb is correct: this is another form of ion propulsion, or generally, electric propulsion. A good general reference for electric propulsion is Fundamentals of Electric Propulsion: Ion and Hall Thrusters from JPL's DESCANSO series.
The problem with electric propulsion using ultra-high exhaust velocities is the power required to drive the exhaust beam. If ...
5
That was a good description of a magnetic sail, which is a concept that is out there but hasn't been tested yet. It can change the direction of thrust by changing the orientation of the magnetic field. It has a theoretical advantage over solar sails in that the weight increases with the circumference of the sail rather than with the area, but I guess I ...
3
Let me put this in a different frame. First recall that magnetic fields also store magnetic energy:
$$
E_{mag} = \int_V H. B\, dV
$$
Now, from Lagrangian mechanics, note that:
$$
L = U-V = E_{mag}+E_{grav}-\frac{mV^2}{2}-\frac{\omega^TI\omega}{2}
$$
And let's forget some dissipative effects and the angular terms for now.
Recalling Euler-Lagrange's ...
Top 50 recent answers are included
