[tech_yogi]

Could it "scoop" matter out of the atmosphere that could be accelerated by solar or nuclear powered ion drive to use as propellant?

Alternatively, thinking about the Earth's magnetic field, what if it had a big current loop that could be activated to generate a force and change orbit.

I realize that the magnitude of these effects are probably too small to be significant, but could you in principle use them to repeatedly change orbit around earth, provided you have an abundant energy source?

[eesmith]

scoop? no.

magnetic field? yes. - https://en.wikipedia.org/wiki/Electrodynamic_tether

[m4rtink]

Unlikely it can scoop material and use it for propulsion just yet, though I have seen some articles about ion engines accelerating the rarified upper atmosphere being studied.

[_Microft]

The ESA is developing an air-breathing electric thruster which sounds what you described:

http://www.esa.int/Our_Activities/Space_Engineering_Technolo...