There wouldn't be much air to "scoop" in LEO, to get a good amount you'd probably want to be in the lower atmo.Xenon is pretty rare in the atmo, so since there's very little air in LEO, there's almost no Xenon up there.
Here's one major problem. If you dip your perigee into the atmosphere, the drag is going to decrease your apogee. And your next perigee is going to be back in the atmosphere again.The only way to raise your perigee out of the atmosphere is with a burn at apogee. But if you're using an ion drive, whch uses lowthrust over an extended time, you're not going to be able to manage a significant perigee boost before you're heading back down again. Your orbit is going to quickly degrade, until you end up re-entering and burning up.So, basically, the answer is "No."
...you 'burn' as you collect, so that you are at least counteracting your drag. Hall Effect, FRC, and Helicon thrusters have all shown to work on some combination of N2 and O2... you need an Isp that is at least the orbital velocity divided by all of your propulsive/collection efficiencies to make up for drag and more if you want to store...
We've looked at these air-breathing electric propulsion systems extensively. The ASPW (advanced space propulsion workshop) has featured several of these concepts, ours was a number of years ago. My view was this was tough, but maybe not impossible. As others have noted, the orbital mechanics is pretty easy as long as you 'burn' as you collect, so that you are at least counteracting your drag. Hall Effect, FRC, and Helicon thrusters have all shown to work on some combination of N2 and O2 (and maybe stored Xenon for the cathode). The basic idea as we understand it is you need an Isp that is atleast the orbital velocity divided by all of your propulsive/collection efficiencies to make up for drag and more if you want to store. At 100% efficiency and assuming your vehicle was a flow-through 'scoop' and stored nothing, you'd only need 800-ish seconds.But, with a 50% collection and pressurization efficiency, a 75% thruster mass utilization efficiency, and storing 25% of the gas each orbit you need an ISP of 2700 seconds. This assumes the entire front end of this thing is all scoop. I think the biggest concern is heat rejection and power. If your spacecraft is much bigger than the scoop/inlet (ie solar panels) the amount of thrust needed to counteract all of the drag gets a lot harder. And while the thruster puts most of its energy into the propellant, either heat or kinetic, the scoop doesn't have a natural way to loose energy.Cool stuff, I bet NIAC would want to take a look at this.-David
5 March 2018In a world-first, an ESA-led team has built and fired an electric thruster to ingest scarce air molecules from the top of the atmosphere for propellant, opening the way to satellites flying in very low orbits for years on end.ESA’s GOCE gravity-mapper flew as low as 250 km for more than five years thanks to an electric thruster that continuously compensated for air drag. However, its working life was limited by the 40 kg of xenon it carried as propellant – once that was exhausted, the mission was over. Replacing onboard propellant with atmospheric molecules would create a new class of satellites able to operate in very low orbits for long periods....