It’s not a plane, it goes into orbit. It’s a drone like satellite. A mini unmanned space shuttle. Likely uses liquid fuel and deplorable solar panels for energy. It’s launched up there on a rocket.

Just like a satellite, it wouldn’t need much energy once it’s in orbit. Just enough for repositioning. It has done progressively longer and longer missions. 2 years doesn’t seem illogical when you consider how long satellites last. Probably only limit to its mission time is how much times you move it around and deplete it’s fuel.