New types of engines with names like “Field Emission Electric Propulsion” I usually expect to see in spacefaring strategy games like Sins of a Solar Empire. But they are, in fact, reality, although they won’t be helping us conquer the galaxy just yet. This particular engine is immensely controllable in the amount of thrust it provides, although its maximum is 150 micronewtons. That means it’d take seven of these engines going at full blast to lift a small apple off the ground.
Of course, they’re not planning on loading a satellite with a million of these to shoot it to Jupiter. But they will be necessary to counteract with exactitude the effects of, for example, the sun’s photons hitting the spacecraft. The forces involved are incredibly small, but after a few million miles you start seeing the effects of minor uncorrected forces like that. Thus, this tiny engine (10cm wide) that can provide the incredibly small-scale adjustments necessary to keep precision instruments like probes on course.
Actually, I kind of like the idea of a few of these things holding my coffee mug up, adjusting dynamically to prevent it from falling. I smell a patent!