Q:

Is it possible to orbit a black-hole AT the event horizon?

https://en.wikipedia.org/wiki/Black_hole#Innermost_stable_circular_orbit_(ISCO)
ISCO is apparently the current theoretical limit for orbiting black holes (as sourced by wikipedia).

Original Question:
I was reading this question and many different answers eluded to the Event Horizon being the theoretical limit for orbiting a black-hole and that "bad things happen" when you dip beyond the event horizon. Is this inclusive or exclusive? Provided we were able to reach the orbital velocity required to orbit a black hole 1 mile away from the event horizon (excluding orbital drift), what would happen if we adjusted the orbit to EQUAL the event horizon, but not exceed it?
I understand the scientific possibility (with current technology) is 0%, but theoretically what would happen if we tried to orbit a black-hole AT the event horizon?

Based on the current answers, I'd like to shift the future answers to a more theoretical realm. I now understand that orbiting a black hole AT the event horizon is the SAME as being beyond it. Theoretically, how close could we approach the event horizon if we were to assume our craft is indestructible as dictated by our current understanding of physics (I realize studying a black hole up-close will likely redefine physics forever).

A:

The event horizon is a singularity, one-sided, so there's no difference between being at the event horizon and beyond it.
"Bad things happen" long before that point, though; a million miles from a black hole your orbiter would be shredded by tidal forces, and at one mile from the event horizon the orbiter would be mostly radiation. 

A:

I believe that outside the event horizon you can orbit it when traveling below the speed of light, while at the event horizon you would have to be traveling at exactly the speed of light. If you slowed down for any reason (such as colliding with particles in the accretion disk) you'd end up within the event horizon with no hope of escape.
Even traveling at exactly the speed of light and being able to maintain it indefinitely, you could only escape from the event horizon orbit by traveling faster than the speed of light, which is bad enough!
More realistically, you could orbit a black hole at a minimum distance from the singularity at which you can form a stable orbit, called the Innermost Stable Circular Orbit. In this orbit, a spacecraft could stay indefinitely without having to provide energy (Assuming no preturbations).
You could theoretically orbit a black hole within the event horizon, but you'd have to travel faster than light which isn't possible (as far as we know).

