I Gravity, a satellite somewhere is shot down by a missile, and the debris from that hits other satellites causing a chain reaction of rapidly increasing amount of space debris.
The protagonists are rouglhy in the same orbit with the ISS. The cloud of debris hits the protagonists, after that hitting them again every 90 minutes.
Ignoring the fact whether such a chain reaction is plausible, and ignoring whether the orbits are at correct height and time length:
Can the cloud of debris created from destroyed satellites be on a trajectory to hit the protagonists every 90 minutes?
Shouldn't any mass of debris from destroyed objects follow roughly the same trajectory as the original object? So I would imagine that in order to hit the protagonists, the debris would have to be in the same orbit, but travelling at the opposite direction. Which also means the original objects would have been in the same orbit, travelling in opposite directon. Is this plausible - are there objects around earth travelling in opposite directions in the same orbit? Or am I missing something about the orbital mechanics (I'm not an expert in space orbital physics, as you can see)?
 - it seems that the real ISS has an orbit that goes around the earth in 90 minutes, so if there was something in the same orbit in opposite direction, they would actually meet every 45 minutes.