A debris field like the one shown so close to a planet would have to be recently formed and in the process of falling onto the planet below it. That ongoing bombardment would render the planet uninhabitable.
It is stated that the Enterprise won't enter the Kenfori system at all yet they drop out of warp in close orbit of an Earth-like planet which places them almost at the centre of the system.
The Enterprise is in close proximity to a Klingon battle cruiser, yet Una doesn't order an increased alert status, considering the circumstances going to Yellow Alert would be warranted. Nor does she order Red Alert after the Klingons raise shields and lock weapons on the Enterprise.