“As Dawn flew 2,700 miles...”
That’s really far away! Why don’t they want to get any cloer?
Well, they are using ion drives, which are very efficient, but generate very little thrust, so they take a long time to do any maneuvers. Just lowering to that orbit is taking them almost a full month of burning those engines!
So I am guessing they are trying to save fuel, and going any lower is not worth it. Remember, they have to burn their engines to get to a lower orbit, and then they’d have to burn even more to get back to escape velocity and get away from the planet’s gravity.
That’s really far away! Why don’t they want to get any clo(s)er?
Now you know why...................