I thought that was a poor choice in the movie... they have a thousand ships and rather than actually trying to attack the invading ship, they just throw up a barrier that doesn't even harm it? This is the might of the Nova Corps?
They were ordered only to prevent the ship from reaching teh ground not to try and destroy it. As long as Ronan had the power gem he was unstoppable, all they had was Quill's plan and that was questionable at best.