While they don't prevent the aliens from attacking the factory, they do prevent the aliens from making new nests closer to my factory. Since the outposts produce no pollution, the aliens mostly ignore them, preferring to walk in between them on the way to my factory. The long walk spreads out the aliens, significantly reducing their ability to damage my walls and turrets.
Here is the world map - the blue squares in the wilderness are the radar outposts:

Here is a screenshot of the radar outpost and blueprints:

Here is the mighty wall the surrounds my factory:

For anyone wondering about the solar panel to capacitor ratio: These structures produce no pollution, so the aliens ignore them for days at a time. When an attack does happen, it's usually a very large crowd of monsters that is on its way to the factory. The blueprint that I am using has not run out of power in over 20 hours, and they take only tiny amounts of damage because spitters tend to attack them only after they've been shot by the turrets.