What does hacking these consoles do?
According to the wikia under the heading Control Towers,
Some Grineer outposts on the Plains have green communication towers with control consoles on them, which nearby Grineer can activate to call in reinforcements. Players can hack these towers to deactivate them, which will also deactivate any hostile turrets within the outpost. These towers can also occasionally be heard broadcasting Grineer propaganda from Councillor Vay Hek, as a prelude to Operation: Plague Star.