Altaeros just raised another $7.5 million from SoftBank to bring broadband wireless to rural areas via tethered balloons. “Launched in 2010 at MIT, Altaeros’ team anticipated from the beginning that its aerostats can be used for many commercial applications,” TechCrunch reports, citing a conversation with co-founder Adam Rein. Altaeros previously raised $7 million from SoftBank Group.