Can I apply for a U.S. Pport for my 15 year-old son even if the whereabouts of his father are unknown?

I would like to take him to Europe this summer but his previous pport expired, and it was issued to him more than fifteen years ago. Because of that, I need to apply for a new one. However, I am not legally divorced from my husband, and his whereabouts are unknown. How would I go about applying for a pport for my son without his father's consent?