From Ken Ham:
And I do believe there can’t be other intelligent beings in outer space because of the meaning of the gospel. You see, the Bible makes it clear that Adam’s sin affected the whole universe. This means that any aliens would also be affected by Adam’s sin, but because they are not Adam’s descendants, they can’t have salvation. One day, the whole universe will be judged by fire, and there will be a new heavens and earth. God’s Son stepped into history to be Jesus Christ, the “Godman,” to be our relative, and to be the perfect sacrifice for sin—the Savior of mankind.
Jesus did not become the “GodKlingon” or the “GodMartian”! Only descendants of Adam can be saved. God’s Son remains the “Godman” as our Savior. In fact, the Bible makes it clear that we see the Father through the Son (and we see the Son through His Word). To suggest that aliens could respond to the gospel is just totally wrong.