It is stated in the Vedic literature that there are many planets where the inhabitants are more advanced than the inhabitants of this earth planet. So it is not unlikely that such people may have developed space traveling methods. They occupy higher posts in the creation of the Lord and so they may be considered as demigods in the same way as the president is specially empowered by the nation, but this does not mean that such spacemen are necessarily carrying the messages of the Lord, just as the business of the state employee is not to act as the state representative but he acts in his particular job.
Letter to Madhudvisa, February 14, 1970