The on-sale date is the publication date reported in U. S. Copyright Office filings.
Distributed to newstands in May 1963. This issue includes 10 pages of paid advertisements.
Distribution date from Joseph Marek's Marvel Comics Group history website.
The unaltered version of this cover was used on Creepy Worlds #68.
Text story with illustration.
Perhaps with an oxygen shortage the captain shouldn't be smoking a pipe.