This is an image which simultaneously:
(i) depicts the surreal idea of a longboat making it to the Moon (playing on the badass reputation the Vikings have),
(ii) references the fact that the Vikings beat every other European to colonising the Americas,
(iii) and references the Viking landers (admittedly a Mars mission).
It didn't make me fall off my chair, but I smiled. It's more than the captioned wolf a couple of pages back did. Humour is subjective. Deal with it.