[mattbeckman]

You should ask SpaceX if you can print their retro space tourism posters from last year as well. You know... where these NASA artists probably got the idea from :)

http://gizmodo.com/spacex-just-dropped-these-amazing-retro-m...

[mikeash]

As that article mentions, JPL's exoplanet tourism posters preceded SpaceX's posters:

http://planetquest.jpl.nasa.gov/exoplanet_travel_bureau

In any case, no need to ask SpaceX, the posters were released into the public domain.