Amadeo Astronauta (1963)

Amadeo astronauta. written and illustrated by Juan Ferrándiz. Barcelona : Edigraf. 16 p.  ; 25 cm. 1963

I think it was first published in 1958 by Vilcar. So this is probably the 3rd edition.

A Spanish children's book from Madrid.  It seems to have been reprinted several times.  While fictional, the "astrofuturistic" or "retrofuturism" painted illustrations are something to see. It is the same old story of an Uncle who builds a rocket.

For the full text in Spanish see here: http://electrogermen.blogspot.com/2010/12/amadeo-astronauta.html

"Everyone talks about interplanetary travel, but I still have not told anyone the fantastic adventure that I just lived. You will be the first to know it: My uncle, a scientist in the use of atomic energy, built in secret, an aircraft for the purpose of visiting Mars. I insisted on accompanying him, convinced him to prepare our trip and on schedule, we went to the shed where he hid his strange sidereal device.

Sitting in the cockpit, each with spacesuits, my uncle and I at the power controls. We connect the drive and our ship shot toward the starry sky like a giant rocket verbena. Soon behind our planet was getting smaller to resemble an insignificant star. For how many months we sailed out? Given the vastness of the universe we lost track of time."

I tried to use Google Translate to get the text on this first page (but didn't have the patience to do them all).

But the story seems pretty clear from the illustrations.

 They have been watching us and are worried about our atomic tests.

 We are the only planet not part of our Solar System's "Congress"

You can not help but love the modernist architecture of their homes.