I did try and work out which building it was but for some reason the constructions I had assumed were linked did not seem to unlock it.

I'll take another look tonight but I just assumed it wasn't in this version.

If it's the Trade Hub in the Special constructions when I click on it I get the attached screenshot, 'Small Repair Facility' Not currently in game coming soon ....

Sorry about that, its in the transport menu, there are 2 (out of currently 3 planned) available at the moment, the first and the last, currently named small lunar pad and large freight dock (though the small lunar pad needs to be renamed I think to better describe the building)

Had a look at the trade hub tonight and it's good, once I got the hang of it.

I've attached a couple of screenshots as I have a couple of comments.

a.  I love the transparency of the UI in the game but the text needs to be backdropped by something a little darker as it makes reading it quite difficult on the trade UI.

b.  There seems to be a bug if you click the trade hub when a trade is in progress there doesn't seem to be a way to get rid of the message.

As an aside I accidentally discovered that you could slide sections out to increase the trade quantity very quickly, perhaps you could visual que that in a tutorial of the trade hub when you first unlock it.

I don't believe there are any constructions in v0.1.9 that manufature fuel (rocket) so my trade was limited to a single journey, will there be a fuel processing construction in v.0.2.0 and if so what will it be called ?

You are correct, in 0.1.9 there are no fuel producing facilities, however the way around this is to trade fuel, when ever you make a trade get some fuel on the return journey.

as to fuel in 0.2.0, yes there will be, these are included in the new buildings to be released.

As to the trade in progress, thanks for that will look into it and fix it, looks to be a simple one.

with regards to the transparency to the UI and the readability of the text this is something that has become a large problem in 0.2.0 it is something I am in the process of fixing as at full daylight and on the shinier points on the terrain the text becomes hard to read, most menus have now switched over to a transparent background similar to that of the trade menu as I thought this looked a lot better too, this has already been done for 90% of the UI that wasn't transparent.

The tutorial has become a bit of a problem over night, it was hastily done and worked fairly well, but gave it to a friend and more or less instantly broken so I have to go through it again and fix some stuff, this gives me the opportunity to make sure that is included (cant remember if it was or not) but has meant more of a delay, still would like to get it out for the weekend but as usual the game gets the better of me 😛