Childrens science fiction series, pre 1985 ish

[TheCheekyPixie]

Hi all, hope someone can help

Around about 1987 my (Kent) primary school library had a series of science fiction books that I read over and over but haven't been able to track down since.

In the version my school had the books were smallish hardbacks with a pattern of turquoise and black semicircles on the cover. I remember the titles as being along the lines of 'Return to Venus', 'Journey to the Moon' but I've never achieved anything by googling likely combinations of those so I could be wrong.

The stories focussed around groups of characters, all male from what I recall but of different ages, who'd been sent to nearish places, the Moon, Venus, possibly Mars and included all kinds of complications where unexpected things happened or equipment broke or people were saved from suffocation at the last moment and so on.

I can't remember too much precise plot. I think I remember a scene where someone ran out of oxygen and collapsed into some alien plants which turned out to have small bubbles of oxygen in. I think I remember long bodied aliens at one point. I vaguely remember somebody getting trapped at the back of a cave and I'm pretty sure I remember a story where the whole scheme got cancelled and everybody had to go back to earth, only they'd all got used to the reduced gravity and had to go and explain that the program needed to carry on because all the people involved would be unable to come back.

I'd really like to see these again so I hope this rings some bells with someone!

Cheers, L