As child (around 1985, 10yo) I read a series of scifi books for children - in german. I am unable to recall their name so I wonder if you can help id them.
It is about a group of kids. They were recruited by the professor(?) to do missions on other planets. They are accompanied by a telepathic dog that acts as translator. The dog is actually an alien from a planet of telepathic dogs (maybe wolves).
The world is not particularly advanced and is unaware of the professor and his assistants. The parents and families of the kids don't play a role. But I think there were siblings in the group (brother and small sister if I recall correctly).
The professor works in hiding with his assistants. I don't recall any assistant ever being important. The professor has a fleet of spaceships that are described similar to star wars star destroyers - huge triangular ships, but described clean. Around earth they cloak - usually inside clouds. The children never meet anybody onboard the ships, they are completely run by computers.
I recall particular story points:
- One time the children were told to go to "finis terra" for pickup. (the westernmost point of europe, located in spain). They were then going up in a transparent "lift" to a ship, hidden inside a cloud with invisible walls.
- The children were having fun ordering all their favourite sweets from the food processor on a ship.
- The planet of telepathic dogs was enslaved - or at least the race of dogs was enslaved. The telepathic dog with the kids was kind of a refugee. In one early book the children play a role in freeing the telepathic dogs. Their dog brings this up several times reminding the children to search for peaceful solutions.
Story points I am not certain are:
- There is an evil organisation hunting the professor.
- After missions they meet the professor and assistants for a celebration
- I don't think there are robots or AI around. All the ships and other machines were "programmed".