I would love to identify a sci-fi novel I read in the late 60s or 70s. It followed a group of young space cadets through their training in the Space Academy. The training culminated in small groups of cadets being sent through a gateway in the space station, into different worlds where they had to survive whatever conditions they met beyond the gateway, as part of their training. One such trip went wrong and the group ended up stranded in a hostile world for days, hoping to be rescued by their trainers. I can't remember much about the story or protagonists so this may be too vague, but I remember descriptions of a vast space station hall and these young cadets bringing whatever kit they hoped they might need - some brought breathing apparatus and full survival gear, but others came with very little as they believed they would not be sent into conditions where they could die without the right equipment. They hadn't bargained for the power surge or whatever it was that misdirected them as they passed through the gateway! I also remember rivalry between the cadets - I think the hero was male and quietly heading for top cadet of the year award... and I think at least one of the group died in the unknown planet before they were rescued.
Does this ring a bell with anyone? I remember the mood and tension more than the details but it was a long time ago! I have a 10-year old son who I think would love this kind of story. If anyone can help you have my thanks!