Apart from a rare few of their comedies I am normally not very impressed with Nickelodeon productions. Too 'happy, colorful, perfect world stuff': children series lack some grit nowadays.
Whit that mindset The Astronauts really surprised me: the kids are not all perfect, their relationships with each other and their parents are strained. The people on the ground have no better idea what to do then they have. The AI genius is a loose cannon and as much a danger as a help.
There is real danger, real bravery. And it is not some 2 day trip but a serious deep space mission. Some very good visuals as well: the launch sequence was awesome.
On the flip side: finding a scenario that gets kids launched into space will always a bit convoluted / tricky, but I think the script writers did as well as could be expected.
Sammy reminds me a lot of 'April' in the book series of Mackey Chandler.
All-in-all I thoroughly enjoyed it and will be watching it again. I hope it gets a second series as the story is far from finished.