H. Beam Piper
Here is a great science fiction novel first published in 1958.
There are a whole lot of sci-fi/ space novels from around that time. What is different about this one? Well, for one, I REALLY liked it. I think this is just as good as Jules Verne and H G Wells. Yes, it is that good.
I listened to this one on audio. I downloaded it for free. You can try it out on an mp3 player and see what I mean. You can get it here: The Cosmic Computer at Librivox.com
You won't be disappointed.