Science fiction is sometimes called the fiction of idea’s. You can explore things in science fiction that you can’t do in any other kind of fiction.
This can be intimating, to think you have to come up with ideas that are new and be able to use them well. However you don’t have to do that, nor will you be able to most of the time.
Even the Foundation Series, known for the idea of psychohistory, did not require Asimov to invent anything totally new to mankind. The idea of predicting the future has been about for as long as we have existed. What good science fiction does is find new ways to combining or changing ideas.
All you often need is a few ideas that you have put a new spin on, past that it’s a matter of plotting out details. Some of the best movies and books had no new ideas at all, just a good old idea that was done very well (Alien for example).
I will say that you should have SOMETHING new in your book, some combination of ideas not used before, an old idea done better then you have ever seen before, something. You should be able to tell someone in two sentences why your book is awesome and why it is new.
New does not mean it has to be jam packed with never thought of ideas.