500 pages? And you're looking for the space bar? That should not be your priority. Your priorities should be:
1. Making the margins very large without it being too obvious.
2. Finding the biggest font you can without it being obvious you're purposely wasting space.
3. Making drawings and cartoons to add to the essay, about the solar system, to create less pages needed for writing
4. Finding ways to make words and sentences longer (putting in more detail, not using contractions or acronyms, etc.)
5. Making multiple spaces between word
I hope that helps to make your report seem longer.