Remember the guy who said personal computers had no use? Didn't they laugh at Fulton? Einstein had skeptics.
There's this whole realm of literature called Science Fiction, and I'm quite fond of it.
Have you thought about this? It would take thousands of years to slow any planet's rotation down.. See, planets are really really big, newton tells us that really really big things do not like to stop moving. And unless you have rockets the size of the moon and bigger then i can say that there is very little chance we could do anything, at all.
Instead, why don't you go outside and plant trees? Thats a lot better way to save our planet.