Not directly related, but an easier question: Do we currently have the technology to launch projectiles out of Earth's atmosphere into a path such that, in a year's time or so, the planet smashes into them from the other direction and sustains significant damage?
(Ignoring questions of targeting specific points, just the question of whether it's possible to arrange that without the projectiles falling into the sun or just following us eternally without being struck or getting caught in our gravity well too soon... hmm, if we could somehow put it into an opposite orbit then it could hit us very strongly, but in terms of energy... hmmm. Ah, and in the first place there's the issue that even that probably wouldn't hit with energy comparable to that of a meteor, though I am not an astrophysicist. In any case, definitely not something to do, but (as noted) morbidly fascinating if it turned out to be fairly easy to pull off. Just the mental image of all the 'AUGH' faces... again, not something one would actually want to do. )
You'd probably have to use a more powerful kind of rocket than any that currently exists, like a nuclear rocket, to launch enough mass into space for it to cause "significant damage" upon reentry.
Any kinetic energy an object has, it has to get first. If you compare the size of satellites with their respective rocket it looks difficult to make an object of any reasonable mass get any significant speed. You can trick a bit with swing by maneuvers, but as far as I understand no man made object makes any more than a little sound at the atmosphere while entering. You could however poison the planet with a nice substance.
On the other hand it might be possible to use a man made satellite to deflect a bigger object so that it crashes into earth. But please do not try this on your home.
http://neo.jpl.nasa.gov/risk/2012da14.html
http://rt.com/news/paint-asteroid-earth-nasa-767/
Seems like a good opportunity to bring up existential risks. And A friendly reminder that NASA is in fact pretty damned important.
Thoughts?