Shh don't give the plot away too soon, this is meant to be the mother of all conspiracies.

Incidentally when we discover the secret of time travel in three years time there will be a couple of attempts to send urgent message bearing teams back to the past to warn us of the impending war coming up.

Not the one we are supposed to fight over oil of course but the battle alongside the rebel alliance. We are part of a cunning plan to 'seed' millions of back-worlds with both telepathic and aggressive races to fight the empire.

1951 a look at those aliens clearly show they are human that have been reverse aged and hence the look of progeria but in this case from older humans and the affect of de-aging over a significant time frame. The agents that got back to 1998 are there from the empire to misdirect all scientific discoveries to prevent the discovery of time travel and advanced weaponry.