The tiny rat explorers' craft was intercepted by alien probe and taken back to the home planet of a superior race of enlightened entities. These creatures, taking pity on the low intellect of the rodent astronauts decided to increase Washington & Jefferson's awareness.
After a series of mind & body altering operations the two rats became super beings. They then grabbed as much alien technology as they could, hot wired a flying saucer and headed back to Earth...