The Myth Busters Journey

The year is 3, 745 on the planet Earth in the solar system, 400 hundreds years after the great diaspora of earth ships leaving for the stars to colonize other worlds. More than 1, 200 years after earth finally changed things around with climate change restoring earths sustainability and entering an era of high technology and exploring it's solar system.  Earth population grew to nearly 50 billion people were great Mega cities rose up into the air to house its ever-increasing population.  This time it was not war, or climate change that threatened humanity but famine and the lack of viable land to produce earths food for such a population.  In 3, 345 nearly half the earth's population left an overpopulated planet, reached for the stars full of habitable planets.
Those left behind gradually, over the course of time found themselves either, living in those mega cities now known as wild cities of chaos where the high tech of 400 years ago no longer worked.  Tame cities were mostly rural communities that have managed to sustain themselves without that high tech.  Many returning to an era from the 21st century with basic needs to get by in each tame community with their own rules and laws with no unified government and leadership.  Whereas the Mega cities where lawless often warring between different factions within their cities.  This story isn't about the Mega cities or the Tame cities.  There was a third group, called the enclaves who were scattered over the central United states.
  They had a council of elders per enclave, and an elder of Elders council over all enclaves.  They had a uniformed code of rules and laws to govern how they would sustain themselves, first by avoiding the wild cities, second, by not enforcing their Book of Rules and Laws on the many Tame cities and rural communities.  Yet, where friends of many such communities.  Each enclave served a purpose in providing skills and trades without the use of high tech, even low tech.  Akin to century old arts and crafts communities of an earlier time.  This story is about five teen boys from one enclave who sought to prove one way or another the Myth of the Diaspora.  Did colony ships really leave earth 400 years ago?  If so, where is the proof?  Where are the great ship building facilities that built these ships?  Where are the space ports these ships launched from?  And why after 400 years no one came back to check up on earth.
Like a coin it had two sides to it.  One big what if, was the other side of that story, the unanswered myth, that keeps popping up.  Did human's leave earth voluntarily, or were they taken off earth by force?  And if so, why and by whom.  Our Myth Busters, Dingus 16, his younger brother Marvin 14, Billy 16, Harry 16, and Lenny 16, all set out on a journey of more than 3, 400 miles to find answers in a world where air-cars once flew across roadways, and man had a moon stations on earth moon, and walked on Mars, and an unlimited energy source that didn't use carbon fuels to pollute earth's atmosphere.  The best source of transportation now was horse and buggy, covered wagons, or walking.