Decimation [ Apocalyptic Novel ]

Long ago, The world began to change. the presidencies combined and formed one government. forcing people off the planet before total extinction. which was the Worlds last chance for survival. Plan Z as they called it. All of the popuation got together running tests physical verbal and mental tests to see who would be able to withstand space. only 200 people for each space station. then that was it. The world launched into outer space. many rockets failed but at the same time many rockets were successful leading us to where we are now. we are living in space. on a newly found planet called "xephria" is where our civilization stands. the world was destroyed by an unknown Plague. its been one hundred years and the civilization is now sending teenagers every 50 teenagers is two adults each in a squadrant. there are 5 squadrants being sent down to see if earth will be habitable again. they wil confront many obsticles along the way but what exactly will they find?