E.C. Tubb 
S.T.A.R. Flight [EPUB ebook] 

The Kaltich invaders sell their Earthman serfs a rejuvenation process that cruelly prolongs life. They also promise to share their secret for instantaneous space travel desperately needed by a barbaric, over-populated Earth. But decades pass and Earth is no closer to the stars. The Kaltichs continue to strip Earth of its riches and its pride.Only the Secret Terran Armed Resistance Movement opposes the Kaltichs tyranny. And only Martin Preston S.T.A.R. agent, can possibly steal their secrets. If he fails, Earth will become a planet of billions of starving people – with no place to go except to the graves.