Complex sentence: Jordin Kare has proposed a simpler, nearer term concept where a rocket containing liquid hydrogen and water is heated in a heat exchanger that the laser beam shines on before leaving the vehicle via a conventional nozzle.
Split into simpler sentences: Jordin Kare has proposed a simpler, nearer term concept which has a rocket containing liquid hydrogen and water. The propellant is heated in a heat exchanger that the laser beam shines on before leaving the vehicle via a conventional nozzle.