A proposed development program for the heat exchanger thruster and a parallel program for other key elements of a laser launch system are described. The HX thruster will be tested with different working fluids (hydrogen, helium, nitrogen, water) and power sources, and at scales from a few kW up to megawatts. Subscale launch vehicles can be tested with a variety of existing lasers, including LHMEL II and MIRACL. Laser and system development is simplified by designing around a “beam module” containing a modest‐power laser and beam director, which can be replicated to produce any desired total power. © 2004 American Institute of Physics