Preparing interstellar travel with ultrafast beam-powered lightsails

André Füzfa

University of Namur

Light sails propelled by some radiation beam emitted from a remote power source, aka directed energy propulsion, might be considered as the most promising candidate to send probes at relativistic cruise velocities through the Solar system and beyond. We first briefly present how one can model such accelerated relativistic flight using beam-powered propulsion with general relativity. We then give key features of relativistic navigation: the Ackeret-Tsiolkovsky equation, the rocket rest mass variation and the mission energy cost, the time dilation aboard the probe, the Doppler frequency shifts and light aberration effects due to accelerations at velocities close to the speed of light. Finally, we apply these results to describe a possible demonstrator of relativistic spaceflight in the Solar system. Such a pioneering mission would allow to develop beam-powered propulsion, acquire experience in navigation during accelerated relativistic spaceflights and pave the way to future interstellar missions.