Mimimum power requirements

We need to accelerate to at least 0.1 c to accomplish the mission. We can calculate the kinetic energy of the payload moving at that velocity to get a minimum energy budget for the mission. So

    Emin = 1/2 m v2 = 0.5 x 106kg ( 3 x 107 m/s )2  

This comes out to 4.5x10²⁰ joules. We'll need to accomplish this in certainly no more than half the time of the mission, so we can get a minimum power requirement

    Powermin @gt; Emin/(1/2 T) = 4.5x1020 / 1.5x109 = 300 Gigawatts.

Of course we are very unlikely to manage anything like the efficiency described here. Lots of energy is going to go into things other than the payload. We've no method for deceleration that won't need energy as well: running into the planet at full velocity is likely to be messy. But we already budgeted for that by using only half the time. A real minimum for our average power requirements is likely well about the 1 Terawatt level.