In KSP Interstellar, thermal and electric rockets run on power–but producing power with a fission reactor (at least, with the technology accessible early in the tech tree) is frustrated by the high mass of the reactor and electric generator. We can beam power via microwaves, but early experiments revealed that moderately sized orbital fission reactors were not capable of producing sufficient power. We needed more. Lots more.

Solar panels collect energy from the sun; they’re lightweight and inexhaustible, but produce very little power compared to a full-size reactor. Moreover, their power falls off with the inverse square of distance to the sun, making them less effective for outer-planetary exploration.

In February of 2014, I discovered KSP Interstellar, which adds a broad array of hypothetical technologies to Kerbal Space Program. For instance, you can attach a small nuclear reactor to a thermal nozzle, and fly a small plane for several years continuously, using only air for fuel.

Kerbal Space Program is a game that, at its best, conveys the grandeur and majesty of space exploration. I suggest you put on an appropriate soundtrack and imagine the long, slow descent to the surface of the moon, in a craft surrounded by millions of miles of vacuum. Having traveled for days, shedding propellant and stages along your journey, until finally, your final stage hovers, whispering to a halt on jets of burning breath from your ancestral homeland–

Somewhere around January of 2014, I discovered Kerbal Space Program.