Now that's planning ahead

I haven't been visiting arXiv much lately, but here's a paper with someone doing some maths about keeping the Earth going despite the Sun heating up:

The 'Earth Rocket': a Method for Keeping the Earth in the Habitable Zone

The Sun is expected to increase its radiant output by about 10% per billion years. The rate at which the radius of the Earth's orbit would need to increase in order to keep the present value of the Sun's radiant flux at the Earth constant is calculated. The mechanical power required to achieve this is also calculated. Remarkably, this is a small fraction (2.3%) of the total solar flux currently intercepted by the Earth. Treating the Earth itself as a rocket, the thrust required to increase the orbit is found, as well as the rate of mass ejection. The Earth has sufficient mass to maintain this rate for several billion years, allowing for the possibility that the Earth could remain habitable to biological life for billions of years into the future. 

The method:  hundreds of rail guns shooting mass off the planet.   Surprisingly, according to his calculations, you could do it in sufficient quantities for a billion years and only have lost 1/16 of the Earth's mass.  We'd hardly notice!

I see that the author is from a community college.  I have no idea if his math is correct, but I like guys who think big, anyway.

And by the way, this puts me in mind of a short article that I am pretty certain appeared in Omni magazine decades ago, where someone did the back of envelope calculations on the idea of using the Moon as a replacement Sun, if you had Earth and Moon wandering the Universe unattached to a star. The figures, using lots of lights powered by (I think) fusion looked pretty good.  

I wonder if any reader remembers that article....