2039's Largest Piece of Space Debris

While Deep Purple sang of Space Truckin', Japan has something else in mind, which in comparison makes Space Truckin' sound like science-fact.

Mitsubishi and IHI plan a $21 billion project to build a solar-power generator in space in the next three decades. The station will microwave electrical power to earth and tests are to start as soon as 2015.

The station will have about 1.5 square miles worth of on-orbit solar panels and will generate one gigawatt, enough to run almost 300,000 average homes in Tokyo. As another reference to help you get your head around that number, you may remember Doc Brown needed 1.21 gigawatts to run the flux capacitor in Back to the Future.

One consultant says the program's costs need to be reduced to one percent of the current estimates for viability.