6 Aug
2014
6 Aug
'14
5:53 a.m.
It doesn't violate any laws of physics if you are expending power from photovoltaics to propel your spacecraft.
For example, you could push against the Earth's magnetic field to get a satellite into a higher orbit.
This article seems to confirm this model, although they don't know what they are pushing against: http://www.wired.co.uk/news/archive/2014-07/31/nasa-validates-impossible-spa...
I agree that this is probably nonsense, but maybe it isn't.