@Ru - Re: Is this a joke?
Nuke wrote : "I do not know much about the solar sail effect, but"
Ru responded :- "So what you're saying is, you don't know what you're talking about but you're willing to rubbish work"
Quite a flame that. Seeing that almost everyone here is poking fun at the idea (painting logos etc), I just wonder why you got as far down as my comment before you came out. Especially as I was actually taking it more seriously than most and discussing the science.
I was up front with the fact that I do not know the solar sail effect. The guts of my comment refers to the paintball momentum idea. OK, lets's get more technical. I am pointing out that the momentum imparted by placing a thin later of paint on this thing is so tiny in proportion to the asteroid's momentum that it would have to be such a long time ahead of earth impact that the prediction of its future path would be unreliable. It is TFA itself that mentions the paint momentum effect as being, though less, of some significance compared with the solar sail effect. I am saying that if - IF - that is true, say within two orders of magnitude, then the solar sail idea is also impractical.
As for saying that I "know practically nothing about astrophysics and orbital mechanics", be careful what you claim about other's knowledge here. This is a techies' website after all. I don't know if you know these subjects or not yourself, but what is certain is that you know almost nothing about me. I think you might be surprised.