I have said this in another thread about this, since it is tumbling end over end I think it is more likely that it is using some sort of gravitational assist engine that converts angular rotational momentum into orbital momentum such as this: [link to www.sciencedirect.com (secure)]

It is a much easier technologically to accomplish the acceleration seen via a gravity assist method than via a mm thick million sq. meter solar sail. It also just makes way more sense.