They have plans to try pushing it with microwaves (after primary mission is complete). But I think the goal is to see if there is any detectable "push" imparted from the microwaves, rather than to actually send the sail somewhere.

So back to ljk's question, is there in existence a laser that can be pointed in the right direction (and outdoors at all), that can have its beam spread out to cover the entire surface of the sail, that is powerful enough to detect any push? Just for experimental purposes, understand.

PS: you only have several weeks to set it up, if you have any bright (pi) ideas.