one of the reactors. we just heard a problem with conditions fogged up the cameras on the bots today, but their work is critical in determining if and when humans may be able to return to the damaged parts of that plant. those robots were donated to japan by i-robot. and joining me now from boston is i-robot chief operating officer, joseph dire. joseph, glad you're with us. first, tell me, are the problems that the robots experienced today serious? >> well, you know, randi, we don't have any information as of today. we don't believe so. and we have a full set of spares and capability aboard to keep the robots working. they're very, very reliable systems, so we're confident they'll continue to perform. >> tell us about the technology that's being used, and how these robots work. >> well, the robots that we have in japan are the -- are very similar, in many cases the same. of over 4,000 robots that we have in service with u.s.