According to NASA the Space Shuttle required 12 GW to get it off the launch pad. So if a hypothetical rocket at the Second Lagrange Point (where the JWT is heading for right now) was producing the same amount of watts, all other things being equal, how far away in space could this output be detected? For example, could the rocket's exhaust be detected here on Earth, whether visibly or by other means? Someone (not here at Physics Forum) believes it would be visible as a 14th magnitude starlike object, but I don't have the maths to verify this claim, unfortunately. (This is for a short semi-SF story, which has stalled because of this quandary).