One is an adaptation of a well-known effect called "optical tweezers" in which objects can be trapped in the focus of one or two laser beams.

BBC: Nasa examines 'tractor beams' for sample gathering

As is well known to participants in the sport of Base Jumping (a mind-bogglingly dangerous activity that involves parachuting from static objects), parachutes have problems when launched from tall buildings.

ECONOMIST: Safety