Monday, November 7, 2011

Science close to creating a tractor beam

Tractor beam is a stuff from sci-fi movies most notably Star Trek and refers to ability to trap and move objects using laser light. However according to the NASA scientist Paul Stysley „laser-based trapping isn't fanciful or beyond current technological know-how“.

Stysley and his team were awarded $100,000 to study three experimental methods that could make tractor beam a reality.

The first method includes the use of two counter-propagating beams of light. By alternately strengthening or weakening the intensity of one of the light beams - in effect heating the air around the trapped particle - researchers have shown in laboratory testing that they can move the particle along the ring's center. The downside of this technique is that it requires the presence of an atmosphere.

The second method refers to use of optical solenoid beams - those whose intensity peaks spiral around the axis of propagation. With this approach it is possible to trap and exert a force that drives particles in the opposite direction of the light-beam source meaning that the particulate matter is pulled back along the entire beam of light. Unlike the first method this one does not require atmosphere and relies solely on electromagnetic effects and could therefore operate in a space vacuum.

The third method is still theoretical and is yet to be tested in laboratory. It refers to the use of a Bessel beam. A true Bessel beam is non-diffractive which means that as it propagates, it does not diffract and spread out and looks like the ripples surrounding a pebble dropped in a pond. Scientists who support this theory believe that the laser beam could induce electric and magnetic fields in the path of an object. The spray of light scattered forward by these fields could pull the object backward, against the movement of the beam itself.

The scientists hope that tractor beams could be used one day for cleaning up orbital debris. But this is impossible with the current technological know-how. However, these three methods certainly have enough potential to be used for sample collection.