While we still dont have tractor beams in the Star Trek sense, lasers have been used in lab tests with the ability to trap and move tiny particles. As a result NASA has budgeted $100,000 to test robotic space missions that could utilize these lasers to capture stardust.
NASA was originally thinking of this idea to find a way to solve the issue of space junk above the earth.
NASA scientist Paul Stysley, a laser engineer at Goddard in Greenbelt, MD had stated that "to pull something that huge would be almost impossible - at least now".
The are several ways rovers and orbiters could utilize this technology to collecting samples from the Martian atmosphere or deep space probes for gathering passing particles.
For a planets atmosphere they would use an "optical tweezer" method. Two laser beams that overlap while moving in opposite directions create a ring-like shape trapping particles. By increasing or decreasing the strength of either beam one could heat the air around the trapped particle and move it along.
In the vacuum of space they would use optical solenoid beams capable of trapping particles then pulling them back along the length of the beam.
The other technique has yet to be done in the lab. It would use a "Bessel beam" that creates rings of light around a dot when shined on a wall. In theory this scattering of light would create magnetic and electric fields in the path of a particle that would pull it backward against the beams own movement.
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