‘Tractor beams’ – invisible beams that can push and pull objects – are a staple of science fiction.
In Star Trek, the beams are used to haul spaceships across space, capture floating capsules and even snare fleeing enemies.
It’s not just science fiction writers who are interested in the idea, though.
Nasa has put aside $100,000 to research the idea of using lasers to ‘drag’ particles from vehicles such as Mars Rover to orbiting space craft.
Particles is the operative word – the real ‘tractor’ beams will be able to move particles the size of a living cell, but nothing bigger.
At that scale, though, Nasa says the technology is ‘not beyond current technological know-how.’
Nasa Principal Investigator Paul Stysley and team members Demetrios Poulios and Barry Coyle at NASA’s Goddard Space Flight Center will study three experimental methods for corralling particles and transporting them via laser light to an instrument — akin to a vacuum using suction to collect and transport dirt to a canister or bag.
Spacecraft such as Star Trek’s Enterprise use ‘tractor beams’ to push and pull objects across space – but Nasa thinks the idea may not be so far-fetched
‘Though tractor beams are a mainstay in science fiction, and Star Trek in particular, laser-based trapping isn’t fanciful or beyond current technological know-how,’ Stysley said.
The team has identified three different approaches for transporting particles, as well as single molecules, viruses, ribonucleic acid, and fully functioning cells, using the power of light.
‘The original thought was that we could use tractor beams for cleaning up orbital debris,’ Stysley said. ‘But to pull something that huge would be almost impossible — at least now. That’s when it bubbled up that perhaps we could use the same approach for sample collection.’
One experimental approach the team plans to study — the optical vortex or ‘optical tweezers’ method — involves the use of two beams of light ‘orbiting’ one another.
Goddard laser experts (from left to right) Barry Coyle, Paul Stysley, and Demetrios Poulios have won NASA funding to study advanced technologies for collecting extraterrestrial particle samples
The resulting ring-like geometry confines particles to the dark core of the overlapping beams.
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.
Another technique employs ‘optical solenoid’ beams – spiralling around the object. Testing has shown that the approach can trap and exert a force that drives particles in the opposite direction of the light-beam source.
The researchers found this technique can operate in a vacuum.
The third technique involves a ‘Bessel beam’ – a laser writh ‘rings’ of light around a central point. The beam could – in theory at least – induce magnetic fields in the path of an object, pulling it backwards against the movement of the beam.
‘We want to make sure we thoroughly understand these methods. We have hope that one of these will work for our purposes,’ Coyle said.
‘We’re at the starting gate on this. This is a new application that no one has claimed yet.’