April 24, 2026
New Form of Light Sail
In my best Mr. Spock voice with one raised eyebrow "fascinating!"
Photon drives are an old idea that go back to the invention of lasers, certainly. But there was no practical way to do them before now.
A photon drive uses light as the propellant for a super-efficient, low thrust spacecraft drive. Light moves at, well, the speed of light which creates an equal and opposite reaction, thus moving a spacecraft (just as the plasma from a standard rocket does). But because photons are massless they produce little thrust (thrust is a coefficient of mass expelled times rate of expulsion). The thing about a photon drive is, while you get low thrust, you can keep the drive running the entire trip, turning the ship around midway to decelerate. Most spacecraft drives burn until a desired velocity is reached then shut down because otherwise you would exhaust all your propellant.
The problem with the photon drive is it still requires you carry your fuel with you.
Then there were light-sails. Light sails use a giant reflective mirror as a sail, catching light from either the sun or a ground-based laser to push it along. Light sails work; Nasa experimented with a small one not so long ago. They have to be huge, naturally, and would be gossamer thin. A light sail using a long range laser cannon could get to the Centari system in about a hundred and fifty years or so, with the cannon on continuously. It is a major commitment to build and maintain the cannon, of course. And the payload would be small - you couldn't put people on it, not without suspended animation.
This is a whole new approach to using light sails as a propulsion ststen. It uses metamaterials that can move in different directions when struck by light, rather than just move in one single direction.
The article states:
The team’s metajets are composed of metasurfaces. These are ultrathin materials etched with tiny patterns. In a similar fashion to a lens, these shapes allow scientists to control the behavior of light bouncing off the devices.
By carefully designing these structures, the scientists were able to control the transfer of momentum from light to an object. This allowed the object to move, showcasing a novel form of light propulsion.
[...]
The metajets differ from other systems in one key aspect; while other methods control objects by shaping the light, this approach builds control directly into the material itself.
According to the Texas A&M team, this allows for more flexible force generation and better scalability.
It's a LONG, LONG way from this to a working spacecraft drive.
However it is tantalizing; this is a much more efficient light sail system than what we are used to considering and could well be harnessed in future to an interstellar mission.
But I don't think an interstellar mission, even one manned by robot probes, will happen any time soon. Interstellar space has lots of debris and any light sail will wind up being chewed up by space ice, in all probability, and if speeds are high enough there will be a huge radiation problem as interstellar gas comes on as gamma radiation. And it would still take decades, meaning any manned mission would require suspended animation.
But it's still fun to see this stuff develop. While we may not go to another star with this technology we can use it here in the solar system and it would work fine! Imagine going to the outer solar system in just a year or so rather than a decade or more! We could eventually build colonies in the outer system and these kinds of ships could resupply them rather easily, unlike what it would take today.
Mankind will eventually burst out into the solar system at least at some point. We are an expansive species and if we don't expand we will decay and eventually die. And one accident, say, a big meteor, could wipe us out. The only safety we have is to settle space and to do that we need better propulsion systems than we currently possess. This is a promising one.
Posted by: Timothy Birdnow at
09:23 AM
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