THE NEWEST SPACE IDEA: LASERS, SOLAR SAILS, AND COSMIC WARSAugust 21, 2018
This article was sent to me by Mr. P.G., and it's one of those thought-provoking things that sent my high octane speculation into high gear. The article is by artsophysicist Ethan Siegel, and it's well worth pondering, for reasons I'll get to in a moment:
What first caught my eye about this article was the technology that Mr. Siegel focuses on, a technology somewhere between those chemical rockets we grew up with, and the DARPA/NASA 100 year goal to have the USA be "warp capable":
Here on Earth, our dreams of interstellar travel have traditionally fallen into two categories:
- We go slowly, with rocket-propulsion, on a journey taking many human lifetimes.
- We go quickly, assuming we make tremendous scientific advances to travel at relativistic (near-light) speeds.
Either we go as the Voyager spacecrafts go, taking many thousands of years to travel even a single light year, or we develop some new technology capable of accelerating a spacecraft to much, much higher speeds. The first option seems unacceptable; the second seems unrealistic.
But something happened during the 2010s that has the potential to change the game. We've actually gone and made a huge technological advance that could impart a large amount of energy to a spacecraft over a reasonably long amount of time, allowing us to (in principle) accelerate it to tremendous speeds.
The big advance? In the science of laser physics. Lasers, now, are both more powerful and more collimated than they've ever been, and that means that if we put an enormous array of these high-powered lasers in space, where they don't have to fight atmospheric dispersion, they could shine on a single target for a long time, imparting energy and momentum to it until it reached more than 10% the speed of light.
In 2015, a team of scientists wrote a white paper on how an advanced laser array could combine with the solar sail concept to create a "laser sail"-based spacecraft. In theory, we could use current technology and extraordinarily low-mass spaceships (i.e., "starchips") to reach the nearest stars in a single human lifetime.
The idea is simple: shoot this high-powered laser array at a highly reflective target, attach a very small and low-mass micro-satellite to the sail, and accelerate it to the maximum speed possible. The ideas of solar sails are old, and have been around since the time of Kepler. But to use a laser sail would be a real revolution.
As Mr. Siegel goes on to mention, advances in new technologies are fast bringing this method of interplanetary travel closer to reality, and if a means can be found to protect the craft itself from becoming irreparably damaged by particles in space - he mentions the long term effects as turning the craft into "Swiss cheese" - it becomes even more feasible.
There's a problem though, at least according to Siegel: how does one slow the ship down, much less steer it accurately:
But there are three huge problems with this plan, and combined, they could be tantamount to a declaration of interstellar war.
The first problem is that interstellar space is full of particles, most of which move relatively slowly (at a few hundred km/s) through the galaxy. When they strike this spacecraft, they'll blow holes into it, rendering it into cosmic swiss-cheese in short order.
The second is that there's no reasonable deceleration mechanism. When these spacecrafts arrive at their destination, they'll still be moving at roughly the speeds they took off at. There's no stopping to take data or a gentle orbital insertion. They move at the speeds they move at.
And the third is that aiming to the level-of-precision needed to pass close to (but not collide with) a target planet is virtually impossible. The "cone of uncertainty" for any trajectory will include the planet we're aiming for.
The last possibility, he maintains, could mean that our "laser-sail" probes could actually impact an inhabited planet, with the force of the explosion of the Chelyabinsk meteor (which he specifically mentions in the article), and that, as noted above, could be tantamount to a declaration of war.
Which brings me to my daily dose of high octane speculation. The problem of steering and deceleration to my mind is rather simply solved, if I am understanding the concept of the "laser sail" correctly, and that is, simply have the lasers mounted in such a fashion that they can rotate, and equip the craft with a variety of sails to control direction and vector the craft accordingly, including a sail on the opposite side to decelerate the craft as one approaches the destination. I would think such a simple expedient should be rather obvious, which makes me wonder what the real point is here.
And the real point, I suspect, is not that these technologies are coming closer and closer to reality, but rather, that serious thought is being given to the subject of how not to cause an interplanetary war. After all, there could be many causas belli, besides inadvertently crashing on another inhabited planet. Merely entering into a "claimed planetary space" could do the trick by crossing some "border" of which we're unaware. In fact, I wrestled with this possibility in my talks at the 2015 Secret Space Program conference in Bastrop, Texas, by pointing out there are ancient traditions here on Earth of "quarantine zones" around the planet, a residue, I speculated, of some possible ancient "cosmic Versailles" treaty. I even offered the idea that such processes of reasoning as Mr. Siegel is advancing may have been the basis for why unmanned interplanetary probes launched from this planet carried plaques or other notices to the effect that "we come in peace."
And then there is the disturbing implication that Mr. Siegel mentions: an impact, much like the Chelyabinsk Meteor incident. Which makes me wonder - since we're talking high octane speculation - if this is not a backhanded admission that there may have been more behind that incident than meets the eye, as I speculated at the time. Was it a "message"? And if so, who really sent it?
In any case, I suspect that the mere fact that such ideas are being entertained and considered in a major publication like Forbes magazine may be an indicator that the slow trickle of information to prepare us for "something" is continuing...
... the "something" in this case being, new space propulsion technologies, and the very real possibility of interplanetary conflict.
See you on the flip side...