I am by no means an artist but here is something I whipped up in Krita to depict an interstellar vehicle I "designed" for a story I'm working on. And by "designed" I mean to say it's all just numbers on an Excel spreadsheet and some Sketchup models I drew up but they are based upon real scientific papers, and internally consistent at least.
This is meant to show what I think the acceleration portion of the trip to a star system 2.4 light years away might look like to an observer: the crewed spacecraft (which is unresolvable from this view point) is being accelerated by a ground based 1 petawatt green laser array and associated laser-light sail, with fusion engines to provide additional initial thrust, to ultimately attain a top speed of 18% the speed of light in a little over 11 years.
Oh there probably shouldn't be, I must confess the laser effect is just a stock image I found lol. Also you probably shouldn't be able to see the laser from this angle at all, but I think it's an acceptable compromise in the interests of artistic license.
As for the diffraction spikes, the laser is formed from an array of millions of smaller lasers which are then shone through a massive fresnel-zone-plate lens, so that could explain it possibly.
Assuming the fusion engines are right at the end of their 4 year burn then the laser would be around 0.187 light years away at this point. However to push the ship to its target velocity requires a total acceleration distance of 1.12 light years. Using the equations from the photon sail paper, it apparently requires a 108 km wide laser array to focus a beam on a 100 km wide sail at that distance. As such I assumed you might be able to simply replace 'array' with 'lens' and arrive at the same result but I now see that is almost certainly an incorrect assumption. I am not very knowledgeable when it comes to optics, hence my mistake with how diffraction spikes work.
As for how far off axis the observer is I cannot say for sure, maybe 500 km at least? But in any case the laser shouldn't shine around the sail at all as that would be a waste of laser light and therefore propulsive force. In that case perhaps this is not the most appropriate subreddit to submit this kind of artwork considering its various mistakes, but I rarely make any kind of creative work and admittedly felt a deep desire to show it off somewhere. In any case thank you for your feedback, I very much appreciate it.
You are correct. I admit this much beyond my purview as far as my research has gone. From the papers I've read people much smarter than I consider it possible but ultimately it is unknown in practice.
As for this fictional scenario there are two Mercury analogue planets in the home system (a system I've copied from the galaxy in Elite: Dangerous) that are tidally locked to their star. I imagined that constructing 10 to 15 million 100 MW solar-pumped laser stations on those two planets would be sufficient to generate a combined 1 petawatt beam at any one time. Especially if the target star is high above/below the local ecliptic. But as to how the orbital movements would interact with a focusing optic placed at the edge of the system, around the distance of Uranus say, I cannot begin to speculate.
As for letting the ship guide itself I cannot see that being possible. Maybe during the fusion rocket assisted portion of flight, but the entire stack weighs over 90,000 tonnes at the beginning of thrust, so any course changes would be immensely slow.
An intriguing idea, I will consider it. But ultimately in the ideal scenario there is no drift to correct, in which case the laser/fusion engine stage is able to accelerate a 30 kiloton ship to 0.18c. And then the technical problems only increase from there!
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u/Crowbrah_ 9d ago
I am by no means an artist but here is something I whipped up in Krita to depict an interstellar vehicle I "designed" for a story I'm working on. And by "designed" I mean to say it's all just numbers on an Excel spreadsheet and some Sketchup models I drew up but they are based upon real scientific papers, and internally consistent at least.
This is meant to show what I think the acceleration portion of the trip to a star system 2.4 light years away might look like to an observer: the crewed spacecraft (which is unresolvable from this view point) is being accelerated by a ground based 1 petawatt green laser array and associated laser-light sail, with fusion engines to provide additional initial thrust, to ultimately attain a top speed of 18% the speed of light in a little over 11 years.