Making a planetary flyby in another star system at 0.2c? What if the 1g probe's course is slightly altered by interstellar dust or similar? Does it have its own propulsion? How is it supposed to navigate?IMO this is one of those "Moore's law will fix everything" concepts.
Quote from: Oli on 04/13/2016 07:47 amMaking a planetary flyby in another star system at 0.2c? What if the 1g probe's course is slightly altered by interstellar dust or similar? Does it have its own propulsion? How is it supposed to navigate?IMO this is one of those "Moore's law will fix everything" concepts.If a spacecraft is 4 meters wide and flies 4 light years, how much dust on average is in a column 4 meters by 4 meters by 4 light years? I can imagine even a gram of dust in that column will pulverize a spacecraft flying at 0.2c.
Regarding the probe's ability to transmit back to Earth - is it possible that the sail could also act as a radio antenna? The same sail that is catching the laser beam to push it ahead would also be able to use some of that caught laser energy to power any transmissions.Would the dimensions of the sail be large enough to make that feasible?
Did some BOTE calc for the fun. Assuming 4m diameter disc weighing one gram the required beam intensity to accelerate the craft at 60000g is 7GW/m2. Further assuming 99,9999% reflectivity on the mirror side the craft absorbs 7kW/m2. If the other side is perfect black body it can reradiate the heat at required rate if the craft can survive about 600K. Not horribly hot, but is hextuple-9 reflectivity within realm of possible idk.
let's stay serious... (burning dollar bills for fuel isn't very serious, is it?)
1. Instead of providing propulsion for a micro craft, wouldn't the laser array be a death ray weapon if the energy was reflected off a heavy mirror in orbit around the earth?2. If there is a military application then funding the laser array shouldn't be a problem.
If a spacecraft is 4 meters wide and flies 4 light years, how much dust on average is in a column 4 meters by 4 meters by 4 light years? I can imagine even a gram of dust in that column will pulverize a spacecraft flying at 0.2c.
When I expressed skepticism for this project and it's technological feasibility on a Space.com announcement feed on Facebook - jeez; you should have seen the feral responses and attacks I got! I was called all sorts of names, most of which have been deleted now. The mildest response I received was folk wondering how the great Professor Hawking could be so wrong and me - the wise and all-knowing 'Matthew Black' could be so right?! I responded "It's not about that; this kind of project and conceptual kite flight is part of how Prof. Hawking makes a living these days".I conceded that the whole concept is vaguely plausible, but that there would be considerable technical, financial and scheduling challenges to overcome. Not unlike 'Mars One' in that regard!!