RE: The Sun Engine
Alvin Eriol > August 7th, 2021, 01:21 PM
Surely, if we reach the point we can move the Sun, we can deflect or destroy a threatening asteroid or comet more easily. (Okay, I'll stop calling you Shirley!)
Anyway, if the Sun were to be moved, wouldn't the asteroid or comet, which after all is in a highly elliptical orbit and still under the influence of solar gravity (not merely flying loose), move also, perhaps remaining on a collision course?
Is it possible that such action might perturb the orbits of lots of bodies that had heretofore been pretty benign, maybe setting off a new round of frequent collisions of planetoids and debris with planets and moons, including ours? The Solar System spent the 1st few 100 million yrs of its existence basically having almost all the little chunks not orbiting in the ecliptic in neat orderly rows, swept out via collisions or gravitational ejection from near solar orbit into the Oort Cloud if not interstellar space, with the biggest bodies accreting i.e. the 8 planets, esp Jupiter, and their largest moons? It seems to me the Solar System could be seriously destabilized by moving the Sun quickly. I guess that could be a plot point; by a supreme effort we save ourselves once, but doom ourselves to a higher likelihood of more unwelcome encroachments in the near future!
I don't think a Shkadov thruster would work fast enough to save Earth from an asteroid/comet strike. It was designed to let Earthlings take the Solar system on a most excellent galactic road trip, to trade in our aging Sun before it disastrously goes red giant, for a newer model! The thrust is so low compared to the Solar system's mass that noticeable changes to velocity would take hundreds of millions of years. Millenia of very tricky course correction and orbital mechanics would be required to effect the transfer of Earth to a suitable new star in a habitable orbit.
The last 3 seem similar in concept to what Larry Niven posited the Ringworld could do, given a superconductive grid capable of generating a controlled magnetic field with which to manipulate its Sun. If the Sun could be made to lase in a particular direction (a literal Death Star!) an approaching meteorite could be vaporized, with no need to go moving things around that would best be left where they are. If we did feel the need to move planets and moons around, maybe another Larry Niven concept, from A World Out of Time, would be the ticket. He posited a huge fusion engine could be deployed at a gas giant such as Neptune. It could be made to fall into the atmosphere, then fire off a hydrogen fusion puff that would pop the motor back into the upper atmosphere while giving a slight nudge to the planet. (No inhabitants, so no damage). On a time scale of millenia, it could putt-putt around the Solar System acting as a gravity tractor to move planets around to order. In that book it was used to change Earth's orbit to allow continued habitability as the Sun went red giant, and to move other bodies around as desired.