How do you stop if your solar sail has you going near light speed? Or does it strand you halfway between stars in the doldrums where the force on both sides of your sail equals out from two stars?
Also note that "solar sail" is a bit misleading, the (now apparently dead) Breakthrough Starshot design was a big reflector "sail" in space and very many lasers on Earth to power it, it's not actually driven by a stellar wind directly.
"...or by ejecting a reflector that is then used as a braking system (similar to thrust reversal on jets) but this only works if the payload is still within illumination range of the primary laser system"
Getting hit by some random molecule when orbiting Earth or just travelling say 30,000 kmh is one thing. Getting hit by swarms of molecules with say 0.5c can be catastrophic to the material. Now imagine wading through some space dust cloud, or even plasma cloud (ie remnant of some bygone supernova).
Star trek had shields, and for good reasons. Super strong magnetic field may divert some charged particle, but helium molecule is just a helium molecule, no extra charge to play with.
This is actually I "love" to think about:
What would it be like, to be "stranded" in the space far from any stars?
or in the "voids" where there are relatively very few stars/galaxies to begin with?
There must be things drifting there right now...
It would also be the perfect place to HIDE something :)
Note that the “naked eye” stars we see in our night sky are all big, bright stars in our immediate vicinity.
Outside of a galaxy the night sky would be black, other than some fuzzy smudges of other galaxies.
It would be a long time before any such species would figure out what galaxies are, what stars are, and their own relationship to those things.
Their study of astronomy would take a wildly different path even assuming they end up at the same conclusions!
And then what? What missions could they envisage, tens of thousands of light years away from the next nearest… anything?
One thing that is clear is that the intergalactic medium has a highly variable density. In the vicinity of a recent galactic merger or near-miss, there would be a smear of stars fading off into the distance.
Conversely, even a fairly quiet and passive galaxy like our own is expected to eject stars at a rate of one every few hundred years from the core region immediately nearby the black hole there.
Even better, (or worse): A species that evolved on a rogue planet! Without any star!! (heated by it's core or nuclear elements or space magic or whatever)
> It would be a long time before any such species would figure out what galaxies are, what stars are, and their own relationship to those things.
Humans are bad enough with our "We're unique and special!" complex, imagine theirs!! lol