Chinese astronauts make rocket fuel and oxygen in space

This won't enable perpetual space travel in case anyone thought so.

Rockets need to eject particles to generate force. And to eject 1 kg of fuel, its photo synthesis system has to lose 1 km of mass in one way or another.

The solution is to find a way to generate thrust without rocket fuel ejection.

Can we "swim" through space? Collect particles from space, add energy, expell them backwards to generate a net thrust.

no particles needed, we already have ion drive, just need electricity

Ions are atoms ..... tiny particles

There's a huge density difference if you aren't close to a planet or star.

Solar sails are probably more practical.

That's called a Bussard ramjet: collect hydrogen and fuse it for power to energise the collection mechanism and thrust to overcome the drag. I think the current consensus is that the interstellar medium round these parts is too thin to make it work in deep space.

Just out of curiosity, what do you think an ion is?

Yep: https://en.wikipedia.org/wiki/Bussard_ramjet

Gather interstellar hydrogen, use it to run a fusion engine for propulsion and power. :)

Quite big tiny particles in this application: Xenon is a fairly hefty atomic number of 54 - exactly double iron.

And you need quite a bit of it: even fairly small spacecraft like probes can have nearly a tonne of the stuff. Which, considering there's only 30-40ish tonnes extracted per year at a cost of about 1.5ish dollars per gram is quite a bit!

Maybe we could travel without bodies. Ala Lovecraftian astral travel or whatever. I mean you couldn't ship matter like that but for everything else it might work just fine.

Also: https://memory-alpha.fandom.com/wiki/Bussard_collector

Star Trek assumed that all warp class vehicles would require them for operation and in-situ fuel replenishment.

Ions are small enough that you can bring enough for a whole trip pretty easily. Yes they're still consumable, but you need a tiny fraction of the reaction mass you need with a conventional rocket.

And if it would be dense enough it would work as a brake instead.

Ion drives ionize particles like xenon and expel them; they're much more fuel/weight efficient than burning fuel but they still use fuel, unfortunately.

There's been a number of pure electric propulsion proposals or prototypes, but they've all turned out to be a hoax; the latest one I recall was the EmDrive [0], where any paper claiming it produced positive thrust was debunked with the measurements having been influenced by outside forces.

The TL;DR is that reactionless drives are not possible due to Newton's third law. This page / this website is always a great resource for things like this, it's in the context of writing science fiction but it has tons of research: [1]

[0] https://en.wikipedia.org/wiki/EmDrive

[1] https://www.projectrho.com/public_html/rocket/reactionlessdr...

Astral projection isn't Lovecraftian per se (fhtagn), but it's an interesting thing to ponder from a hypothetical / fictional perspective.

At best we'll be able to send out probes. Maybe, but this still feels science fiction too, we can harness quantum entanglement for long distance instant communication.

In his books, one way of travelling was to switch souls with a creature on another planet. Apparently it worked very well. Though managing a new set of limbs and senses could be difficult.