Thanks a lot, Buzz Killington...
Highly relativistic spaceflight would be fatal for passengers and instruments
71–75 of 75 posts
Re: Highly relativistic spaceflight would be fatal for passengers and instruments
#72Earlier quoted context omitted.
'a few rouge hydrogen atoms' It's rogue. Sorry, pet hate, can't help myself. That and people typing 'tounge' when they mean tongue.
Yes, sorry. I'm severely dyslexic. There's a limit to mechanical spelling help. I meant the particles that are more like Han Solo and less like Darth Maul.
No worries (and now I feel bad for haranguing someone with dyslexia), I guess it just winds me up because I see it a lot - it slips past the spellcheck.
Re: Highly relativistic spaceflight would be fatal for passengers and instruments
#73That's okay, there's time to work on the shielding. 0.03 c is the most that can be feasibly achieved using top-end near future technology like dusty plasma fission fragment rockets. https://en.wikipedia.org/wiki/Fission-fragment_rocket
Thermonuclear pulse propulsion (a la Project Orion) can do better than that- up to 0.1c. And that requires no unproven technology; just a lot of money and a lot of politics (and a lot of fission fuel to buy with that money; I dunno if it's more than you could actually get on the market or not, but it would definitely cost A Lot).
> requires no unproven technology
what will you make the pusher plate out of?
Re: Highly relativistic spaceflight would be fatal for passengers and instruments
#74There's also the risk of hitting small dust particles, etc. A quick back of the envelope calculation reveals that hitting a spec of dust that weighs just 1 ug (a millions of a gram) at 90% c produces ~36 mega joule. Not a huge amount of energy (about the energy of burning 1kg of coal), but still. Hitting a grain of sand (10mg) at 90% c produces ~360 giga joule (energy of a small lightning)
You are making a fundamental error by assuming classical kinetics. At .9c, your first interactions would be electronic (ionization), then nuclear and radiative. The complete and initial ionization of all the atoms of 10mg of, say carbon, would be a lot less than 360 GJ. Then you'd have different interactions depending on your hull material, magnetic shielding/Bremsstrahlung losses, etc... With some complicated magnet…
That's quite possible.
The mass would not go away, though, and since energy is preserved it would need to dissipate somehow.
If you can avoid the collision (as you suggest) by deflecting the particle and thus not change its momentum there would indeed be no (or less) energy to dissipate.
Re: Highly relativistic spaceflight would be fatal for passengers and instruments
#75You know what else is an obstacle to relativistic spaceflight? Being able to do relativistic space flight. Fun fact: people realized this a long time ago, and proposed different "shields" in front of the ship (it turns out that the most effective shape is a smoothed-out cone [of ice, say] -- see Asimov's Song of a Distant Earth).
Nitpick: The Songs of a Distant Earth is actually by Arthur C. Clarke.
Thank you! I always mix them up.