Do you have a non-paywalled link, for posterity? I use sci-hub, but paywalls are a disgrace to science.
Also, do you have a nice reference for the bussard ramjet/ramscoop deceleration?
Obvious advantage: A priori you don’t need nuclear fusion at all. You use a big em-field for cross-section and use, ultimately, drag against the interstellar medium for both deceleration and energy generation. No deceleration needed in (thinner) intergalactic medium. Entropy gain should be large enough to run mighty heat-pumps (for maintaining high field superconductors and radiating excess heat). No need to carry fuel or manage fusion; your kinetic energy at relativistic speeds has almost as much energy as antimatter. Antimatter sucks because production, containment, and difficulty of not frying yourself with the resulting radiation (light probe cannot shield against gamma), and probably a couple more reasons.
Disadvantage: not obvious whether this works. I would appreciate an actual engineer doing the computation. (I am just a mathematician, and have not seen a study of this deceleration design because I suck at searching the literature)
Probably at least three problems:
(1) How much impulse at what speeds? Determined by cross-section of collecting EM-field over required mass of collector.
(2) Might be good for decelerating from 0.9c to 0.05c over maybe 10k years (pulling numbers out of my ass). Would still need secondary system for the remaining deceleration, until slow enough for gravity assists. Could collect propellant over the long deceleration, but then would need to dissipate a shitload of heat; unclear whether net gain.
(3) Heat dissipation.
I agree that deceleration is the thing to care about; beat the rocket equation on deceleration by clever designs using the interstellar medium, and on acceleration by big machines.
Do you have a non-paywalled link, for posterity? I use sci-hub, but paywalls are a disgrace to science.
Also, do you have a nice reference for the bussard ramjet/ramscoop deceleration?
Obvious advantage: A priori you don’t need nuclear fusion at all. You use a big em-field for cross-section and use, ultimately, drag against the interstellar medium for both deceleration and energy generation. No deceleration needed in (thinner) intergalactic medium. Entropy gain should be large enough to run mighty heat-pumps (for maintaining high field superconductors and radiating excess heat). No need to carry fuel or manage fusion; your kinetic energy at relativistic speeds has almost as much energy as antimatter. Antimatter sucks because production, containment, and difficulty of not frying yourself with the resulting radiation (light probe cannot shield against gamma), and probably a couple more reasons.
Disadvantage: not obvious whether this works. I would appreciate an actual engineer doing the computation. (I am just a mathematician, and have not seen a study of this deceleration design because I suck at searching the literature)
Probably at least three problems:
(1) How much impulse at what speeds? Determined by cross-section of collecting EM-field over required mass of collector.
(2) Might be good for decelerating from 0.9c to 0.05c over maybe 10k years (pulling numbers out of my ass). Would still need secondary system for the remaining deceleration, until slow enough for gravity assists. Could collect propellant over the long deceleration, but then would need to dissipate a shitload of heat; unclear whether net gain.
(3) Heat dissipation.
I agree that deceleration is the thing to care about; beat the rocket equation on deceleration by clever designs using the interstellar medium, and on acceleration by big machines.
Use Google Scholar to find fulltexts like https://pdfs.semanticscholar.org/847d/8dabb12f67124868af0876c77538e4fd1c60.pdf