<snip>Large nuclear powered Ion type propulsion will probably be the only way to travel past Mars or Ceres.
For interstellar missions, I would think you would use starship to loft a large VASIMR engine and possibly a another launch with a 100kw + class of solar panels. Have this engage it's VASIMR engines in a long arc around the sun as it powers the VASIMR engine and gains a lot of velocity. Then it would separate with an ion stage powered by your best Stirling Isotope Generator with complimentary battery packs that could charge and discharge for thrust pulses of the ion drive.Even after all of the best propulsion/power tech with gravitational assist helping out (perhaps a Jupiter gravity assist) we might get about 100Km/sec this is blazingly fast, yet woefully short of any reasonable timeline to even the nearest star.Ok, forget that, let's use Starship to build a laser-powered sail network, or wait until we have a practical fusion drive.
Two relevant tweets from Elon:https://twitter.com/elonmusk/status/1111760133132947458https://twitter.com/elonmusk/status/1111798912141017089
Quote from: 50_Caliber on 06/14/2020 01:30 amFor interstellar missions, I would think you would use starship to loft a large VASIMR engine and possibly a another launch with a 100kw + class of solar panels. Have this engage it's VASIMR engines in a long arc around the sun as it powers the VASIMR engine and gains a lot of velocity. Then it would separate with an ion stage powered by your best Stirling Isotope Generator with complimentary battery packs that could charge and discharge for thrust pulses of the ion drive.Even after all of the best propulsion/power tech with gravitational assist helping out (perhaps a Jupiter gravity assist) we might get about 100Km/sec this is blazingly fast, yet woefully short of any reasonable timeline to even the nearest star.Ok, forget that, let's use Starship to build a laser-powered sail network, or wait until we have a practical fusion drive. Isn't the whole gist of VASIMR that you can switch between high thrust/low Isp and low thrust/high Isp? Surely if you're embarking on an interstellar mission you would want to go the high Isp route only, and at that point you could design a novel engine which trades versatility for efficiency. I would imagine that an expendable Starship could, in conjunction with multiple gravity assists, kick such a vehicle on a hard enough escape trajectory that you wouldn't even need to think about gravity losses from the Sun. The ideal engine's exhaust might almost more resemble a charged particle beam than a spew of plasma, if you only really cared about specific impulse, don't you think?
Quote from: _MECO on 06/14/2020 09:36 amQuote from: 50_Caliber on 06/14/2020 01:30 amFor interstellar missions, I would think you would use starship to loft a large VASIMR engine and possibly a another launch with a 100kw + class of solar panels. Have this engage it's VASIMR engines in a long arc around the sun as it powers the VASIMR engine and gains a lot of velocity. Then it would separate with an ion stage powered by your best Stirling Isotope Generator with complimentary battery packs that could charge and discharge for thrust pulses of the ion drive.Even after all of the best propulsion/power tech with gravitational assist helping out (perhaps a Jupiter gravity assist) we might get about 100Km/sec this is blazingly fast, yet woefully short of any reasonable timeline to even the nearest star.Ok, forget that, let's use Starship to build a laser-powered sail network, or wait until we have a practical fusion drive. Isn't the whole gist of VASIMR that you can switch between high thrust/low Isp and low thrust/high Isp? Surely if you're embarking on an interstellar mission you would want to go the high Isp route only, and at that point you could design a novel engine which trades versatility for efficiency. I would imagine that an expendable Starship could, in conjunction with multiple gravity assists, kick such a vehicle on a hard enough escape trajectory that you wouldn't even need to think about gravity losses from the Sun. The ideal engine's exhaust might almost more resemble a charged particle beam than a spew of plasma, if you only really cared about specific impulse, don't you think?VASIMR is a pretty capable propulsion technology and may be enough for all of the thrust, I think it's main drawback is that it requires a lot of power which would be massive. Depending on which performance parameters you believe, the more advanced ion drives can surpass it's ISP with less thrust. I will leave that up to those more knowledgeable than me to sort out the best configuration for high speed travel. I suspect there are tradeoffs for whichever configuration you choose.
Quote from: Kazioo on 06/14/2020 12:51 pmTwo relevant tweets from Elon:https://twitter.com/elonmusk/status/1111760133132947458https://twitter.com/elonmusk/status/1111798912141017089 I think Tim needs to look up the price for those kick stages. It seems insane that they could cost more than an entire Starship, but it's going to take a while for the new reality to work it's way through the system. I just hope they don't accidentally travel back in time with that extreme maneuver.
I still believe the best option is take the guts out of a starship and replace it with an NSWR engine. Below is a refreshed article. It claims earth to jupiter in about 10 days. https://www.linkedin.com/pulse/20140724165847-39571567-nuclear-salt-water-rockets-revisited/