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As far as I understand their speed mostly comes from gravity assists from Jupiter, so you'd have to wait for suitable orbital alignments and the basic technolog

by rlpb 2y ago

As far as I understand their speed mostly comes from gravity assists from Jupiter, so you'd have to wait for suitable orbital alignments and the basic technology for "much faster speed" doesn't exist.

dnh44 2y ago
I never actually knew that. My mental model for how this works was way off; I'll have to read more.
- baq 2y ago
  Play Kerbal Space Program (the original, not the sequel). You’ll become an orbital mechanics pro in a couple days.
skissane 2y ago
> and the basic technology for "much faster speed" doesn't exist. Various forms of nuclear propulsion have been investigated. None of them are anywhere near ready for missions, but that seems to be more due to lack of investment in their development (and environmental/legal/regulatory/geopolitical/etc concerns) than any scientific obstacle. If NASA/etc were really serious about it (as in willing to spend multiple billions a year on it), it could probably be made to work in only a few years.
- ivan_gammel 2y ago
  This probably can happen as soon as there’s some manufacturing and mining capacity beyond LEA, so that it’s safe to use nuclear technology without any environmental impact. Moon is an option here, so likely it’s 5-15 years after first Moon base is established (I‘d expect exponential growth of it).
  - skissane 2y ago
    > This probably can happen as soon as there’s some manufacturing and mining capacity beyond LEA, so that it’s safe to use nuclear technology without any environmental impact The idea pursued nowadays is you launch using chemical propulsion and then only turn on the nuclear propulsion once you reach a safe distance from Earth. This is different from the original 1950s Project Orion which proposed to use nuclear pulse propulsion (i.e. repurposing nuclear weapons for propulsion) from the surface to orbit, which would have produced enough fallout to likely kill a handful of people per launch (in the long-run through higher cancer rates). The question then is - is it safe to launch nuclear material to orbit using chemical propulsion? Yes, we can secure it in containers designed to survive catastrophic loss of the launch vehicle. But, will the general public believe it is safe, even if it actually is? Possibly not-which is a political obstacle rather than a technical one. The other issue is that nuclear propulsion systems can be too large/heavy to launch on a single chemical rocket, but you could launch them as multiple modules assembled together in orbit. I don’t think this need or should depend on off-Earth manufacturing or mining capacity. I think it is going to be a long time before the highly complex manufacturing supply chains needed to turn raw materials into cutting edge technology like nuclear space propulsion systems exists off Earth. But we should be able to manufacture them modularly on Earth, such that in space we’d be doing module assembly rather than manufacturing.
  - mr_toad 2y ago
    > Moon is an option here, so likely it’s 5-15 years after first Moon base is established (I‘d expect exponential growth of it). I think that’s probably a very optimistic timescale. If there’s heavy industry on the moon inside 50 years I’d be surprised.
    - skissane 2y ago
      I think it will be a long time before local manufacturing of high-tech goods on the Moon is cheaper than shipping it from Earth. Lunar manufacturing is likely to be limited to proof-of-concepts (demonstrating that we can manufacture X on the Moon, even if more expensively than shipping it from Earth), basic construction materials (“mooncrete”), rocket fuel (H2O=>H2+O2, maybe CH4 from carbon-bearing lunar ices). Likely small scale greenhouse agriculture too (to improve the crew diet), maybe even some aquaculture
FriedPickles 2y ago
> the basic technology for "much faster speed" doesn't exist. …but we’re very close. The next technique will be flying near the sun then deploying a solar sail for a huge speed boost. Voyager goes 3 AU/yr, solar sail boost with todays technology will enable 7-9 AU/yr. Highly recommend watching Slava Turyshev discuss his work on an SGL telescope, which employs this technique. https://www.youtube.com/live/lqzJewjZUkk?si=57VS4oqbaKEXmyOR https://www.youtube.com/live/lqzJewjZUkk?si=57VS4oqbaKEXmyOR

by rlpb 2y ago

dnh44 2y ago

I never actually knew that. My mental model for how this works was way off; I'll have to read more.

baq 2y ago
Play Kerbal Space Program (the original, not the sequel). You’ll become an orbital mechanics pro in a couple days.

skissane 2y ago

> and the basic technology for "much faster speed" doesn't exist. Various forms of nuclear propulsion have been investigated. None of them are anywhere near ready for missions, but that seems to be more due to lack of investment in their development (and environmental/legal/regulatory/geopolitical/etc concerns) than any scientific obstacle. If NASA/etc were really serious about it (as in willing to spend multiple billions a year on it), it could probably be made to work in only a few years.

ivan_gammel 2y ago
This probably can happen as soon as there’s some manufacturing and mining capacity beyond LEA, so that it’s safe to use nuclear technology without any environmental impact. Moon is an option here, so likely it’s 5-15 years after first Moon base is established (I‘d expect exponential growth of it).
- skissane 2y ago
  > This probably can happen as soon as there’s some manufacturing and mining capacity beyond LEA, so that it’s safe to use nuclear technology without any environmental impact The idea pursued nowadays is you launch using chemical propulsion and then only turn on the nuclear propulsion once you reach a safe distance from Earth. This is different from the original 1950s Project Orion which proposed to use nuclear pulse propulsion (i.e. repurposing nuclear weapons for propulsion) from the surface to orbit, which would have produced enough fallout to likely kill a handful of people per launch (in the long-run through higher cancer rates). The question then is - is it safe to launch nuclear material to orbit using chemical propulsion? Yes, we can secure it in containers designed to survive catastrophic loss of the launch vehicle. But, will the general public believe it is safe, even if it actually is? Possibly not-which is a political obstacle rather than a technical one. The other issue is that nuclear propulsion systems can be too large/heavy to launch on a single chemical rocket, but you could launch them as multiple modules assembled together in orbit. I don’t think this need or should depend on off-Earth manufacturing or mining capacity. I think it is going to be a long time before the highly complex manufacturing supply chains needed to turn raw materials into cutting edge technology like nuclear space propulsion systems exists off Earth. But we should be able to manufacture them modularly on Earth, such that in space we’d be doing module assembly rather than manufacturing.
- mr_toad 2y ago
  > Moon is an option here, so likely it’s 5-15 years after first Moon base is established (I‘d expect exponential growth of it). I think that’s probably a very optimistic timescale. If there’s heavy industry on the moon inside 50 years I’d be surprised.
  - skissane 2y ago
    I think it will be a long time before local manufacturing of high-tech goods on the Moon is cheaper than shipping it from Earth. Lunar manufacturing is likely to be limited to proof-of-concepts (demonstrating that we can manufacture X on the Moon, even if more expensively than shipping it from Earth), basic construction materials (“mooncrete”), rocket fuel (H2O=>H2+O2, maybe CH4 from carbon-bearing lunar ices). Likely small scale greenhouse agriculture too (to improve the crew diet), maybe even some aquaculture

FriedPickles 2y ago

> the basic technology for "much faster speed" doesn't exist. …but we’re very close. The next technique will be flying near the sun then deploying a solar sail for a huge speed boost. Voyager goes 3 AU/yr, solar sail boost with todays technology will enable 7-9 AU/yr. Highly recommend watching Slava Turyshev discuss his work on an SGL telescope, which employs this technique. https://www.youtube.com/live/lqzJewjZUkk?si=57VS4oqbaKEXmyOR https://www.youtube.com/live/lqzJewjZUkk?si=57VS4oqbaKEXmyOR