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Cosmologist
2012-Sep-21, 12:45 PM
The most powerful engine in the solar system is Sol. How can that fusion reactor be tapped for star voyages?

ritwik
2012-Sep-21, 01:19 PM
soalr powered mini satellites
17545

JustAFriend
2012-Sep-21, 11:50 PM
Fly into it and grab some plamsa. Of course you'd be burnt to your component molecules....

Cougar
2012-Sep-22, 12:30 AM
The most powerful engine in the solar system is Sol. How can that fusion reactor be tapped for star voyages?

...sounds weird with that word "engine" in there. We can draw mechanical work from our engines here on Earth, but to date, we can only make use of the Sun's rays. The only fusion going on is deep within the Sun. The energy capability of the rays drops off exponentially with distance... Overcome these obstacles and you're on your way!

Solfe
2012-Sep-22, 03:22 AM
Doesn't Ring World "fly" its star by bobbing up and down around it? I think Niven even called it an "engine".

Simplistically, "engine" sounds perfect; the ring is a piston moving up and down and the star is the engine block.

Noclevername
2012-Sep-22, 11:18 AM
Doesn't Ring World "fly" its star by bobbing up and down around it? I think Niven even called it an "engine".


In The Ringworld Engineers it's proposed that since the meteor defense of the Ringworld is a massive solar flare converted into a gas laser, it can be used as a photon drive, pushing the sun and dragging the Ring along with it gravitationally. It did so by manipulating the star's magnetic field to create and aim the flare (the ringworld has a grid of superconductor built into it) and then doing some technomagic to make the flare lase in ultraviolet. But I don't recall any bobbing being discussed.

antoniseb
2012-Sep-22, 12:25 PM
The most powerful engine in the solar system is Sol. How can that fusion reactor be tapped for star voyages?
It is inconvenient to actually bring the star along, so what I imagine are two categories of answer:
1. Collect the star's energy (Dyson-sphere style) and put it into a storable form ... such as anti-matter.
2. Collect the star's energy and beam it in a collectible form... such as photons to a solar sail.

In Stargate Universe, the writers imagined that the ship would somehow recharge itself by diving into the upper layers of stars and collecting *something*. Was it Hydrogen? was it magical energy? I didn't really get it, but they could travel much faster than light, so there was a lot not to get. I think it was mainly to make dramatic video.

Noclevername
2012-Sep-22, 12:34 PM
I remember reading an old Omni article in the late 70s/early 80s that proposed an extremely speculative megascale project to both draw fuel from the Sun, and to lengthen the Sun's lifespan. First you had to dismantle Mercury and use its iron core to build magnetic coils girdling the Sun's equator. These would be used to alter the Sun's magnetic field so that large masses of hydrogen would be drawn from the poles and presumably held together with more magnetic fields. This would not only provide all the fusion fuel ever needed, it could, if carried out over a long enough timescale, reduce the Sun to a long-lived red dwarf (I think the release of pressure would more likely cause premature expansion, but that's just me.)

Omni was full of articles like that back in the day.

publiusr
2012-Sep-22, 08:13 PM
I miss Omni. David Egge's painting of the Dyson Megasphere especially. That might have been in Science 84' now that I think about it.

eburacum45
2012-Sep-23, 12:26 AM
I remember reading an old Omni article in the late 70s/early 80s that proposed an extremely speculative megascale project to both draw fuel from the Sun, and to lengthen the Sun's lifespan. First you had to dismantle Mercury and use its iron core to build magnetic coils girdling the Sun's equator. These would be used to alter the Sun's magnetic field so that large masses of hydrogen would be drawn from the poles and presumably held together with more magnetic fields. This would not only provide all the fusion fuel ever needed, it could, if carried out over a long enough timescale, reduce the Sun to a long-lived red dwarf

Here's an image I've made of a star being starlifted in this way
http://www.orionsarm.com/eg-article/4f55e7a94da54

Noclevername
2012-Sep-23, 12:46 AM
Here's an image I've made of a star being starlifted in this way
http://www.orionsarm.com/eg-article/4f55e7a94da54

Neat! I had forgotten what the process was called, thanks for the reminder.

Van Rijn
2012-Sep-23, 03:06 AM
1. Collect the star's energy (Dyson-sphere style) and put it into a storable form ... such as anti-matter.


Anti-matter is one of the few things that might be worth shipping from one star system to another, since even a small mass of anti-matter would be very useful. Particle accelerators can produce anti-matter, but extremely inefficiently, so a lot of input energy is required and more energy is better. One idea has been to use self-replicating machines to build huge solar collector arrays to supply the power. If that could be done in the solar system, it wouldn't be much more complicated to send the hardware off to another star to do the same thing. Vega might be a good target for that - 26 light years distant, with 40 times the luminosity of the sun, and it wouldn't have habitable planets.

cjameshuff
2012-Sep-23, 04:14 PM
The sun is an inefficient fusion engine. It'll only burn a fraction of its fuel before blowing a large fraction of the remainder into interstellar space in a red giant stage and settling down to an inert white dwarf, and it does that only in a core region a quarter the size of the entire sun, at a very low rate...far lower power output for a given volume than typical chemical combustion here on Earth, less even than warm blooded animals. It then spreads that across a rather large surface, leading to a surface temperature of only 5778 K, far lower than the 15000000 K of the core. As the efficiency of heat engines drops with the temperature difference across the heat engine, this is clearly undesirable.

So, a proposal for getting more reasonable power output out of the thing: construct a large laser array near the sun, heating near surface layers to temperatures capable of fusion at much lower pressures. This region will expand and flow outward, hopefully establishing a convection pattern that cycles fresh fuel through the high temperature fusion zone. This outflow could be used to directly produce energy via giant MHD generators, while the radiant energy could be simply reflected back into the fusion zone to increase efficiency and protect other installations in the system. Given the surface temperatures that would result, it might also be possible to support the laser and power collection systems largely with the resulting photon pressure, allowing them to operate closer to the sun.

You could then more effectively use our own sun for purposes such as antimatter production, without the inconvenience of travel to Vega.

Noclevername
2012-Sep-23, 10:17 PM
It's the most efficient positive-output fusion reactor in the Solar System. Altering its parameters would also surely vex the locals. Making it burn hotter also makes it die faster.

ADDED: What seems less convenient-- fundamentally altering the Sun, or sending a starship to another sun?

Solfe
2012-Sep-24, 12:06 AM
In The Ringworld Engineers it's proposed that since the meteor defense of the Ringworld is a massive solar flare converted into a gas laser, it can be used as a photon drive, pushing the sun and dragging the Ring along with it gravitationally. It did so by manipulating the star's magnetic field to create and aim the flare (the ringworld has a grid of superconductor built into it) and then doing some technomagic to make the flare lase in ultraviolet. But I don't recall any bobbing being discussed.

Maybe I should re-read it. I must have misunderstood or misremembered horribly.

Noclevername
2012-Sep-24, 12:11 AM
Maybe I should re-read it. I must have misunderstood or misremembered horribly.

The flare laser is first shown in Ringworld, I'm not sure if the discussion starts there or in the second book. There, I've just doubled your reading assignment! :)

Noclevername
2012-Sep-24, 01:45 AM
You may have confused it with an Alderson Disk (http://en.wikipedia.org/wiki/Alderson_disk)? The star bobs up and down inside the disk to provide day/night cycles.

eburacum45
2012-Sep-24, 03:47 AM
Anti-matter is one of the few things that might be worth shipping from one star system to another, since even a small mass of anti-matter would be very useful. Particle accelerators can produce anti-matter, but extremely inefficiently, so a lot of input energy is required and more energy is better. One idea has been to use self-replicating machines to build huge solar collector arrays to supply the power.
I've made an illustration of that process too.
http://www.orionsarm.com/eg-article/45f0c79d13c29
(you might like to read the paper I've referred to on that page as well).

Solfe
2012-Sep-24, 04:15 PM
The flare laser is first shown in Ringworld, I'm not sure if the discussion starts there or in the second book. There, I've just doubled your reading assignment! :)

Funny, I have zero recollection of the second and third book.