Novel way for interstellar travel

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Discussion Overview

The discussion centers around a proposed concept for interstellar travel involving a massive ring structure around the sun and a solar sail. Participants explore the feasibility, material requirements, and potential challenges of this idea, touching on theoretical, conceptual, and practical aspects of space travel.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests a ring made of materials like steel or carbon nanotubes around the sun, theorizing that a solar sail attached to it could achieve a velocity of 1/10th the speed of light due to solar energy.
  • Another participant argues that the ring would not hold together under acceleration and raises concerns about its stability and the mass required for construction.
  • A different participant clarifies that the intention is to accelerate only the solar sail, not the ring itself, and proposes the idea of magnetizing the ring to reduce friction.
  • Concerns are raised about the substantial mass of the ring, with calculations indicating it could require the equivalent mass of thousands of world trade centers.
  • One participant estimates the survival supplies needed for a 40-year journey, suggesting a significant logistical challenge for such a mission.
  • Another participant questions the practicality of constructing a ring larger than the sun and the implications of solar light pressure diminishing as the sail moves away from the sun.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the feasibility and practicality of the proposed ring and solar sail concept. The discussion remains unresolved, with no consensus reached on the viability of the idea.

Contextual Notes

Participants note limitations regarding the assumptions made about material strength, the mass of the ring, and the calculations related to acceleration and solar pressure. There are also unresolved questions about the construction logistics of such a massive structure.

udtsith
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Suppose there was a ring of some material (steel? future carbon nano tubes?) around the sun. The ring would have a diameter of 2*10^9th meters. If a solar sail were placed attached to the ring with the reflector at a 45 degree angle) then the solar sails velocity would only be limited by the strength of the material (ability to handle the accelearation and for the ring to stay connected). Still, I calculate that even with the centrifugal force of 10^6 (the same acceleration experienced by a bullet) this would net a velocity of 1/10th the speed of light. So it could take about 40 years to reach the nearest star. The benefit of this means of gaining velocity is that all your energy would be provided by the sun free of charge...it would just take time for the solar sail to reach that speed. The total circumference of the ring would be equivalent to 25X the circumference of the earth...and you wouldn't need it to do anything more than hold together until the sail detached. Any thoughts?
 
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It wouldn't hold together; it wouldn't hold together even if it wasn't accelerated.

Among other problems it would be unstable wrt the sun - read any review of the scientific problems with "Ringworld".

Also have you calculated how long it would take to accelerate up to .1c? What is the mass of your ring?

You should attempt some calculations and see what you get.
 
Thank you... and just to be clear, I am not looking to accelerate the ring, only the solar sail. the solar sail would accelerate around the ring. Perhaps to reduce friction the ring could be magnetized and the sail sit off the ring via magnetic repulsion. But maybe a ring attached around the moon for solar system travel would be better/more realistic.
 
Also, as you pointed out, I found the mass of the ring would be considerable if made out of steel. If 1 cubic meter of steel was needed then it would require an equivalent of 100,000 world trade centers in mass for the ring. If the ring need only be 10 cm^2 and 1meter long then it would still need 1000 world trade centers in mass.
 
You would need about 12,250 kg of oxygen, 14500 kg of water and 13250 kg of food per person for a 40 year journey. That totals about 40 metric tons of basic survival supplies per person. It going to be one big ship.
 
udtsith said:
Suppose there was a ring of some material (steel? future carbon nano tubes?) around the sun. The ring would have a diameter of 2*10^9th meters. If a solar sail were placed attached to the ring with the reflector at a 45 degree angle) then the solar sails velocity would only be limited by the strength of the material (ability to handle the accelearation and for the ring to stay connected). Still, I calculate that even with the centrifugal force of 10^6 (the same acceleration experienced by a bullet) this would net a velocity of 1/10th the speed of light. So it could take about 40 years to reach the nearest star. The benefit of this means of gaining velocity is that all your energy would be provided by the sun free of charge...it would just take time for the solar sail to reach that speed. The total circumference of the ring would be equivalent to 25X the circumference of the earth...and you wouldn't need it to do anything more than hold together until the sail detached. Any thoughts?
There are quite a few problems with this scenario, and with the OP.

One proposes to construct a ring with a diameter larger than the sun. Then attach a sail - ostensibly larger than the sun. Where would one propose to collect that amount of material in the solar system.

The "centrifugal force of 10^6" is missing units, and it's not clear how it applies to the sail, or from where such a number is derived.

Checking some numbers - http://solarsystem.nasa.gov/planets/profile.cfm?Display=Facts&Object=Earth - the Earth's equatorial circumference is about 4 E7 m, and 25x that is 1 E9 m, which is about half the diameter of the proposed ring.

How long would it take to construct such an immense structure? To what would it be tethered during contruction?

As the solar sail moves away from the sun, the solid angle subtended by the sun decreases. The pressure from the solar light falls off ~ 1/d2. Out past Jupiter, the sun looks pretty small, and that's not very far compard to the edge of the solar system.

Finally, this is not astrophysics.
 

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